PHOTOCHROMIC

Complete Guide Book To Learn About
Photochromic
Technology
Table of Contents

Introduction

Photochromic is a fascinating technology that has revolutionized lens, visors, face shields and goggles manufacturing industry. Until now, not much information is available online on photochromic technology. This has proved to be a nightmare for manufacturers and OEM business who need up-to-date information on photochromic technology.

In this complete guide to photochromic technology, I will explore all the vital aspects – from basic definitions, working principle to all possible applications. This photochromic eBook is an eye-opener for students, engineers and business that intend to venture into this industry.

With practical examples and relevant sources of information, supported with scientific experiments; you should be an expert after reading this eBook.

Free Bonus : download this free photochromic e-Book to become an expert about photochromic niche.
Chapter : 1

Photochromic Definition: What is Photochromic?

1.1 Definition

Photochromic is a “compound word” made of “photo”, which means light and “chroma” meaning color.

Photochromic is a substance that undergoes reversible transformation on exposure to electromagnetic radiations. Alternatively, you may describe the process as a reversible change in color on exposure to light.

So, what exactly do I mean by this?

Normally, when you expose a photochromic material to a sufficient light intensity (UV radiation); it will tint and turn back to clear state whenever there is no activating light. Tinting is a progressive process that increases with light intensity – they are somehow directly proportional.

You can see this in the video below:

 

I am quite certain that you have seen surfaces with such kind of behavior before. May be, this may seem mysterious, but trust me, it isn’t. You will understand this better after reading about the photochromic properties or chemical elements that causes photochromism.

photochromic sheet

First, let me take you through a quick history of photochromic technology.

1.2 Background information about photochromic technology

Photochromism is a phenomenon that was discovered in the late 1880s by Markwald. Markwald called the process phototropy until the 1950s, when Yehuda Hirshberg proposed the use of the term photochromism.

Basically, the degree of photochromism is molecular dependent. That is, the nature or type of molecules on the surface will determine the sensitivity of the photochromic material.

Since then scientists have come up with a number of processes to develop photochromic materials such as:

  • Pericyclic reactions
  • Cis-trans isomerizations
  • Intramolecular hydrogen transfer
  • Intramolecular group transfers
  • Dissociation processes
  • Electron transfer (oxidation-reduction)

I know these may sound too technical, but you don’t have to worry. I will focus on what you need most in this photochromic eBook.

So, when did the idea of making photochromic lenses begin?

The first photochromic lenses were developed in the 1960. Thanks to Roger Araujo, who was working at the Corning Glass Works Inc.

Since then a number of companies have ventured in the photochromic industry. Every company investing in R&D to produce the best photochromic lenses for the dynamic market needs. Of interest are: WeeTect, which has developed its unique WeeTect Photochromic Technology (WPT) and Transitions that introduced their Variable Tint Optics.


WeeTect Photochromic Technology (Co-molding)

For a fact, this technology has a brighter future, more so in the sporting and safety industries. This has also resulted in a number of photochromic related studies (I will highlight that later).

But before that, let me review the properties, elements and compounds in photochromic lenses.

1.3 Photochromic properties and compounds

I know most people find this mysterious simply because they don’t understand the concept behind photochromic materials. Ideally, this is a chemical reaction that takes place spontaneously.

Photochromic compounds are carbon-based molecules. Depending on the type of molecules or compounds, they react differently by changing their molecular structure on exposure to ultraviolet radiation.

The molecules undergo a structural isomerization where the following may occur:

  • Photo-induced geometrical isomerization
  • Photo-induced ring-opening reactions
  • Photo-induced closure reactions

Naphthopyrans is a popular photochromic compound whose structure is altered on exposure to the UV radiations. However, their molecular structure changes reversibly. Normally, this process happens so fast that you will hardly notice. That is, the tinting process takes place within the first few minutes.

 


An image of fused-naphthopyrans;showing structural changes that occur when the molecule is subject to UV radiation

The photochromic properties (to be explained further in the next chapter) vary depending on the specific compound. It is actually for this reason that you will notice different photochromic lenses may have unique tints.

Below are four other different types of photochromic compounds and their unique chemical bonding structures:

  1. Spiropyrans and spirooxazines

One of the most popular photochromic compounds whose lifetime is affected by prolonged exposure to UV radiation. Therefore, it is important to add stabilizers, add dyes to polymer matrix or barrier to oxygen. This is the only sure way to prolong their lifespan.

 


A reversible change when Spiropyrans and spirooxazines is subjected to UV radiation
  1. Diarylethenes

Diarylethenes are popular for their thermodynamic stability and they have a crystalline powder appearance. These photochromic compounds only change color when either dispersed in a suitable matrix or dissolved a solvent.

 


Dithienylethene compound. Image source: Wikipedia
  1. Azobenzenes

Mainly used in light controlled switches due to their unique supramolecular result.

 


Azobenzene transitioning from normal color to dark and vice versa. Image source: Wikipedia
  1. Hexaarylbiimidazole

It’s colorless in its natural state and begins to tint on exposure to UV radiation.

 


Hexaarylbiimidazole structure. Image source – Royal Society of Chemistry

As you can see from above, photochromic compounds tend to have a complex molecular structure that vary slightly. This is why I highlighted earlier that every photochromic molecule, will tend to have a lightly different property.

These molecular structures tend to be complex and it requires someone with a background in chemistry.

Research institutions have been conducting experiments and studies to get the best photochromic lenses and materials. It is a continuous process, aiming to introduce even better products in the market. This is crucial for individuals and companies that wish to focus on photochromic technology.

1.4 Studies on photochromic technology

For people who wish to learn more on the chemical bonding and synthesis process, here are more useful photochromic resources that can help expound on this subject.

  • Photodissociation of hexaarylbiimidazole. 1. Triplet-state formation – From The Journal of Physical Chemistry
  • Physics and Chemistry of Photochromic Glasses by Alexander V. Dotsenko, Leonid B. Glebov.
  • Fatigue resistant properties of photochromic dithienylethenes – From Royal Society of Chemisty
  • Structural and Photoisomerization Cross Studies of Polar Photochromic Monomeric Glasses Forming Surface Relief Gratings – From Chemistry of Materials
  • The isolation and photochemistry of individual atropisomers of photochromic diarylethenes – From The University of Groningen

Otherwise, for the scope of this photochromic eBook, I will move to more practical aspects of this technology such as: how the photochromic technology works (in real life) and the various technologies adopted so far. All these will in the next chapters and it is important for businesses or companies that wish to venture in the photochromic lenses or glasses.

I think this will give you a better understanding of how the above complex chemical compounds work. More importantly, you can use them for your photochromic lenses, safety goggles and glasses.

Chapter : 2

Photochromic Technology: How it Works

Let’s now move away from the complex chemical equations that make up a safety photochromic lens. I would like to introduce you to the practical aspect of the above chemical equations.

As a photochromic lens OEM business or sales representative; I have no doubt your buyers will demand that you explain to them the working principle of photochromic technology. I will make this simple and easy to understand with appropriate images where necessary.

First, let me make this clear

These are not Transitions lenses, the right term is photochromic lenses. It is quite common to find people referring to these lenses as “transitions”. Well, this is because Transitions brand did popularize their photochromic lenses as early as in the 1990s.

For instance, WeeTect has introduced their unique and advanced photochromic lenses going with a brand name: WeeTect Photochromic Lenses (WPLs).

weetect photochromic lens

So, with proper marketing, people may begin to coin the name as WPL.

First, I want to introduce you to a simple video on photochromic lenses made by the

TheAncientScholar.

Here is another video that is also useful video by Audiopedia. This is yet another insightful video that will help you understand all the vital aspects of how photochromic lenses works:

I hope you found this useful. Can you see how the lens changes smoothly when exposed to UV radiations? Good, now you have a clue of what I am just about to talk about next.

All I want you to appreciate is that there is an overall change in structure whenever photochromic molecules are subjected to UV radiations. Subsequently, this causes the surface to turn from light colored to tint/dark.

An image showing how naphthopyrans change when exposed to UV radiations. Image source The American Society of Chemicals

NOTE: Please note this (don’t get confused):

In my list of photochromic compounds (in Chapter 1), I didn’t mention silver chloride.

Why?

This is because the modern photochromic lenses are made from plastic materials such as polycarbonates. It is for this reason that manufacturers use carbon based molecules such as naphthopyrans (discussed in chapter 1).

Of course, before the 1990s,photochromic compounds used on glasses were mainly made from silver compounds. That is, the silver compounds were basically embedded on the glass lens. These were mainly molecules of silver chloride or silver halide.

How photochromic lenses, whether with carbon or chloride compounds. Image source: Rudy Project North America

Still, you can find photochromic glasses in the market with silver compounds. However, polycarbonate lenses are apparently becoming more popular. This is due to the desirable shatterproof property of polycarbonates.

photochromic polycarbonate sheet

Here’s what to note on how photochromic works

You need to note these important points:

  • Photochromic molecules change on exposure to UV light to create a darkening effect
  • UV radiations cause these molecules to change the shapes/structure that absorbs light
  • As more UV light reaches the lens surface, it progressively darkens to block out most harmful radiations. In fact, photochromic lens cuts nearly 85% of UV radiation within the first 10 minutes.
  • Removing the UV light initiates a reversal process. The changed photochromic molecules retain their initial structure or “returns” back to the initial shape, allowing more light to pass through (transparent or light color).

In short, it is the UV radiation that activates a change in naphthopyrans or silver chloride/silver halide molecular structure. This change in structure helps to block harmful radiations, whose effects appear as a darkening effect.

Possible questions a client may ask

Quite a number of photochromic lens markers do find themselves in a difficult situation at times. Let me help you when it comes to this:

  1. Why don’t my photochromic lens darken indoors, even when I turn my fluorescent lamp on?

These lenses only respond to the UV radiations. UV radiations have smaller wavelengths, usually from (10nm to 400nm). They are shorter than visible light, though, and possess a lot of electromagnetic energy. It is this strong electromagnetic energy that initiates the change in the structure of the photochromic molecules.

 

  1. Can normal glasses (tinted) substitute photochromic lenses/glasses?

No, this is not possible. Photochromic glasses are designed to automatically change from clear to dark (tint) on exposure to UV radiations. The normal glasses/lenses are tinted to block only specific type of light. They only possess colored filters that only allow specific colors to pass through. So, when it comes to safety, photochromic lenses are better as opposed to normal or tinted lenses/glasses.

 

  1. Do polarized and photochromic lenses have the same working principle?

No, these are two different technologies. Polarized lenses, mainly behave as “slits” that allow light from only one direction. As a result, they will only allow a fraction of light to pass through the lens/glass, giving an appearance of darkened view. However, they don’t filter the UV lights in line with the polarized surface.

 

2.1 Photochromic Material

Engineers and scientists use different techniques to classify materials for specific applications. For this photochromic eBook, I will quickly review smart materials.

These are materials whose performance, properties or molecular structure can significantly be altered by one or more external stimuli. This could be stress, UV light, temperature, moisture, electric field, etc. Normally, these changes are significant and they can be measured, seen or tested.

For instance, the table below shows examples of smart materials with the corresponding external stimuli that alters their physical property or performance and the expected change.

Type of material Stimuli Measurable output
Photochromic UV radiation Change in color (the change is reversible)
Thermochromics Temperature Change in color
Thermoelectric Temperature Potential difference
Piezoelectric Deformation Potential difference
Magnetostrictive Magnetic field Deformation

For the scope of this chapter, I will focus on photochromic materials whose measurable output is a reversible color change due to exposure to UV radiation.

So, what that this tell us?

Any material that exhibits such as property is a considered a photochromic material. In short, as long as the material has compounds I had mentioned above then it qualifies to be one. That is, it may contain silver chloride, solver helide, Naphthopyrans, Diarylethenes, Azobenzenes, Hexaarylbiimidazole, Spiropyrans and spirooxazines.

Before you purchase any material, it is important to be sure that it contains one of the photochromic compounds.

A photochromic material reversible color change. Image source Royal Society of Chemistry

Apparently, photochromic materials are used in many popular applications such as:

You don’t have to worry about these applications, I will discuss them in the next chapters. For now, let me have a quick overview of various technologies you can use to obtain the best photochromic surface.

2.2. Photochromic Coating

Assuming you have the right photochromic molecules; how then can you treat a surface? The photochromic lens, visors and face shield manufacturers have adopted different methods of adding photochromic molecules to surfaces.

These technologies include:

  • Co-molding
  • Coating
  • Matrix photochromic
  • In-mass technique
  • Imbibed technique

For the scope of this photochromic eBook, I will focus on the first two techniques – photochromic coating and co-molding. But before that, I will take you through a quick overview of the remaining technologies

  • Matrix photochromic

Matrix photochromic is a common technology in KODAK products. In this technique, a photochromic material is chemically bonded on the lens material. These materials are mainly used in photography and they lighten up faster.

  • In-mass technique

In-mass technique is can be a better alternative to the matrix photochromic. Here, you have to mix photosensitive material uniformly in the entire structure of the material. As a result, you will have the photochromic molecules both in and on the surface of the material.

  • Imbibed technique

The photochromic molecules are absorbed into the plastic material. As a result, the photochromic molecule becomes part of the material. This makes imbibed technique a perfect choice for surfaces prone to scratching.

With this knowledge, I think we can focus on some the most popular photochromic techniques used in visors, lenses and face shield industries.

Photochromic coating technology

Photochromic coating is a completely different approach from the three I have discussed above. You can use it for injection molded face shields, lenses and visors. Lens manufacturers such as WeeTect use a special photochromic material in the coating process.


Examples of photochromic lenses

Photochromic coating technology, is an affordable and effective way of producing light sensitive safety equipment. With this technology, we apply photochromic coating directly to the surface of polycarbonate lens, visors or face shields. Normally, this happens during the manufacturing process.

So far, when it comes to photochromic coating, you need to note the following:

  • The photochromic coating is so thin that you cannot notice whether it exists or not. In most cases, the coating is about 1 to 30 microns.
  • Polycarbonate surface is pre-treated to provide reactive groups. Without this, the coating may not stick to the surface.
  • Treating the surface may involve the use of various organic compounds such as polymerizable composition.
  • Ensure sure the surface adhesion is fully exposed ready for the photochromic coating
  • Apply the photochromic coating and let the surface cure

NOTE: Photochromic lens manufacturers are exploring different coating techniques in an attempt to adopt one that guarantees superior results.

For instance, there are manufacturers who consolidate the photochromic molecules with other substrates such anti-glare and anti-scratch. They then use either flow or dip coating; after which they opt for an appropriate curing technique such as thermo curing.


Lenses with photochromic lenses, with other technologies such as anti-reflective. Image source – Optique

In most cases, surfaces that are not properly coated will tend to peel off or get scratched with time. This basically reduces the effectiveness of the photochromic coating.

At times, photochromic coating may not offer a perfect solution for some applications. This is actually the main reason for the adoption of the second technique – photochromic co-molding. Not so many manufacturers use this technique.

So far, WeeTect is the only photochromic visors and lens manufacturer using co-molding process.

2.3 Photochromic Co-injection Molding

Photochromic co-injection molding involves three key processes:

  • Choose a high quality photochromic film/sheet and surface to be treated
  • Preform the film/sheet
  • Co-mold the parts together

Alternatively, the three processes can be summarized as shown in the video below courtesy of

BemisATG:

Don’t worry, I will expound on the above points. That was just a short summary of what this photochromic technique is all about.

So, let me start by defining the term co-injection molding.

First, let me begin by explaining the meaning of injection molding.

Injection molding is the process of shaping plastic material by heating it to a molten state, then injecting it into a mold under a reasonable amount of pressure and temperature. You can read more about injection molding here: Introduction to Injection Molding.

Below is a video of an injection molding process by Engineer guy:

Co-molding, which is also referred to as multi-component injection molding; is not different from the traditional injection molding technique. The only difference comes in the final structure of the molding process.

Adopting a co-molding manufacturing process basically aims to improve the performance and reliability of the photochromic lenses, visors and face shields.

As you can see, the photochromic substrate is sandwiched between two layers of polycarbonate sheet/plastic. This is quite clear in the co-mold part below:


Co-molding process – Image source: WeeTect

I know if you are familiar with the traditional molding process, you could be wondering how this can even be possible. Well, the photochromic co-injection molding has been incorporated in the modern manufacturing processes.

Fundamental aspects of co-injection molding

As I had stated earlier, photochromic co-molding process aims to produce one polycarbonate lens, visor or face shield part. That is, the photochromic film is sandwiched between layers of polycarbonate material.There are several photochromic co-molding machines in the market. Thou, for this photochromic eBook, I will focus on a process adopted by WeeTect. The WeeTect photochromic co-molding technology involves:

  • Making a desirable mold based on the exact shape of visor, face shields or lens to be produced.
  • Preforming to the photochromic film and polycarbonate parts into a desired design before the actual co-molding process begins.
  • At a reasonable temperature and pressure, co-mold the photochromic film and polycarbonate sheets to get the final product.

Alternatively, other photochromic lens manufacturers may opt for a multi-material hot runner to distribute different melt streams from different injection barrels to the molding gate. The gate locations are located in the mold cavity. Here, they use you will use a valve gating to regulate the flow.

Advantages of photochromic co-injection molding technique

So far, photochromic co-molding comes with the following key benefits:

  • Photochromic film is not exposed to the external environment (sandwiched between two layers) thus, it is neither affected by scratches nor degrades.
  • It’s an economical way of producing customized and price competitive photochromic lenses, visors and face shields.
  • Produces durable photochromic lenses, visors and face shields.
  • Reduces assembly operations compared to other methods such as photochromic coating.
  • Produces high quality products that do not peel off like in the case of most coating solutions.
  • It is basically a single operation, thus reducing expenses

I believe you are now familiar with various processes manufacturers use to make photochromic lens, visors or face shields.

Of course I have also defined and explained the working principle of the photochromic technology in the previous chapter. However, I won’t end this chapter before we review the photochromic effect.

2.4 Photochromic Effect

What is a photochromic effect?

I know this is a common question most clients ask every day.
A photochromic effect is a reversible change in chemical species caused by the absorption of electromagnetic radiation. That is, when photochromic materials are exposed to ultraviolet radiation, they change their structure, hence causing a change in color (from colorless to dark (tint)). In the absence of UV radiation, they retain their initial color.

At this point, I believe you now understand all the crucial facts about photochromic material, compounds, formation and properties.

In the next chapters, I will explore possible applications of photochromic materials. I am quite sure you have seen or used these products before. May be you have known them as “self-darkening” or “self-tinting” goggles/lenses.

Also, I consider the next chapter to be an important section for clients who wish to invest in the photochromic business. It act as a complete guide to choosing photochromic products for their new market niche.

Chapter : 3

Photochromic Products: What Applications are Photochromic Technology Used For

In this chapter, I will introduce you to various uses of photochromic coating technology. This will help you choose the right photochromic products for your business model or niche. The scope of this photochromic eBook will focus on the following key applications:

  • Photochromic lenses
  • Photochromic glasses
  • Photochromic visors
  • Photochromic shields
  • Photochromic goggles
  • Photochromic films
  • Photochromic windshield
  • Photochromic safety glasses

For every photochromic application listed above; I will also discuss different options available in each category. That is, you will find that photochromic lenses alone may be classified depending design, application, brand, etc.

Looking at my list of eight main products, you will realize that these are safety products. In the modern industrial and sporting setup; unobstructed view is essential to ensure every ones safety.


Photochromic goggles tint on exposure to UV radiations. They protect eyes from harmful radiations. Image source – Wikipedia

As you have seen in the previous chapters, photochromic eye wear, eliminates UV radiations that may cause eye complications. That is, the photochromic film tint in response to the UV radiations.

As the World Health Organization reports, prolonged exposure to UV radiations can lead to chronic eye problems. Furthermore, the U.S. Environmental Protection Agency urges people to take eye protection seriously to avoid eye problems such as cataracts.

In the motor racing or biking the outdoors, most people who use ordinary visor inserts, must carry different tints to protect their eyes whenever the weather changes. Apparently, this is going to be a thing of the past with the invention of high quality photochromic eye wear. They only need one photochromic accessory.

For sure, you can see the reason why I insist on investing and choosing the right photochromic product. Let’s start by discussing photochromic lenses.

3.1: Photochromic Lenses

Let me start by defining what a lens is so that you may understand what I am just about to discuss.

A lens is an optical device that either disperses or focuses a beam of light. The available lenses are mainly manufactured from polycarbonate or glass. However, polycarbonate lenses are popular for their impact resistance and shatterproof properties. They are used in IP cameras, instruments, safety wear, etc.


A polycarbonate lens – Image source Wikipedia

Glass or polycarbonate lenses are not inherently superior for most of the above applications. With a virgin polycarbonate or glass lens, you are likely to suffer from glare, fogging, scratches or harmful UV radiations. This implies, you need to treat all your lenses with right substrate or chemicals and it leads us to our next subtopic.

3.1.1 What is Photochromic Lenses?

Photochromic lens is basically an optical device with photochromic substrates. That is, they tint (turn black) on exposure to UV radiations and retain their original state (clear) in the absence of UV radiations.


Different types of photochromic lenses – Image source PolyRay

Here, I will discuss both polycarbonate and glass lenses. This will give you a wide range of options to choose from as a distributor or OEM business.

As you can remember, in the previous chapters my main focus was on the photochromic coating and co-molding technologies. So, throughout this chapter, I will mainly focus on the photochromic lenses based on these technologies.

Well, let’s start by asking this simple question:

3.1.2 How Do Photochromic Lenses Work?

The working principle of photochromic lenses is not as complicated as most people perceive. Whether you talk about silver chloride or silver halide, which were commonly used on the glass lenses or carbon based compounds such as naphthopyrans on polycarbonate lenses; the working principle still remains almost the same.

Below are two images I would like you to observe:

photochromic lens of weetect
Above are examples of photochromic lenses. Image source – WeeTect

Normally, when photochromic lens is exposed to UV radiation, we will see it change color. That is, change from colorless or transparent to dark/tint. This is change is reversible, in the absence of activating light (UV radiation). It is the visible change that any lens users will automatically see.

But, how do you justify this scientifically?

Ideally, the change involves realignment of certain molecular structure of basic elements that make the photochromic coating or molecules. You can see this from the image below.

So, on exposure to UV radiation or sunlight; a chemical process takes place where:

1. For silver chloride or silver halide

There is an oxidation-reduction reaction that takes place once exposed to sunlight/UV radiation. That is, during the process, an oxidation takes place where chlorine is oxidized to produce chlorine atoms and electron. Below is a chemical reaction of the process:

〖Cl〗^-→Cl+ e^-

The free electron is transferred to silver ions that produces silver ions as indicated in the equation below:

〖Ag〗^++ e^- →Ag

As these atoms cluster together, they cause the lens to darken, blocking harmful UV radiation

2. How naphthopyrans work

Naphthopyrans structure changes on exposure to UV radiation, resulting in the overall change of the lens. You can see this from the illustration below:


A change in naphthopyrans structure. Image source the American Chemical Society

These compounds are mainly used for the polycarbonate or plastic lenses.

In each case, the change from transparent to tinted color is always fast and “smooth”. There are so sensitive to an extent that it takes only 30 seconds to begin tinting. Furthermore, it will continue to tint/darken as the surface gets more exposure to the UV light.

These lenses come in different sizes and designs thus, the varying quality performance and pricing. The price also varies, depending on the type of photochromic lens brand (I will discuss this later in this chapter).

For now, let me focus on the photochromic lens prices first.

3.1.3 Photochromic Lenses Price

Photochromic lens price varies depending on a number of factors. These include:

  • Type of material – broadly, we have glass and polycarbonate lenses. Polycarbonate lenses tend to slightly expensive as compared to glass.
  • Technology – manufacturers may opt for photochromic coating or co-molding. Furthermore, other manufacturers may add more surface treatments such anti-fog, anti-scratch or polarized surface. All these play a significant role in determining the price of photochromic lens
  • Photochromic material – your manufacturer may choose silver or carbon based compounds.
  • Customized and design options – this may depend on the OEM business requirements.
  • Brand type – a Transitions or WeeTect Photochromic Lens may have the same properties and performance though different prices.

In short, the price of these lenses may vary depending on the above 5 factors. You can get a polycarbonate photochromic lens for as low as $35 or more. Just ensure before you make up your mind, just be sure to do a comprehensive price comparison

So, why should you buy these lenses? Next, I will take you through a quick review why you need photochromic lens.

3.1.4 Benefits of Photochromic lenses

Do you wonder why most people opt for photochromic lenses as opposed to the tinted lenses? They are not only trendy, but also have a lot of benefits with safety being a priority. It is for these reasons that I can confidently recommend the lenses for any outdoor sporting activity.

In this section, I will explain why you need photochromic lenses. Here are the key benefits you need to know:

  • Photochromic lenses guarantee comfort

During the day, sunlight tends to fluctuate a lot. This results in the expansion and contraction of the eye muscles to control the amount of light that enters the eye. Of course, this will result in a lot of discomfort as your eye muscles adjust to the outdoor environment.


Photochromic lenses guarantee comfort in all weather conditions. Photo credits – Mivision

Photochromic lenses are designed to control the amount of light that reaches the eye. They tend to regulate the amount of radiation to a nearly constant intensity by tinting or darkening. This relieves the eye muscles, hence guarantees comfort.

  • Provide an advanced eye safety

UV radiation possesses an enormous amount of energy that can cause eye problems. In fact, various reports indicate that most eye problems are due to a prolonged exposure to UV radiation.


How high quality lens guarantees safety. Photo credits – FineGlass

Photochromic lenses filter 100% of harmful UV radiations such as UVA and UVB. Therefore, your eyes will be protected from any harmful radiations.

  • Reduces unnecessary expenses and misery

Let me begin with the obvious one. Eye problems come with unbearable costs. First, you’ll spend a lot of money seeking treatment. At times, these treatments may prolong and ultimately end up spending more than 50% of your savings.


Eye problems caused unprotected lenses – Image source Jenny’s Website

Furthermore, you may be declared redundant by your employer. Thereby losing your job, which will be expensive to your dependents.

Unlike the traditional lenses where you need to carry more than one (clear and tinted) that you may change when the weather changes; one photochromic lens is enough. That is, it automatically changes from clear to tint and vice versa, depending on the weather condition. Basically, you don’t need to buy an extra lens.

  • Photochromic lens is convenient

You don’t have to stop by the roadside or stop journey changing lenses. This is really unconvincing, especially if you are a sporting activity.


A complete insight on how lenses with different treatments can protect your eyes. Image source – Examined Living

The photochromic lenses will automatically change depending on the outdoor environment. So, you will have all the time to worry and focus on the work at hand instead of your lenses.

  • It is a versatile accessory for all weather conditions

Apart from the UV protection, the modern photochromic lenses include a number of coatings such as: anti-scratch, anti-glare, polarized surface, hydrophobic and anti-fog solution.

This implies, whether you use the photochromic lenses in fluctuating weather conditions, they won’t fog. Moreover, hydrophilic coating helps to remove dust or oil stains faster.

  • Cost competitiveness for OEM business

Venturing in the photochromic lens business when you have identified a company that specializes in OEM production can be profitable. For a fact, the demand for these lenses has increased in the recent past. So, there is a ready market for these products.Apart from these advantages and benefits of photochromic lenses, there are three key disadvantages that manufacturers are trying to reduce their effect.

  • High photochromic performance

These lenses are designed with high quality photochromic molecules that guarantee safety. They are darken and fade faster. That is, all these changes take place within a few minutes.

In short, for people who engage in outdoor activities, photochromic lens is one accessory you cannot survive without. It is even crucial if you wish to achieve the following: protection from UV radiation, comfort and convenience

Since you started reading photochromic guide, it is quite clear that this product offers so many advantages. I will review them in the next section to for an easy and quick understanding.

3.1.5 Disadvantages of photochromic lenses

Photochromic lenses are safe for any outdoor activity. However, there are certain challenges you may face, especially when you’re going to use the lenses for application that require fast reacting safety accessory.

Below are three disadvantages of photochromic lenses:

  • Slightly slow response time

These lenses begin to change color after about 5 minutes. That is, to change from clear to tint and vice versa. Therefore, they are not suitable for applications that require fast response time such as welding. A reason why some accessories such as auto darkening welding helmets become handy.

  • May not be effective in cars

Unless you go for special photochromic lenses, the standard ones may not tint or darken since there no enough UV to activate the tinting process.

  • Photochromic lenses price

Surprisingly, you will find photochromic lenses that cost as high as $200 or even more. Thou, this varies depending on the type of brand. So, be sure to shop for one that is affordable and does not compromise quality.

At this juncture, I am sure you can make the right choice in case you need a photochromic lens. However, before I summarize this section, let me take you through a quick summary of different types of photochromic lens brands available in the market.

3.1.6 Photochromic Lenses Brands

You should buy only the reputable photochromic lens brands. This is because they are of high quality and reliable. These brands include:

Transitions

Transitions is a popular brand in the photochromic lens market. In fact, you’ll find many people referring to photochromic lenses as transitions lenses. The company has strived to market the brand name since 1990.


Transitions photochromic lens

Examples of transitions brand include: Transitions Signature, Transitions XTRActive and Transitions Vantage, just to mention a few.

WeeTect

Since 1993, WeeTect has produced a number of optical lenses with a number of technological innovations and advancements. WeeTect unveiled their WeeTect Photochromic Technology (WPT) where it focuses on photochromic coating and co-molding.

WeeTect Photochromic

WeeTect mainly focuses on OEM business with their photochromic lenses. The company mainly manufacturers polycarbonate lenses.

Sensity

Sensity is yet, another photochromic lens brand available in grey and brown colors. These lenses feature anti-reflective coating and photochromic technology.


Sensity photochromic lenses

At times, the Sensity lenses may also be referred to as the Hoya Visions Care Lenses. Hoya is a Japanese company that was established in 1941.

Essilor Sun Solution

The company sells a number of sun lenses that range from photochromic and semi-finished (Rx). These lenses are also sold under the brand name, BNL Sun Lenses


Essilor Sun Solution photochromic lenses

These photochromic lens brand feature a unique technology – Active Cell Technology. Furthermore, the lenses are also available in polycarbonate, polarized, non-polarized and NXT technologies.

Zeiss

Zeiss is an international company that has ventured in optics and optoelectronics. Zeiss lenses are used in a wide range of eye care safety equipment and measuring machines such as medical technology, microscopes, measuring technologies, etc.


Zeiss photochromic lenses

Zeiss is basically divided into the following business groups: Microscopy, Consumer Optics, Metrology, Medical Technology, Vision Care and Semiconductor Manufacturing Technology.

Rodenstock

Rodenstock is a known brand that has ventured in a number of sunshine and artificial light, shade and light sensitive lenses. The company is known for its unique ColorMatic IQ® lenses that are self-tinting.


Rodenstock photochromic lenses

To cater for the wide range of market demands, Rodenstock lenses are available in pure gray, racing green and chocolate brown.

Signet Armorlite

Signet Armorlite is a reputable photochromic lens brand. These photochromic lenses feature their unique and innovative technology – PhotoViewsTM.


Signet Armorlite photochromic lenses

Though Signet Armorlite mainly focused on glass lenses, the company has unveiled polycarbonate lenses. This includes their KODAK Progressive Lenses.

These are only seven photochromic lens brands. For a fact, there are many brands in the market. However, quality and reliability is key when purchasing these lenses.

You’ll realize that every manufacturer strives to provide a better solution and unique features that enhance performance and durability. Moreover, you have also noticed that every photochromic lens brand feature a unique technology such as the PhotoViewsTM for Signet Armorlite, WeeTect Photochromic Technology for WeeTect, ColorMatic IQ for Rodenstock, etc,

Now, I am sure you can confidently shop for the right photochromic lenses.

Next, I want to introduce you to another popular photochromic product – photochromic glasses. At times, if you’ll opt for glass lenses by any chance you can’t get the polycarbonate lenses.

3.2 Photochromic Glasses

Do you participate in outdoor activities such as cycling, hiking, riding, skiing or running? Which type of safety gear do you use?

I am sure most of you will opt for tinted glasses, which are actually inconveniencing. Such glasses do not adjust based on the environmental conditions.

Photochromic glasses with quality silver or naphthopyran compounds, are highly recommended for any outdoor activity. On exposure to the sun’s UV radiation, they tint, reducing their harmful effects. Otherwise, there will be no change in color.

Of course, this is based on a simple working principle that I will explain shortly. Presently, photochromic glasses come in a wide range of configurations and designs such as photochromic eyeglasses, photochromic cycling glasses and photochromic sunglasses.

3.2.1 How does Photochromic Glass Work?

As I had mentioned earlier in this photochromic eBook, the working principle of photochromic glasses depends on the reaction of photochromic molecules. These photochromic molecules cause the glass to tint.

You’ll find some photochromic glass manufacturers using silver or naphthopyran compounds. Even though the compounds tend to react differently to UV radiations, they still achieve the same objective

That is, your photochromic glass will turn from clear to tinted, and vice versa.

Let me take you through a quick review of this process:

Silver compounds (silver chloride)

This is where a reversible chemical reaction takes place in the presence and absence of UV radiation. It is basically a redox (oxidation-reduction) reaction. You can see this from the equations below:

〖Cl〗^-→Cl+e^- …Oxidation reaction.
〖Ag〗^++e^-→AG …Reduction reaction

Again, for a photo-oxidation process, to take place, photochromic glasses manufactures use both silver chloride (AgCl) and copper chloride (CuCl). The copper chloride helps in the reversal process. This results in the following equations:

Cl+〖Cu〗^+→〖Cu〗^(+2)+〖Cl〗^-
〖Cu〗^(+2) Ag→〖Cu〗^(+1)+〖Ag〗^+

Naphthopyran compounds

For photochromic glasses with these compounds, the process basically involves a change in molecules structure. I had explained this earlier, you can refer to section 3.1.2.

Now, with all these in mind, I want to focus on specific types of photochromic lenses. This will mainly be based on the type of outdoor activities such as motorcycle, running, cycling, shooting, etc.

3.2.2 Photochromic eye glasses

I know at times, you may be overwhelmed by the wide range of photochromic eye glasses available in the market. Whether you’re looking for stylish or safe eye glass that block 100% UVA and UVB; these are the only safety gears to trust. As you can see from the image below, these lenses progressively tint on exposure to the UV radiations thereby, blocking all harmful radiations.


An image showing how photochromic glasses tint progressively on exposure to UV radiations. Image source – Glass World

You will also notice the degree of tint of photochromic eye glasses varies depending in the amount of silver compounds embedded on the glass during the manufacturing process. For a fact, every photochromic eye glass manufacturer strives to use superior photochromic compounds.

Again, in case you are suffering from specific eye problems, it is important to consult an optician before purchasing these photochromic eye glasses.

Another key application of photochromic glasses is:

3.2.3 Photochromic cycling glasses

Cycling is an outdoor activity that requires every individual to have a clear view all the time. I know you’re familiar with various challenges associated with unpredictable weather during spring. This is not limited to bright sunlight, fluctuating temperature and humidity.

In this case, you need photochromic cycling glasses with anti-fog, iridium, anti-scratch and hydrophobic coating. The photochromic cycling glass tint adjusts from dark to bright, depending on the environmental weather conditions.


A cyclist wearing photochromic cycling glasses during sunny weather to protect the eyes from harmful UV radiation and bright light

The modern photochromic cycling glasses come in different shapes and designs. Some photochromic glasses are designed to fit with the cycling helmet. Such designs protect them from falling.

With a high quality photochromic cycling glass brands, you don’t need interchangeable lenses. Your eyes will be safe from changing weather conditions, wind, debris, rains and insects.

Next in my list is the photochromic sunglasses.

3.2.4 Different Photochromic Sunglasses

I know you’ve used photochromic sunglasses at some point. You must have appreciated that fact that the sunglasses could tint when outdoors. Obviously, these safety accessories guarantee the numerous benefits I listed in chapter three of this photochromic eBook.

There are so many eyewear in the market. Mostly, people even find it difficult to choose the right one for outdoor activities. Perhaps, they don’t know the exact specifications to look for in these safety equipment. Don’t worry, I will explain everything.

So, what are photochromic sunglasses?

First, a sunglass is a safety eyewear that prevents high energy light or bright sunlight from reaching the eye. This causes discomfort and in extreme situations, it may damage the eye.


Sunglasses

Over the past years, sunglass manufacturers have improved performance and reliability of this safety equipment. A reason why modern sunglasses feature photochromic substrates, anti-scratch coating, anti-fog coating, hydrophobic coating, iridium coating etc.

The sunglasses I am going to discuss in this section have photochromic molecules added to the lens using appropriate technologies such as coating, co-molding, etc.


Different types of photochromic sunglasses. Image source – WIRED

You’ll realize that sunglasses may have different features, making them appropriate for a specific application. Below are different types of photochromic sunglasses:

Photochromic sports sunglasses

Photochromic sports sunglasses are designed to boost visual contrast in all environments during any sporting activity. Whether you’re cycling, skiing, riding or running; photochromic sports sunglasses will protect your eyes from bright sunlight or high energy radiations that may impair vision.


Photochromic sports sunglasses. Image source – ORAO

Modern photochromic sports sunglasses feature other coating technologies such as anti-fog, hydrophobic, anti-scratch. This ensures all your sports sunglasses guarantee optimal performance in all weather conditions.

Unlike the polarized sunglasses that remain permanently black or tinted, photochromic sunglasses degree of tint varies with the prevailing weather conditions. That is, as the intensity of sun’s energy radiation or brightness reduces, they begin to turn clear again.

This basically improves depth perception and your eyes won’t strain. With these photochromic sports sunglasses, you don’t have to carry an extra glass or worry about the changing weather conditions. You’ll only focus on perfect your skills.

Spots sunglasses come with sturdy frame and shatterproof lenses. The sunglasses are designed for a perfect fit that guarantee comfort. They are also durable and stylish.

You need to go for photochromic sports sunglasses with sport-specific features. That is, if you’re a hockey player or cyclist; looking for a specific photochromic sunglass brand designed for that activity is ideal.

Moreover, you need to evaluate various technologies available as each photochromic sports sunglass brand features unique technology. For instance, Liberty Sports offers AutoFit and Powered by Switch technologies. On the other hand, Oakley photochromic sunglasses feature High Definition Optics technology.

Photochromic polarized sunglasses

Photochromic polarized sunglasses are an essential eyewear for water activities such as skiing, fishing, snorkeling, scuba diving, etc. These sunglasses feature two essential technologies – photochromic and polarization.


Lense for photochromic polarized sunglasses

So, I am going to tell you why these lenses are a perfect choice for most outdoor activities.
First, the polarized surface will reduce glare. Glare is a phenomenon that will make it nearly impossible to see in the presence of bright light. However, polarized surfaces will not protect your eyes from harmful UV radiations.

Secondly, to make sunglasses safe for your daily use, glass manufacturers incorporate photochromic molecules on the sunglass. Therefore, your lenses will sunglass will automatically tint to filter out all harmful radiations that may cause eye problems.

Clearly, you can see the photochromic polarized sunglasses come with two main benefits. Remember, these lenses may have other coatings such as anti-fog and anti-scratch.

The photochromic polarized sunglasses increase visual comfort, enhance contrast for ground level objects, make it easy to see through the water and reduce eyestrain.

In short, these unique technologies make sunglasses convenient and adaptable to the most devastating weather conditions. As long as you acquire sunglass with high performance photochromic and polarized surface; your safety is always guaranteed.

Photochromic cycling sunglasses

As a cyclist, you need quality photochromic cycling sunglasses to protect your eyes from the sun’s ultraviolet radiation. Cycling involves traversing different regions with varying weather conditions. In most cases, you will hardly predict the weather, especially during spring. It could be sunny one minute and cloudy the next.

Therefore, without an eyewear that can resist fog, control sunlight intensity and eliminate glare; chances of getting involved in accidents are quite high. Photochromic cycling sunglasses have light-sensitive substrates, for a seamless tinting when outdoors (on exposure to UV radiation). Again, as the intensity of the sun’s UV radiation reduces, the tint begins to fade.


Figure 1Photochromic cycling sunglasses. Image source – road.cc

The tinting and fading processes are automatic. So, the photochromic cycling sunglass does not require your intervention. All you need is a cycling sunglass with a high performance photochromic molecules.

This is unlike the tinted cycling sunglasses, where you’ll have to change the lens frequently. For the tinted sunglasses, you’ll be forced to buy more than two, depending on your terrain. This is quite inconveniencing and expensive.

Don’t forget to consider the design too. Aesthetics matter a lot. I am sure, it is your desire to have a stylish and comfortable photochromic cycling sunglass. So, do a proper market research to choose the right photochromic cycling sunglass brand.

Photochromic motorcycle sunglasses

To protect your eyes from the ultraviolet radiations during summer, you need photochromic motorcycle sunglasses. Even when the weather is unpredictable, these motorcycle sunglasses will filter all the harmful UV radiations

Blinding light of the sun is one of the key challenges you’ll have to deal with when riding for long distances. Besides, unnecessary reflections may also put your life at risk. It is actually for this reason that you need to acquire a quality photochromic motorcycle sunglasses.


Figure 1A photochromic motorcycle sunglass. Image source – Prescription Motorcycle Glasses

I know there other safety gears such as tinted motorcycle visor inserts, however, they may not be convenient and reliable in situations where the weather conditions keeps fluctuating. Remember, a tinted motorcycle visor will maintain its color, whether in sunny or cloudy environment.

Photochromic running sunglasses

I know running is a tedious sporting activity where you’ll be exposed to scorching sun, fluctuating humidity and temperature, among other hostile weather conditions. In such situations, you need a good safety gear that can protect your eyes from all these devastating weather conditions.


Photochromic running goggles. Image source – The Independent

That is, you need a photochromic running sunglasses. They automatically adjust to the changing light conditions. Through this, they filter all harmful radiations allowing only a sufficient amount of light to pass through. As a result, this guarantees enhanced eye safety. In addition to these, photochromic running sunglasses may have other coating such as anti-fog, anti-scratch or anti-glare coating.

As you shop for a specific sunglass, always go for the reputable brands since they are manufactured to meet high quality standards.

From the above examples, it is quite evident that you will find a photochromic sunglass for nearly any application. You can visit various online stores to choose from a wide range of options available in the market. This will also give you a chance to compare prices.

Before, I wrap up this section, let me discuss the photochromic shooting glasses and photochromic reading glasses.

3.2.5 Photochromic shooting glasses

Shooting is a popular outdoor activity that requires accuracy and concentration. You’ll will be exposed to high energy ultraviolet radiations, light reflections, mist/fog, dust, etc. All these will make it nearly impossible to have a clear vision of your target.

So far, only photochromic shooting glasses can protect you from this devastating weather conditions. The shooting glass comes with a lens that adjusts accordingly with an increase in the intensity of light.


Photochromic shooting glasses – Image source Stag Arms

In the absence of activating light (UV radiations), the photochromic shooting glasses will maintain their natural state (color). Nonetheless, on exposure to the ultraviolet radiation, it will begin to tint automatically. This is a reversible process.

In addition to these, modern photochromic shooting glasses feature other technologies such as polarized surface, anti-scratch and anti-fog. All these aim to guarantee perfect vision.

These photochromic shooting glasses come in a super lightweight and stylish design. They are comfortable and adjustable for the dynamic demands of the shooters.

As you shop for photochromic shooting glasses, remember to evaluate the existing technologies. Most shooting glass brands come with unique photochromic technologies that offer a wide of benefits.

3.2.6 Photochromic reading glasses

Photochromic reading glasses will protect your eyes from fluctuating ultraviolet radiations and reflection. The degree of tint varies with environmental weather conditions. Whether you’re indoors or outdoors in a cloudy or sunny day, the photochromic reading glasses will adjust accordingly.

You can conveniently enjoy your studies outdoors without worrying about effects of bright light from the sun or glare.


Photochromic reading glasses. Image source – Qwerkity

To enhance the performance of photochromic reading glasses, apart from the photochromic compounds; the glasses have anti-reflective, anti-glare, anti-scratch, anti-fog and hydrophobic coating. However, not all reading glasses will have all these coatings. Always consult your manufacturer or a specialist in reading glasses, to know the capability of your reading glasses.
Again, when it comes to choosing a suitable photochromic reading glasses; it is advisable to consult an optician. This is to avoid eye complications associated with choosing substandard lenses.

3.2.3 Photochromic Glasses Price

In section 3.1.3 of this chapter, I discussed certain aspects that determine the price of photochromic lenses. Well, some of these factors are closely related.

You could actually use them as a photochromic glass buying checklist. This is because every aspect that determines cost also influences performance of the photochromic glass.

The main factors that determine photochromic glass prices include:

Photochromic glass brands

There are different photochromic glass brands in the market. Being a free market, you’re likely to find reputable brands going for a relatively high price. The new brands may sell at a lower price as they strive to capture the market. But, you shouldn’t settle for cheap photochromic glasses since some are low quality products.

Type and number of coating

The glass coating directly determines both the performance and cost. You should know that photochromic molecules/substrate/coating alone, is not enough to guarantee safety. Well, your lens will protect you from adverse UV radiations, but it may still fog up or be susceptible to glare. So, you should have all these in mind.

For a fact, photochromic lenses with more layers of coating are likely to be more expensive.

Nature/type of the lens

Photochromic sunglasses can be manufactured from different materials such as glass, NXT polyurethane, polycarbonate and acrylic. Of course, each material has its unique pros and cons hence, the variation in price.

Type/nature of the photochromic glass frame design

First, the type of materials used to construct photochromic glass frame will determine the unit cost of these safety equipment. They are mainly constructed from metal, nylon or plastic.

Secondly, the type of design will also determine the unit cost of the photochromic lens. Complex or sophisticated designs will be more expensive than simple ones.

Lastly, you need to consider the demand and supply forces. They are integral factors that also determine prices of these photochromic glasses. That is, when the demand is high, you should expect prices to go up.

With all these in mind, I am sure you can choose the right photochromic glasses or sunglasses for your specific applications. In our next section, I will discuss the various types of photochromic visors available in the market. I will highlight various key features of every safety equipment that you know.

3.3 Photochromic Visor

Various safety organizations and government departments such as the Occupational Safety and Health Administration (OSHA), have strict rules and regulations when it comes to eye and face protection. This is due to the increased number of eye and face accidents reported in the recent past. Surprisingly, a larger percentage of the victims did not have the appropriate safety gears at the time of the accidents.

To curb this, a number of visor manufacturing companies have invested in better technologies. These range from choosing the specific materials such as polycarbonate sheet as opposed to glass. Furthermore, the companies have adopted better coatings such as anti-fog, photochromic, anti-scratch, iridium and hydrophobic coating.


Examples of photochromic visors. Image source – WeeTect Material Ltd.

The R&D led to the development of versatile eye and face safety equipment such as the photochromic visors. In this section, I will introduce you to four main types of photochromic visors – photochromic motorcycle visors, photochromic helmet visors, photochromic visor inserts and photochromic motorcycle helmet.

These are not the only types of visors available in the market. Like the photochromic sunglasses and lenses, photochromic visors are classified depending on the specific nature of applications. These may include hockey visors, full face respiratory visors, football visors etc.

Photochromic motorcycle visor

The technological advancements you’ve witnessed in the recent past aim to guarantee safety, whether the riders are on a racetrack or having fun. Unlike the traditional motorcycle visors that were either tinted or clear; the photochromic motorcycle visors are designed to tint progressively on exposure to the ultraviolet radiations.

That is, your photochromic motorcycle visors will automatically adjust the degree of tint depending on the changing light conditions. So, you don’t have to carry an extra visor or stop to change the visors. It is not only a tiresome process, but also inconveniencing and time consuming.

As you can see, these photochromic visors are slightly different from the traditional ones that had anti-fog, anti-scratch or iridium coating.


Motorcycle visors without photochromic coating. They are tinted, which can be inconveniencing as they’ll maintain the color tint throughout the riding period. Image source – WeeTect Material Ltd

They are designed to integrate all these coatings, alongside the photochromic property that optimizes vision. These photochromic molecules are added by either coating or co-molding.

Clearly, a photochromic motorcycle visor is a perfect choice for all your dynamic riding needs. They come in versatile designs that can fit any motorcycle helmet. In fact, these photochromic visors are not different from the ordinary visors you’re used to. Both shape and design are the same except for the photochromic technology that has been integrated.

Photochromic helmet visor

Photochromic Visor

You can classify photochromic helmet visors based on their specific applications. That is, there’re motorcycle helmet visors, football helmet visors, hockey helmet visors, etc. As you all know, most sporting activities come with potential risks that may lead to death or serious face and head injuries. This is quite common for players who don’t have the right safety equipment.

Photochromic helmet visors have transformed the safety industry by optimizing vision and ensuring eye safety. Photochromic visors tint in the presence of excess UV radiation (bright light) and retain the original color of the lens in the absence of this light.


A photochromic helmet visors. Image source – Wikimedia Commons

This eliminates all harmful UV radiations that may cause damage to your eyes. Again, with the photochromic helmet visors, you don’t have to shuffle two or more different helmet visors as the intensity of sunlight varies. These helmet visors will automatically adjust the degree of tint. Remember, this will save you from buying an extra helmet visor

Therefore, you can confidently use a photochromic helmet visor at any time of the day without worrying about your safety. The photochromic helmet visors come in different designs and configurations. They may have other coatings to enhance performance such as eliminating fog, scratches and glare.

Photochromic visor insert

Photochromic visor inserts will solve all your visibility problems. It is a thin plastic film with photochromic compounds that makes it adjust to the changing sun’s brightness or UV radiation.

Quite a number of people confuse photochromic visor inserts with thin films used to tint lenses. No, these are two different accessories. Here is what I am talking about:

anti fog visor insert
Two types of helmet visor inserts. Image source – WeeTect Material Ltd.

One of the key reasons for the invention of visor inserts was to eliminate the fogging problems in helmet visors. This is actually possible by stabilizing the temperature between the outer and inner surface of the helmet. You can learn more about visor inserts here.

With a photochromic visor insert, you’ll eliminate the fogging problem, while maintaining a clear view at all times. That is, your visor insert will automatically tint on exposure to ultraviolet radiation from the sun thereby protecting you from eye damage. This is a reversible process.

Whether you own Pinlock or WeeTect, you’ll realize that installing visor inserts, thou a simple process it is time consuming. You may not have that time in a racing competition. This is where a photochromic visor insert becomes handy, you don’t have to replace it in case the weather changes.

Photochromic motorcycle helmet

Photochromic motorcycle helmets adjust to the varying light conditions – they darken/tint on exposure to sunlight and clear in low light conditions. That is, your photochromic motorcycle helmets will be clear (maintain initial color) when indoors and begin to tint while outdoors.

For this reason, you don’t have to change your motorcycle helmet whenever there’s a change in weather condition. Whether you’ll be riding at night or during the day.


A photochromic motorcycle helmet. Image source – Wikipedia (Bell Sports)

For better performance, these motorcycle helmets feature different types of coating such as anti-fog, hydrophobic, iridium and anti-scratch. These basically enhance the performance and reliability of photochromic motorcycle helmets, even in the most devastating weather conditions.

As an individual who is safety conscious, you should acknowledge that your vision is critical. In fact, quite a number of motorcycle accidents are attributed to poor or blurred vision due to low quality helmet visors.

These photochromic motorcycle helmets are available in different configurations and designs. Therefore, you’ll have an opportunity to choose one that suits your riding needs. Remember, photochromic motorcycle lenses are not the traditional types that were either tinted or clear. Such motorcycle helmets are inconveniencing, especially if you’re that individual who traverse regions with varying weather conditions.

Clearly, you can see there are very many types of photochromic visors to choose from. It will all depend on your specific requirements and type of sporting activity.

Another essential safety accessory is the photochromic face shields.

3.4 Photochromic Shield

Using high quality and reliable face shield will protect your eye and face from unnecessary injuries. Broadly, the classification of face shields is based on a number of factors such as applications, nature of the coating, design, etc.


A face shield. Image source – WeeTect Material Ltd.

This section of this photochromic eBook will mainly focus on two types of face shields. These include the photochromic face shield and photochromic helmet shield. These shields possess photochromic molecules to optimize vision. I am sure, you have used one of them at one point in life.

Photochromic face shield

Depending on the task at hand, you can choose from the following types of shields – safety, UV, bionic, sanitary, ballistic, riot and medical face shield. Each face shield is manufactured to the highest quality standard, with most manufacturers opting for polycarbonate material. That is, they have to conform to the ANSI and EN standards.


Images showing how photochromic lenses tint from clear to dark. Remember, this process is reversible. Image source – WeeTect Material Ltd.

Even though most safety face shields have anti-fog, anti-scratch, iridium coating and hydrophobic coating; they may not be 100% safe without photochromic substrates. It is for this reason that safety equipment manufacturers started investing in photochromic face shields.
These face shields are designed to automatically adapt to the varying light conditions. In case you have used photochromic face shields before; I am sure you realized that they darken on exposure to sunlight (outdoors) and the tint clears as the intensity of the light reduces (indoors).

Photochromic face shield ensures a desired amount of light reaches the eye surface. Therefore, your manufacturer must conduct all the possible tests to ensure the photochromic molecules are distributed evenly on the surface of the face shield. Most of them have adopted co-molding and coating technologies as reliable ways of introducing photochromic compounds on the face shield.

Photochromic helmet shield

Motorcycle racing, hockey or football are some of the most fascinating activities. Obviously, as a player you’ll only enjoy them with an appropriate safety equipment such as photochromic helmet shield.

You’ll focus more on showcasing your talents without worrying about the effects of abrupt changes in weather conditions. Too much light, fog or glare will result in a blurred vision.


The above image illustrates how Shoei photochromic helmet shield changes on exposure to different weather conditions. Image source – Shoei Store

Photochromic molecules on these shields make them suitable for any outdoor activity. The tinting will automatically adjust as the weather changes. That is, an increase in light intensity or UV radiation will trigger a chemical process that will cause the surface to tint. The degree of tint becomes dark as the intensity of light/UV increases. Again, as sun’s UV radiation decreases, the photochromic helmet shield begins to change from dark to clear. This is a reversible process that is convenient and reduces the expense of buying two helmet shields.

It is a reliable, convenient and cheaper options compared to the tinted helmet shields.

Apart from the photochromic glasses, photochromic visors and photochromic shields; photochromic goggles are essential safety equipment I will review in the next section. At times, you can use the goggles instead of the other three accessories I have discussed above.

3.5 Photochromic Goggles

WeeTect anti fog photochromic goggle

Above are two types of photochromic goggles. Image source – WeeTect Plastic Ltd

I know you’re looking for a safety goggles that offer better protection even in the devastating and changing weather conditions. Most people mainly focus on eliminating fog, glare and scratches. Rarely will you find end users focusing on eliminating ultraviolet radiations.

It is due to this that a number of people have developed eye problems due to exposure to ultraviolet radiations. Fortunately, with the right safety accessory such as photochromic goggles; this should be a thing of the past.

 In the previous chapters of this photochromic eBook; I have discussed how photochromic molecules regulate the amount of eye reaching the eye surface. Whether you opt for glass lens or polycarbonate goggles lens, your manufacturer should adopt an appropriate technology that optimizes performance and guarantees reliability.

Like other photochromic products, photochromic goggles can be classified depending on the nature of technology, application and design. Here, I will focus on six different types of photochromic goggles. These goggles include:

  • Photochromic ski goggles
  • Photochromic snowboard goggles
  • Photochromic mountaineering goggles
  • Photochromic motorcycle goggles
  • Photochromic anti-fog goggles
  • Photochromic polarized goggles

These are just a few examples of photochromic goggles. As I stated previously, the name of these safety accessories can be coined depending on the specific nature of the application.

I’ll have a quick overview of these seven types of photochromic goggles. But first, you may watch this video by WeeTect Material Ltd. It will give you an insight of the different types of technologies that have been adopted so far in the industry to improve performance and reliability of these goggles.

Photochromic polarized goggles

As you can see from the name, this lens features two technologies – photochromic and polarization technology. So far, I believe you now understand how photochromic technology works. This is a chemical process that results in a change in the molecular structure of photochromic compounds on exposure to ultraviolet radiation (outdoors or high sunlight intensity); causing them to turn from clear to black. In the absence of this light, the photochromic polarized goggles maintain their initial color (before exposure to UV radiation and the subsequent tinting process).

Glare impairs vision. Glare is due to the reflection of light, that is, when light rays bounce off a surface. To reduce this, photochromic polarized goggles manufacturers use special chemicals that eliminate glare.


A polarized surface

However, to provide an outstanding clarity in different environments, the photochromic polarized goggles may feature other coating such as anti-fog, anti-scratch, anti-fingerprint and hydrophobic coatings.

With these, your photochromic goggles will perform incredibly well in all weather conditions. This reduces chances of accidents that may be due to poor vision.

The photochromic goggles manufacturers use different techniques to introduce these coatings to the goggles surface. Broadly, they have adopted co-molding and coating technique.

From experience, these are goggles that are comfortable and safe as your eyes won’t strain anymore. The polarization and photochromic guarantee superior performance and you can trust them during cloudy, humid or sunny days.

Broadly, the term “photochromic polarized goggles” is a broad term you may use to refer to these safety accessories. Still, the goggles can be classified based on specific applications like in the case of these other five types of goggles.

Photochromic ski goggles

Skiing is an interesting sporting and recreational activity. However, it is associated with several risks, especially if you don’t have the right ski goggles. For a fact, I have never seen anyone who engages in this outdoor activity without goggles.


Photochromic ski goggles will protect you from the fluctuating environmental weather conditions. Image source – Adventure Jay

In case you’re planning to ski down the slope, I will recommend photochromic ski goggles. Photochromic goggles will not only protect your eyes, but also enhance your performance. In most cases, you’ll find people choosing between photochromic sunglasses or photochromic goggles.

For this sporting activity, I will recommend photochromic ski goggles. Here are key reasons:

  • Photochromic molecules block 100% of the harmful ultraviolet radiations since the goggle will automatically adjust its tint depending on the intensity of light.
  • Polarized surface eliminates any form of glare that is common in snow prone environments.
  • Anti-fog eliminate fogging problems, thus, goggles will remain clear irrespective of the variation in relative humidity and temperature.
  • Hydrophobic coating prevents dust and greasy stains from sticking to the photochromic ski goggles surface making it easy to clean.
  • Anti-scratch coating protect goggles from scratches during cleaning or when you happen to fall.
  • They are designed to cover a larger section of the eye, isolating it from the external environments, thereby providing better protection that the sunglasses.

Apart from these, you’ll find photochromic ski goggles available in different designs and colors. Moreover, with the above critical features, your ski goggles will definitely provide unobstructed vision irrespective of the weather condition.

For sure, you have every reason to buy photochromic ski goggles as an essential safety accessory if you’re a skiing enthusiast.

Photochromic snowboard goggles

Being a sporting activity that is commonly practiced at high altitudes, your eyes are subjected to more ultraviolet radiations. Besides, the reflection on snow is usually too much. Leave alone the wind that may also blow ice particles to your eyes.

The bottom line is, you must have a quality safety eyewear that can protect you from these fluctuating weather conditions. It is for this reason that you’ll be advised to have the right snowboard goggles. So far, photochromic snowboard goggles with anti-fog, anti-scratch, hydrophobic and anti-glare coating is a perfect choice.


You need to have appropriate safety gear when snowboarding. Image sources – UWM

The photochromic snowboard goggles come in different shapes and designs. They may feature the following:

  • Either a cylindrical or spherical lenses, mainly manufactured from polycarbonate material..
  • Ventilation systems such as vents with high-end photochromic snowboard goggles having battery operated fans.
  • Photochromic molecules that block all the harmful ultraviolet radiation (UVA, UVB and UVC). They automatically change their tint depending on the intensity of the UV radiations.

In addition to these, you need to buy a photochromic snowboard goggle that fit perfectly only your face and can be used with a head helmet. Remember, a helmet is also an essential safety accessory that will protect you from any head injuries in case of an accident.

Photochromic mountaineering goggles

Mountaineering is an adventurous activity. You’ll get the opportunity to explore amazing natural features found at the top of high mountains. However, this activity is associated with significant

risks. The risks range from falling stone or dust particles, fluctuating ultraviolet radiation, fogging and glare just to mention a few.

For these reasons, you need to acquire a high quality photochromic mountaineering goggles. At times, you may find other people opting for photochromic sunglasses, however, going specifically for photochromic mountaineering goggles is a better option.


Photochromic goggles. Image source – WeeTect Material Limited

As you climb up the mountain, for every 1000 meters, the intensity of ultraviolet radiation increases by 10%. You can learn more about this relationship here. Moreover, every snow will act as a mirror, increasing the intensity of glare. All these may cause eye problems, especially if you climb mountains more often. This could lead to premature ageing and a number of eye problems.

To be safe, you need photochromic mountaineering goggles that block 100% of ultraviolet radiation. The tint will change depending on the degree of ultraviolet radiation.
At times, photochromic molecules alone may not be enough. This is why you may go for photochromic mountaineering goggles with anti-glare properties. The mountaineering goggles should have a polarized surface. Therefore, you should have the best eye protection equipment at all times.

Again, your photochromic mountaineering goggles should be impact resistant. So, go for those manufactured from polycarbonate sheet.

Photochromic motorcycle goggles

You can’t ride a motorcycle without an appropriate safety gear. So far, I have discussed a number of safety accessories such as photochromic motorcycle helmet visors, sunglasses and visors. In this section, I will introduce you to yet another important safety equipment. This is the photochromic motorcycle goggles.


Photochromic goggles

Like other photochromic safety accessories, photochromic motorcycle goggles are self-tinting. They tint in the presence of sunlight (UV radiation) and retains their original color (become clear) in the absence of ultraviolet radiation.

Unlike the tinted motorcycle goggles that cannot be used at night, you will comfortably use the photochromic goggles at night since they will return to their clear state. Therefore, you don’t have to carry an extra goggle.

The truth of the matter is, photochromic motorcycle goggles are superb for all bikers, irrespective of the weather condition. You don’t have to worry about the costs and risks associated with the traditional tinted goggles.

At times, you may wear these photochromic motorcycle goggles with helmets. In such situations, the goggles may not tint. This is because the tint is influenced by the existence of UV radiations. When worn behind the motorcycle visors, all UV will be blocked from reaching its surface, hence no noticeable reaction.

Photochromic anti-fog goggles

At times, photochromic compounds may not provide sufficient safety. This is the main reason most safety goggles manufacturers consolidate a number of technologies.


A photochromic goggle with anti-fog substrates. Image source – WeeTect Material Limited

The photochromic anti-fog goggles may also have other coatings such as anti-fog, anti-scratch, hydrophobic and iridium coating, just to mention a few. All these aim to improve vision in all weather conditions.

As mentioned earlier, photochromic molecules cause these goggles to tint in the presence of ultraviolet radiation and clear in the absence of ultraviolet radiation. This tinting process is reversible. This eliminates all the harmful UV radiations.

Photochromic anti-fog goggles have anti-fog coating on the inner section. This anti-fog is mainly hydrophilic substrates. You can learn more about hydrophilic properties here. Fogging is a phenomenon that occurs as relative humidity and temperature fluctuate. It is so frustrating to own motorcycle goggles that fog up.

In short, when you purchase a photochromic anti-fog goggles, you’ll be guaranteed of clear vision all the time.

Of course, there are other photochromic goggles that I have not mentioned in this photochromic eBook. What I want you to understand is that, all goggles available in the market have more than one surface treatment. There’s no one single coating or substrate that possesses all the desirable features you may want safety goggles to possess.
Our next application of the photochromic technology is photochromic films. These films are popular in industrial and domestic applications. Keep reading to learn more about these products.

3.6 Photochromic Film

Photochromic technology is popular across very many industries. In chapter three of this photochromic eBook, the main focus was mainly on the photochromic safety equipment.

In this section, I want to introduce you to a unique application of photochromic technology called photochromic films. Photochromic films are popular in the automotive, building construction and decoration industries.

First, I will focus on using photochromic tint films in the building and construction industries. This may include tinting or decorating both commercial and residential buildings. A high quality photochromic tint film helps to control the amount of light/ultraviolet radiation in a room.

Photochromic tint film

The photochromic tint film is a thin material you can install on a window surface. You can use this film on polycarbonate or glass surface that do not have photochromic properties.


A photochromic film manufactured from polyester. Image source – SkyCool

A photochromic tint film is quite different from the traditional tinted films. As I had mentioned earlier when discussing various applications of photochromic technology, these films change the degree of tint depending on the light intensity. An increase in the sun’s UV radiation or brightness makes the film darker and vice versa.

This is quite essential for architectural works within the equatorial regions or when the weather is quite unpredictable. It will help you control light intensity and harmful ultraviolet radiations.

Remember, it is this light intensity or ultraviolet radiations that cause an increase in temperature within an enclosed structure. With a photochromic tint film, you’ll reduce the expenses associated with air conditioning. You don’t have to use fans to cool the room. The blocking excess sun’s energy automatically results in a cooling effect.

The photochromic tint film is popularly used in the building and construction industry alongside other technologies such as electrochromatic, photovoltaic, day lighting, etc.

In the recent past, photochromic tint film manufacturers have embarked on R&D to improve performance and reliability. This follows claims that photochromic technology tends to cause a cooling effect as it blocks the sun’s energy, which could warm an enclosed area. Such situations require the use of heaters to warm the enclosed areas and this may increase energy expenses.

Therefore, you need to purchase window tint film with the right photochromic molecules. You’ll only achieve this by purchasing the photochromic tint film from reputable manufacturers and suppliers. Next, I will discuss a few photochromic film manufacturers you may consider.

Photochromic film manufacturers and suppliers

In case you’re looking for a high quality photochromic film, you need to contact a reputable manufacturer and supplier. You should go for reputable photochromic brands or manufacturers that focus on quality control.

Some of the most popular photochromic film manufacturers and suppliers include:

Skycool photochromic films

Skycool is of the leading photochromic film brands in the market. The company serves automotive, residential and commercial industries. The company has invested in its brand products such as Huper Optik, Solar Gard, Armorcoat, etc.

Jetpower Photoelectric Material Co. Ltd.

Jetpower Photoelectric Material Co. Ltd. is one of the leading photochromic film manufacturer. The company is based in China and it produces a wide range of photochromic films with varying tints such as gray, brown, purple and yellow.

Chameleon

Chameleon is one of the leading photochromic smart window film brands. The company aims to transform the market by providing high quality and reliable films for the following industries: automotive, architectural, residential and commercial buildings.

Carestream Contract Manufacturing

Carestream is one of the leading manufacturer and supplier of smart films. The main products include photochromic film, electrochromic film, thermochromic film, etc.

Sentuitive

This is a leading photochromic film brand. The company supplies a wide range of self-tinting glass for both commercial and residential building.

Saharax

Saharax is yet, another company that specializes in photochromic tint films for the automotive industry.

Other companies that have invested in this industry include Absolute Tint and Garware Polyester Ltd., 3M, etc. Here is a Global Photochromic Films Market Research Report 2016. You’ll get a comprehensive list of all photochromic film manufacturers and suppliers.

In the previous section, I mentioned photochromic film applications in the automotive industry. For sure, automotive industry has benefited from this technological advancement. Take for instance, the vehicles windscreen/windshield and window; they are designed with various types of films to enhance performance. That is, to improve vision, eliminate glare, resist scratches, etc.

3.7 Photochromic Windshield

A number of vehicles have windshields that automatically react to the ultraviolet radiation. They tint during the day and turn clear at night. The working principle is not different from that of the photochromic goggles, sunglasses and lenses that I had discussed in the previous chapters.


A BMW windshield with a photochromic film.

You should note that this technology is quite different from the low-cost LCD technology where users can opt to darken the windshield depending on their desired settings.

Still, the photochromic windshield is a better option compared to the low cost LCD technology. Photochromic process does not require human intervention – it’s automatic. You can learn more about window films here.

Normally, the photochromic film for windshields should be applied on the outer surface. Moreover, other additives are added to ensure the surface is scratch resistant.

Remember, wipers may cause unnecessary scratches that may impair vision. Furthermore, the windshield should be polarized to reduce glare. Remember, the directional light from the oncoming vehicles may cause glare that could make it impossible for the driver to see clearly.

With these in mind, I will now discuss two common examples:

Photochromic tint for cars

Photochromic tint for cars have completely revolutionized driving experience. As a driver, you’ll not suffer from the sun’s bright light and ultraviolet radiation. The photochromic tint will automatically change its color to provide the required level of tint.

Below is a video that clearly illustrates what happens to windshields with photochromic tint films.

Photochromic glass for cars

The working principle for photochromic glass for cars is the same as that of the tint films and safety goggles or shields. They will protect you from the harmful ultraviolet radiations.

Clearly, photochromic is a versatile technology that you can use in any application where the intensity of ultraviolet radiation should be regulated. They tint and clear automatically, thus, very convenient.

Lastly, let’s review yet, another key application of the photochromic technology. This is the photochromic safety glasses.

3.8 Photochromic Safety Glasses

Photochromic safety glasses are important safety accessories we need when outdoors. At times, the ultraviolet radiation may be too much that you can hardly see. This is where photochromic safety glasses become handy.

You can classify photochromic safety glasses based on very many factors such as applications, type of material, type of coating, etc.

Here, I will focus on the following types of photochromic safety glasses: polarized photochromic safety glasses, general purpose photochromic safety glasses and photochromic prescription safety glasses.

Polarized photochromic safety glasses

The working principle of polarized photochromic safety goggles is the same as that of polarized photochromic sunglasses I had discussed earlier in this chapter. The good thing about these safety glasses is that they have two essential treatments – photochromic and polarized surface.

I will use two simple explanations to help you understand why I recommend polarized photochromic safety glasses for the most demanding applications.


A polarized photochromic safety glasses. Image source – Wikipedia

First, let me begin with the photochromic molecules in these safety glasses. Basically, these are considered ultraviolet reactive safety glasses. They respond to the ultraviolet radiation by tinting or darkening. In the absence of ultraviolet radiation, the lenses lighten or retain their original color.

With the polarized photochromic safety glasses, you’ll be 100% protected from the harmful ultraviolet radiations. Moreover, you don’t have to carry extra safety glasses.
Secondly, the polarized safety glasses will eliminate any instances of glare. In case you’re that person who participates in outdoor activities such as fishing, snowboarding or boating; you should have polarized photochromic safety glasses.

Glare and ultraviolet radiation will cause eye muscles to strain. This is because the eye muscles will be adjusting to accommodate the varying UV radiation and glare. In the long run, you may end up developing serious eye problems or get involved in an accident.

Again, you should be warned that not all polarized photochromic safety glasses available in the market meet the recommended quality standards. You may end up buying photochromic polarized safety glasses that do not meet the ANSI Z87.1-2015 criteria.

In short, go only for the reputable brands. Such safety glasses are subjected to strict quality inspection.

General purpose photochromic safety glasses

I know many people shy away from photochromic safety glasses with the assumption that they are very expensive. This is not the case. There are the general purpose photochromic safety glasses that are designed for normal outdoor activities.

The general purpose photochromic safety glasses will protect your eyes from the sun’s harmful radiations creating a conducive environment for you to go about the daily routines. You don’t have to change safety glasses when going outdoors.

You can use the same safety glasses both when indoors and outdoors. They will automatically adapt to the changing light conditions. They will darken on exposure to ultraviolet light and return to the original color in the absence of UV light.

Other general purpose photochromic safety glasses have polarized surfaces. This eliminates glare that could impair vision. Other coatings may include anti-fog, anti-finger print and anti-scratch coating.

But, what brings the difference between the general purpose and other photochromic safety glasses?

The difference between the two depends on the grade and amount of photochromic molecules embedded on the safety glass surface. A high grade photochromic molecules will react faster than low grade.

It is for this reason that you have to specify the nature of the application for which, you intend to use the safety glass for. For example, a photochromic reading safety glass is quite different from photochromic skiing safety glasses. This is quite clear when you look at both the design and structure.


Reading glasses. Image source. Image source – Safety Glasses U.S.A.

Photochromic skiing goggles. Image source – The Independent.

Definitely, you’ll find that another distinguishing factor between the two photochromic safety glasses is the cost. The general purpose safety glasses are cheaper.

Our last product in this list is:

Photochromic prescription safety glasses

Do you need prescription glasses? Well, this is the first accessory you should buy to protect your eyes from the harmful ultraviolet radiation or bright light from the sun.

The available photochromic prescription safety glasses are designed for maximum visual clarity. They guarantee safety all times even in the most hostile weather conditions.


Oakley safety glasses. Image source – Oakley Ray Ban.

All photochromic prescription safety glasses filter all harmful ultraviolet radiation and allow only a sufficient amount of light to reach the eye. Also, these safety glasses feature other coatings that improve performance and reliability. That is, the safety glasses are designed with a permanent anti-fog, anti-scratch and iridium coating. Ideally, these glasses are safe and offer maximum protection.

At this point, I am sure you’re well conversant with all the vital aspects of a photochromic technology. More importantly, I’ve also explored all the possible applications of photochromic technology. So, as you shop for a safe and reliable photochromic equipment, ensure you remember all that you’ve learnt from in this photochromic eBook.

However, before I conclude, it is important to review a photochromic safety equipment buying guide:

3.9 Photochromic safety equipment buying guide

You must have learnt about the key aspects you need to consider when buying any photochromic safety equipment. This section will act as a quick reminder that will help you to make the right decision faster. Here are the key aspects you should consider:

  • Consider material for the lens – I recommend polycarbonate
  • Check quality and safety standards – must conform to the ANSI Z87.1
  • Where do you intend to use the safety accessory?
  • Evaluate types of coating/surface treatment – photochromic, anti-fog, anti-scratch polarized surface
  • Go for reputable and established brands
  • Compare prices
  • Search for product reviews online

With these, I am sure you should get appropriate equipment that meet your specific needs.

Again, I’d also wish to hear from you. Did you take any short notes as you read this photochromic eBook? Do you need any clarifications on issues related to photochromic technology?

You can send me an email and I will assist you.

Conclusion

Safety is a major concern in any outdoor activity and over 76% of eye problems are associated with exposure to ultraviolet radiations/bright light. As you can see from this photochromic eBook, you can easily stay safe by using safety equipment with photochromic molecules. They will automatically tint on exposure to UV radiation, saving you from any eye problems and unnecessary expenses.

I am sure no one wishes to develop eye problem so, take precaution by purchasing photochromic safety equipment. Remember, prevention is better than cure and this is a sure way to stay safe.

Reference:

  1. Wiki page for photochromic lens
  2. Photochromic Material May Help Next Generation Of Energy-Efficient windows
  3. PHOTOCHROMIC SUNGLASSES
  4. How Transitions® lenses filter harmful blue light
  5. Photochromic lens innovations fuel consumer demand
  6. Photochromism- Fundamentals and Applications (PDF)
  7. Photochromic dynamics of ophthalmic lenses
  8. Infographic: 11 Great Technologies to Skyrocket Your Football Visor Business