Screen Printing on Polycarbonate: The Ultimate Guide

What is Screen Printing?

Screen printing (also known as serigraphy or silkscreen printing) is a printing method that needs three key equipment:

• Squeegee
• Screen
• Ink

In this procedure, you can print a desired design on material by forcing the ink through a stencil or mesh.

Either by an impermeable substance or cutouts, the ink spreads to surfaces that the screen allows.

Through this, you can place various designs on the material – think for instance customized t-shirts.

Screen printing became globally popular in the 18^th century, and it was mainly for decorating walls, clothing, and other objects.

A century later, its popularity in the world of advertising grew.

In the 20^th century, screen printing went mainstream by Andy Warhol’s work who employed this technique to produce his art.

Art of screen printing

Presently,there are both manual an automatic types of screen printing.

And, the printing technique is more famous than ever because of its versatility and capability to reproduce durable, crisp images and vibrant colors.

Benefits of Screen Printing on Polycarbonates

Screen printing on polycarbonates is advancing and flourishing in the 21st Century, consistently stretching to new markets and uses.

It is because, screen printing on polycarbonates demonstrates its unrivaled flexibility among industrial and commercial printing operations.

Screen printed name plates – Photo courtesy: SCREEN CRAFT

Blending the topmost image quality with accuracy engineering and monitoring, you can use current screen printing machine for a broader variety of polycarbonate materials.

It is better than other printing technologies.

Screen printing’s versatility and cost-effectiveness, specifically in manufacturing setups, guarantee it continued use regardless of some progresses in digital printing.

From limited-edition decorative screen printing to mass industrial image replication.

The numerous intrinsic advantages of screen printing on polycarbonates signify fresh opportunities for advancement and continued supremacy within the printing sector.

If you are a commercial printer working on balancing quality and cost considerations, screen printing offers you substantial benefits.

Obviously, this will be in four essential areas, i.e.,profitability, versatility, quality, and durability.

· Quality

Screen printing on polycarbonates delivers quality.

Current screen printing machines offer you with a superior color saturation and wider color palette.

Thicker ink application to the polycarbonate material signifies more pigments than digital printing, leading to richer, more sparkling colors.

Serigraphy also enables the introduction of special effects and custom colors into the process of printing on polycarbonates.

· Durability

Silkscreen printing on polycarbonates provides durability.

Thicker coverage of ink in the printing operation leads to a longer lasting image than with digital printing.

You can introduce coatings and additives to ink to boost resistance to moisture, UV rays, scratching, and chemicals to enable, without wearing or fading, outdoor and extreme environments usage of screen-printed polycarbonates.

· Versatility

Screen printingprovides versatility.

You can screen print on a broader variety of polycarbonate materials compared to digital printing, including polycarbonate sheets and films.

You also have a wide range of inks to choose from including unique specialty inks.

Screen printing on polycarbonates is the best option for most of mass graphic print creation.

· Profitability

Screen printing spurs profitability. Due to the reliability and stability of the printing process, screen printing is the best choice for high-volume and long manufacturing runs.

Additionally, the consistency of the verified technology makes this printing on polycarbonates process more economical than digital printing.

In addition to its substrate, color palette, and size restrictions may need often costly equipment and software updates.

Polycarbonate overlay – Photo courtesy: SCREEN CRAFT

Frankly, these benefits combine to give a satisfying reason in support of screen printing on polycarbonates where image quality and uniformity are crucial.

Step-by-step Process of Screen Printing on Polycarbonate

To commence screen printing on polycarbonate materials, get the equipment needed;

• Sensitizer and photo emulsion
• Squeegee
• 250 W bulb
• Screen
• Printing surface
• Frame
• Small piece of cardboard

You should carry out all the procedures outlined below in black or pitch dark room.

Printing on polycarbonate sheet

Step 1:

First, create a design or image.

It is this image that you will print on the polycarbonate surface.

You can either draw or apply photoshop to sketch the image.

Make sure that the design is in black or other dark color since the role of the image is to obstruct the light.

Step 2:

After designing it, print the image utilizing a laser jet printer on a transparent sheet.

In the right proportion, mix the emulsion and the sensitizer, then pour the blend on the screen.

Spread the mixture throughout the screen using a squeegee while ensuring that the surface you are smearing the emulsion blend is bigger than the area of the image.

Step 3:

With the screen face down, set down the screen and frame made of black cardboard.

Place the clear sheet with the printed design over the screen.

Using a tape, attach the sheet to the screen and frame.

Put the lamp near the sheet, with the distance between the two not exceeding one to two inches.

Let the layout undisturbed for approximately 15-20 minutes.

Step 4:

You will notice fine blue lines at the point the image is burned or imprinted in the screen.

If you are not satisfied with the image look, allow it to expose for an extra 10 minutes.

Make sure that you do not let it expose for too long since overexposure may cause the image to bleed.

Step 5:

Sprinkle cold water on the screen till the part where the image burned begins to flake off,and you are capable of observe through the screen.

Ensure that the image section on the screen is transparent.

Allow the screen to dry for a few minutes.

After drying of the screen, using a tape, cover the section of the screen without photo emulsion.

Make sure to cover all areas except the photo emulsion and the image.

Step 6:

It is turn to print now. Place down the polycarbonate sheet or film you want to print and put a square piece of cardboard below it.

Set the screen over the polycarbonate material and pour small quantity of the chosen ink throughout the screen top horizontally.

Step 7:

With the squeegee, begin smearing the ink while moving the squeegee up and down as you put pressure on the screen.

If it is your first attempt on screen printing on polycarbonate sheet or film, experiment with a waste paper prior to the actual printing.

Repeat this procedure twice or thrice till you feel that you have engraved the ink on the polycarbonate surface.

Step 8:

Allow the polycarbonate sheet or film to dry up for a few minutes and then wash and cleanse the ink from the screen in order to utilize it to print another image.

Polycarbonate signs

How to Choose the Best on Screen Printing Machine

Regardless of the type of screen printing machine you own, there is some fundamental equipment that you will need.

The screen or stencil is of prime essence because it dictates the image and design outcome.

It is made up of the frame, the mesh, and the photosensitive medium where you create the image.

The Squeegee is the rubber clutched in a firm handle.

The substrate is the surface you are to print the design on, in your case the polycarbonate sheet or film.

The machine base holds the substrate in position and enables the screen to print on it.

It is always the base of the whole screen printing machine.

Let’s have a look at some tips that will assist you choose the best screen printing machine for your application

Section of screen printer

Manual or Automatic Press?

Simply put, what quantity of polycarbonate are you intending to print?

Intention is essential.

In case you are planning to do the printing by yourself, launch a small brand, or you just enjoy the action of pushing and pulling a squeegee.

Manual screen printing machine

Then a manual screen printing machine is sufficient for your desires.

Manual screen printing press is the common starting point for majority of beginning printers and small-scale screen printing businesses.

I advise beginning with extensive research when delving into it.

High standard manual machines are a venture that grows with you.

Selecting a high-quality manual screen printing machine to start with will last you long during any growth your business may experience.

You can always improve to an automatic press in the future.

However, if you are truly serious over beginning a polycarbonate screen printing venture, you may go straight and purchase an automatic screen printing machine

Tabletop or Free-standing Press?

Here, the concern is mainly on space.

Will you be printing out of spare room or kitchen?

Is how to screen print within minimal space a factor you’ve thought?

If that’s the case, you might consider investing in a tabletop screen printing machine.

Table top screen printing machine

Sincerely, inadequate space should hinder you from realizing your desires.

There are numerous exceptional tabletop screen printing presses on the market that can achieve same results just like free-standing screen printing press.

There are advantages to being small, but if you’ve enough space to expand, then get the full-sized screen printing machine.

These printing machines are long lasting,and you will commonly find them in any manual screen printing premise.

The benefit of going big is longevity in the long run.

If you’re intending to operate the machine for 8 hours per day, or do mass screen printing, then you will need a press that can function for decades.

Select a screen printing machine brand with good track record.

Ensure that whichever press you acquire, it is a pleasure for you to work on since you will be spending most of your time printing with it.

How many Stations and Colors?

Deciding on the number of stations and colors may be the most difficult part of when choosing a screen printing machine.

The more stations and colors you can work with, the more you are capable of doing, and the more expensive it becomes.

How many colors would you want to print per design? 

The aggregate of colors you employ in your design ought to equal the amount of print heads on your press.

This is due to the fact that each head is capable of holding only a single color at a time.

Even though there are solutions around this, they consume much time and less precise.

If you are intending to print CMYK (Cyan, Magenta, Yellow Black), you will require a minimum of 4 colors.

But, if you plan to only print a single color designs like block text, then one or two color screen printing machine is fine with you.

Majority of production printers select between a 4 and eight color silkscreen printing machine.

These presses enables you to print flexible designs and even perform more than one screen printing on polycarbonate task at the same time on the printing machine.

This is very instrumental for those rush tasks, or if you have several deadlines.

You will need to add multiple stations as well if you decide to select a screen printing press with numerous colors.

The number of stations to select when deciding what serigraphy machine to purchase depends on the volume of work and material you print on.

Every extra station you have enables you to finish a full print on several polycarbonate sheets or films at a go.

Therefore, it really depends on your preference. If you want to create four color designs, buy at least a 4 color 2 station screen printing machine.

If you desire quicker printing and reduced waiting, add extra stations to your machine.

Besides, you can purchase a 6 color 4 station screen printing press.

Top press 4 color screen printing machine – Photo courtesy: Screen Printing Supply

Alternatively, you can modify it to an 8 color 6 station screen printing press for a really adaptable and powerful silkscreen printing machine.

When looking at the arrangement, you would you screen printing machine to possess, seriously factor in your requirements and aspirations.

Venture into it ready to put your money in what you need the first time, or undertake that you may have to change into a bigger machine in future.

Remember, it’s completely alright to begin small and extend later.

Most business involved in screen printing begin with simple single color screen printing machine and expand in future.

When you buy high-quality machine,to begin with, it will be really difficult to get rid of it.

Majority of big stores still own the early small printing machines the commenced with since you will often have small jobs.

Screen Printing vs. Digital Printing on Polycarbonate

For the past twenty years, the world has encountered a tremendous technological advancement.

Things considered impractical back then are currently barely accorded attention as we undertake our daily lives.

The printing sector is no exception.

With technological advancement, printing companies have moved from the customary silk screen printing method into a generation based largely around digital devices.

This transition from one technique to another begs the question, “what are the dissimilarities between screen printing and digital printing?”

For the fellows inexperienced in the printing industry, digital printing employs 4 color processing (CYMK) to produce a design and replicate it by forwarding it straight to the printing machine.

Conversely, screen printing utilizes silk screens to produce a design and replicate it layer by layer through printing one color at a time.

Still the query remains, “Which technique is the better option, and why?”

Digital printer

In summary, when set side by side every technique possesses its merits as well as demerits.

It is difficult to conclusively say as a matter of fact, as at the moment both techniques are extensively in application; neither technique is exiting the scene for a long time to come.

Properties of Digital Printing Polycarbonate

• Employs4 color processing to produce design (CMYK)
• Does not need screens or plates
• Utmost print size is 120″ x ∞

Advantages of Digital Printing Polycarbonate

• Completes printing of all colors in one pass
• Registration between colors is exemplary
• No bleeds or traps since it uses butt registration
• Able to duplicate any graphics type
• Minimal pre-press preparation

Why Choose Digital Printing Polycarbonate?

• Reduced cost in low to medium volume runs
• Briefer lead times because of reduction in setup. Design goes direct to press from the computer, no plates.
• The process printing standard is superior to that of screen printing press. Dots per square inch (DPI) is higher resulting to better resolution.

Properties of Screen Printing Polycarbonate

• You lay down the colors one by one in layers so as to develop a finished product.
• Utilizes a different silk screen for every color printed
• Utmost print size is 32″ x 45″

Advantages of Screen Printing Polycarbonate

• You are able to match any color since the ink is custom blended for every task.
• Inks possess higher opacity compared to digital system.
• Reduced cost of inks.
• Able to print reverse colors exceptionally well.

Why choose Screen Printing Polycarbonate

1. Reduced cost for mass production tasks.
2. Placesheavier, rich colors on reverse frameworks.

FAQs on Screen Printing Polycarbonate

I know you could be having some questions on screen printing on polycarbonate sheets.

That’s why I have this section for you – I want you to be an expert in screen printing on polycarbonate sheet.

Polycarbonate overlay printing

1. How long will my screens last for screen printing?

If you take good care of your screens, they can last for a very long time.

This is particularly possible with retensionable screens.

You can tighten as required the mesh on retensionable screens, making them appear “new” again.

Tough frame screens (aluminum and wooden frames) can as well endure for a lifetime if you take a few simple care of them.

2. What is the appropriate space of “Off-contact” for screen printing?

“Off-contact,” for the individuals unfamiliar with the term, is the space between the polycarbonate substrate and the bottom of the screen.

Its role is to boost printability during the process of screen printing.

When screen printing polycarbonate sheet or film, the “thickness of a dime” is an appropriate point to start for the off-contact space as you increase and decrease as required.

The objective of off-contact screen printing on polycarbonate materials is to get a good “snap-off” as the squeegee crosses over the screen, leading to a sharp printed image.

3. How many colors can I print?

All manual screen printing are similar – a single color for each screen unless you put several colors on one squeegee during printing so as to obtain a rainbow effect.

This is because of the ink structure, the ink you use bleed together making the colors mix during printing.

To maintain the colors separate, always use different screen for every color.

Nonetheless, based on your design, you can in some instances use one screen for printing several colors.

You can achieve this by covering the bottom of the screen behind the surface where you do not want the ink to get into contact.

Print all your polycarbonate materials and then reverse the procedure for other colors.

This is effective though only in short runs since the ink will start to soak through the material covering the screen.

It will thus require you to replace or the polycarbonate material below will get marked.

4. Can I utilize fabric ink on polycarbonate?

No, you ought to use a specialized plastic ink, or the print will fail to dry or scratch off.

Polycarbonate sheet screen printing – Photo courtesy: ADHESAPLATE

When screen printing on polycarbonate and other non-absorbent substrates, the ink fuses and cures itself to the substrate, as a result becoming part of the material.

5. How does UV ink work?

As the name indicates, UV inks cure under UV light.

Molecules and molecular complexes (monomers and oligomers) make up the ink and determine its physical characteristics.

Performance additives and pigments also make part of the inks’ ingredients coupled with q photo initiator.

Which, when subject to UV light, delivers free radicals that causes the bonding of the monomers and the oligomers, leading to a solid ink image.

The ink, in essence, sits on top of the polycarbonate material, instead of settling in, making it perfect for smooth surface printing such as screen printing on polycarbonates.

6. What are the disadvantages of UV screen printing on polycarbonate?

In comparison to other printing methods, UV screen printing does not have major challenges.

The main shortcoming is dependent on the very feature of screen printing.

The element that there should always exist excellent adherence between the polycarbonate substrate and the screen, while the former should always be flat.

This implies that UV screen printing is not the right choice for materials with complex shapes.

7. How long will my unexposed screens last?

Unexposed, coated screens ought to be “exposure ready” for a duration of6 months.

This is possible if you store them in airtight vessel which, prevents them from being exposed to humidity and light.

It will be very difficult to expose screens that you have stored for too long.

You will need to reclaim and re-coat them with emulsion.

8. How do I avert under cured emulsion?

After coating your screens with emulsion, give the emulsion sufficient time to completely dry; a duration of 12 hours is normally adequate.

To promote proper drying, dry the screens you’ve just coated in a warm, dark room.

You can as well use screen drying cabinets to quicken the drying process.

Most screen printing tools suppliers stock these cabinets.

After exposing a screen and washing out the stencil, let the screen dry for a minimum of an hour before performing another printing.

You can run a fan over the screen to fasten the drying process.

Post exposing a freshly-imaged screen on the exposure component will stiffen the emulsion and boost its durability.

9. How do I clean my screens?

You can either cleanse your screens down wholly which is commonly necessary after 150 prints.

Though it depends with the type of ink you are using, or when you observe a problem while printing.

Screen printer

Cleaning in the process of printing

Wash all the ink from the squeegee and carry out a blank print onto a waste paper in order to completely remove the ink from the screen.

Using a very damp fabric, clean the back of the screen softly ensuring not to scrape off the film.

You will observe water beginning to disintegrate the ink in the screen.

Redo the procedure with a different piece of cloth if necessary then pat dry.

Ensure to carry out a test print using a waste paper as the water comes off, and continue testing till clear.

Cleaning when finished printing

Wash all the ink from the squeegee and carry out a blank print onto a scrap paper, in order to remove the ink completely out of the screen.

Run cold water over the screen till the ink begins to disappear. You can rub your finger on the screen to aid remove the ink equally.

10. Why does polycarbonate film turn yellowish when I screen print using UV inks?

Polycarbonate is reactive to UV wavelengths below 320 nanometers.

Disintegration of the molecular bonds due to photo-oxidation causes the surface yellowing.

The molecular bonds absorb UV energy generating radicals.

Consequently, a reaction takes place between the atmospheric oxygen and the radicals, which leads to the physical and appearance change within the polycarbonate.

11. How can I avoid or eliminate the yellowing on polycarbonate surface?

If you use UV screen printing on polycarbonate, you can only minimize the yellowing but not completely avoid it.

Using additive curing unit bulbs like gallium and iron is a proven means of reducing the yellowing.

These bulbs release reduced UV energy in the shorter wavelengths harmful to polycarbonate.

Additionally, curing every ink color appropriately to reduce exposure of the polycarbonate to UV energy.

Ensuring proper maintenance of the curing unit will come in handy in minimizing degradation of polycarbonate material surface.

12. What is the number of lamps that I require for curing?

Dependent on the ink type and the substrate you want to screen print, a one lamp curing set-up may be adequate.

Nevertheless, if your budget permits, a two-lamp curing set-up will offer the advantage of a quicker cure.

More particularly with slower-curing pigments, and it will encourage speedy general rates of production.

Two lamps are often better off than single since a two-lamp set-up offers more total energy at similar lamp settings and conveyor speed.

The key factor you should take into consideration is if the curing unit will be effective enough to cure the inks on the polycarbonate surface at reasonable fabrication speeds.

13. How do plasticizers affect ink adhesion on PVC?

Plasticizers are chemicals that you add to plastic when processing to make the final product soft and flexible.

The amount and type of plasticizer added to any plastic substance is dependent on the thermal, mechanical, and electrical features you expect from the plastic.

Plasticizers incline to move to the surface of the polycarbonate and impact adhesion of ink.

Plasticizers on the surface act as contaminants that possess the capability of lowering the surface energy of the polycarbonate surface.

More contamination lowers the surface energy,and this increases the chance of poor ink adhesion.

You can clean polycarbonate material affected by this problem using a mild solvent prior to production to boost their printability.

14. How does flame treatment on polycarbonate work?

Plastics are naturally non-polar and have basically inert surfaces, meaning low surface energy.

Flame treatment is among the many techniques of pre-treating plastic materials so as to boost the surface dyne level.

The technique commonly find application in bottle-printing industry though it also helps in film-converting and automotive industries.

Apart from boosting the surface energy of plastics, flame treatment as well assists in eradicating surface contamination.

During the process of flame treatment, the high temperature initiates alterations on the polycarbonate surface through oxidation and disintegration of hydrocarbons to release ions, radicals, and other charged particles.

This alters the polarity of the surface of the polycarbonate, which improves wettability and ink adhesion.

15. What influences the shelf life or stability of UV inks?

Ink storage is the key factor that affects the stability of UV inks.

The package of the ink is commonly plastic rather than metal since the former are permeable to oxygen.

In addition, an air gap is necessary between the container lid and the surface of the ink.

This air gap, particularly the oxygen component of the air, assists in reducing chance of any untimely cross-linking inside the ink.

Apart from packaging, the temperature at which you store the ink containers also performs a crucial role in retaining their stability.

High temperatures will result in reaction of the ink and its premature cross-linking.

Alterations done to the original formula of the ink may equally impact shelf stability if you store the remaining ink.

Additives, specifically photo initiators,and catalysts, may shorten the shelf life of UV inks.

Lastly, subjection to stray UV light from lighting and windows when you leave the ink container open may influence stability.

16. What is dyne level of a polycarbonate material?

Dyne per centimeter is measurement unit applied to quantify the size of force generated on a surface.

The intermolecular attraction of a specific solid (surface energy) or liquid (surface tension) causes the force.

This measurement is known as the dyne level.

The surface energy or dyne level of a polycarbonate material is an indication of its ink adhesion and wettability.

Dyne level is a physical characteristic of the material.

Majority of films and other substance utilized in the printing industry possess very low dyne levels.

Like polypropylene with 29 dynes/cm and polyethylene with 31 dynes/cm, and for this reason you should treat them.

Treatment, increases the dyne level of specific film, though momentarily.

Thus factors like dust, storage, contamination, amount and time from first treatment, handling, and humidity will impact the dyne level during screen printing on polycarbonate materials.

Because dyne levels adjust with time, it is necessary you treat or retreat your polycarbonate sheets or films immediately before screen printing on them.

17. Are UV inks rated green, and if that’s the case, why?

Compared to solvent-based inks, UV inks are green.

Since UV-curable inks are 100% solids, every component of the ink reacts into the eventual ink film.

On the other hand, when solvent-based inks are drying up, the solvents vaporize into the atmosphere.

Since the solvents are volatile organic compounds, they are not ecologically friendly.

Conclusion

In comparison to other plastic-like polythene, screen printing on polycarbonate sheets or films should be a walk in the park.

Polycarbonate possesses a naturally high dyne level, implying that you can obtain better ink adhesion.

Different from other plastic types, polycarbonate substrates need no pre-treatment of surface before screen printing on them.

And, because polycarbonate sustains higher curing temperature, the stability of these materials enables the printer to retain better registration.

Even though polycarbonate sheets and films possess a longer shelf life compared to other types of plastics, there can be alteration in ink adhesion as the material ages.

To prolong the shelf life of your screen printed polycarbonate material, you ought to keep then in humidity and temperature regulated environment.

At WeeTect, we have the capability to process polycarbonate products and parts to different finishes.

Talk to us today, and we will advise you on the best polycarbonate fabrication and finishing procedures.