"Green Printing" Uses Sustainable Methods and Materials

One of the world's foremost authorities on screen printing inks and techniques is up to his elbows in developing more eco-friendly decorating processes. Come along as Michael Beckman shares his wealth of knowledge on the green garment decorating trend.
Oct 1, 2007

By Michael Beckman, Contributing Writer

Most of us try to be aware of the environmental impact of the choices we make in our daily lives — and that extends to our professional lives as well. Who doesn't want to make a positive impact? It may be as simple as taking mass transit or as complex as tracking our carbon emissions and trying to live carbon-neutral. The point is that the environmental movement has become a mainstream, ongoing and important part of society and commerce.

Many companies worldwide also are making an effort to be aware of the ecological impact of their products, as well as their manufacturing methods and materials. This effort has become an increasingly important part of their business plans, as it can increase brand value and profit margin and, ultimately, could decrease production costs.

Screen printed T-shirts have doubled as billboards for pro-environmental sentiments as far back as the first Earth Day in 1970. Because T-shirts have been so closely associated with environmentally conscious lifestyle choices, it only makes sense that our customers look to us to lead this movement. Thus, our impact on the environment becomes especially important to our businesses. Not only do we want to make responsible ecological decisions because of our sense that it is the right thing to do, but we are learning that it will help our businesses to be more successful and profitable.

The market will increasingly demand that we make the effort to be more sustainable and will reward the companies that do it well. In addition, we will likely see more regulations put in place to ensure that all companies use more environmentally responsible manufacturing processes. We also are seeing consumer backlash against unsafe products and manufacturing practices, and heavily polluting industries. Like many other industries around the world, screen printers need to implement serious and ongoing "green" initiatives in our factories. Simply put, we should try to be leaders in the effort to use sustainable production methods and materials.

Sustainability is usually defined as the ability to provide for the needs of the world's population without damaging the ability of future generations to provide for themselves. Green, in this sense, could be defined as something produced with little environmental threat or harm by using sustainable practices. One simple but commonly accepted way to think about sustainability is to consider the following: How much material is taken from the Earth to make the product? How soon is it replaced naturally? How persistent is it or how long will it take to return to its original natural components?

Smart Screen Prep
If you plan to sustainably screen print T-shirts, the first consideration should be film output. There are numerous devices available, and each has a different impact on the environment.

A traditional imagesetter uses photographic film processed with chemicals. Although these imagesetters can produce film at very high resolutions, they are the least environmentally friendly output option available. There are now a number of high-quality, Postscript-capable inkjet printers on the market that will print directly onto a clear polyester material that replaces chemically processed film. Even though these units have lower resolution than a standard imagesetter, they work fine for creating screens to print garments.

As a general rule, we can only make use of a resolution that is twice the final line count of the halftones used in the art. Because these inkjet printers don't use chemicals to process film, they are an improvement ecologically.

The newest option available is an output device that prints the image directly onto the screen for exposure — direct-to-screen (DTS), also known as computer-to-screen (CTS). These perform similarly to top-quality inkjet devices and are arguably the most environmentally friendly option in that no film is needed. Therefore, film is not wasted, no chemicals are used for processing and there's no need to store or dispose of the film later. The emulsions used in making the screens usually depend on the type of ink that will be printed through the screen rather than any particular environmental concern.

We Ink You Can
The inks used in screen printing generate the most concern, but they also provide the most opportunity to use green processes and sustainable materials. Plastisol inks are generally considered the easiest and most versatile inks for printing apparel. They also are commonly considered the least "green" ink option available.

While there is some genuine debate about this, my opinion is that plastisol inks are probably the least sustainable ink system used. These inks are made with polyvinyl chloride (PVC) resins. This material is often considered objectionable to the sustainability movement because it is a heavily manufactured, non-natural material. PVC is persistent in the environment as it does not easily break down into natural components.

On the positive side, this is why plastisols are very durable and why plastisol prints will last much longer than the shirts on which they are printed.

Although the PVC used in inks form an extremely small percentage of the total amount of PVC manufactured, some environmental groups would like to see its use curtailed completely. The good news is that within the print shop itself, plastisol inks can be handled in a completely sustainable way. The ink has a very long shelf life and it can be re-used almost indefinitely — therefore generating very little waste.

The ink does not cure by evaporation like water-based ink or other solvent-based inks. A closed-loop filtration system can easily be used during screen cleanup to control any material entering the environment.


Figure 1. A textural high-density plastisol print

Additionally, standard plastisols are easy to use and have unique performance characteristics. Plastisols allow the creative garment decorator to produce spectacular prints and special effects that are difficult or impossible to duplicate with other materials. Figures 1, 2 and 3 demonstrate the versatility of plastisols. They can be used to create everything from densely textured designs (Figure 1) to very subtle, soft-hand prints (Figure 3). Plastisols also are easily used in variable opacities and can be mixed to match nearly any color that's specified for garment decoration.


Figure 2. Standard flat color plastisol print

However, standard plastisol inks do present other environmental concerns. In addition to PVC, most plastisols contain a small amount of chemicals called phthalates. Phthalates are a large family of colorless, oily, liquid chemicals generally used to make vinyl soft and flexible.


Figure 3. A soft-hand plastisol print

Although they do a good job of this, there are some concerns and regulations regarding these chemicals. While the actual dangers of the phthalates used in inks are being debated, the major plastisol ink companies now offer many of their products in non-phthalate versions.

These non-phthalate inks are not as easy to work with as standard plastisols, but it is possible to use them to accomplish most of the common printing techniques. They lack some of the softness and flexibility of their standard plastisol counterparts, which makes them slightly more difficult on the press. Nevertheless, while these inks still contain PVC resins, they can be a good compromise that satisfies concerned customers.

In addition to non-phthalate plastisols, there are some new acrylic-based screen printing inks that are sometimes referred to as non-PVC and non-phthalate plastisols. Why? Well, an acrylic-type resin replaces the PVC resins used in regular plastisol. Also, the plasticizer in acrylic inks is normally non–phthalate, making these inks an even more eco-friendly alternative. Most of these acrylic inks have a fairly reasonable shelf life and can be re-used like standard plastisols.

Acrylics do have some of the same performance characteristics as standard plastisols, though they can be a little more difficult to print with and don't cure the same way. It can be hard to get a soft-hand print with these inks. However, as with standard plastisols, the halftone and detail are very good. With some experience, acrylic inks can be successfully made into high-density designs. The finished prints lack the soft finish of a standard high-density plastisol print, but this may be an acceptable compromise to some customers.


Figure 4. A print made with non-PVC plastisol gel ink

Clear gels and clear gloss acrylic inks also are available. There are some performance drawbacks with these gels regarding stickiness and the amount of gloss but, again, they may provide an acceptable compromise. Figures 4, 5 and 6 show some of the prints that are possible with these inks.


Figure 5. A high-density print made with non-PVC plastisol ink

Acrylic inks are usually a little more costly than standard plastisols and are substantially more expensive than standard water-based inks. As far as opacity, printability and ability to hold fine detail, they work well. Depending upon the type of printing you need to do, they can be a good alternative with regard to any green printing initiative.


Figure 6. A detailed non-PVC print

Just Add Water
An entirely different approach is to use water-based inks. There are many types of water-based inks available and each has very different performance characteristics. Some are very eco-friendly and can be used as part of a highly sustainable printing process. There are, however, some performance limitations with all water-based systems — so you have advantages and disadvantages.

There have been substantial improvements in water-based printing technology, but it's still not possible to duplicate all the varying looks a good printer can achieve with traditional plastisol inks. There are very few water-based specialty inks, with the exception of puff, reflective and some jewel-tone inks. Also, there are no water-based inks that can do high-density or gel prints, and that will likely remain impossible with water-based inks for the foreseeable future.

Unlike all the plastisol inks we have discussed, water-based inks cure as water evaporates out of the ink. This means that the water — along with whatever in the ink evaporates with the water — enters the environment. That's why proper shop ventilation is critical when using water-based inks. It also means the curing time is longer and more difficult to control.

Finally, all water-based inks can start to dry out during use, and overall shelf life is limited. This can make printing more difficult and, depending upon the type of water base, can limit the mesh count you can use and, therefore, the detail you can achieve in a print. The limitations of water-based inks are most apparent with "traditional" water-based inks.

These inks are inexpensive and easy to manufacture. In fact, with some experience and the proper equipment, printers can make them in small batches from basic natural components. These standard water-based inks have a very soft hand but little opacity and are generally used only to print light-colored shirts. They have a very limited shelf life and are difficult to re-use, so they generate more wasted ink than regular plastisols or more complex, manufactured water-based inks. While this type of water-based ink is considered a very green alternative, this extra waste is something to consider.

Watering the Dark Side
Of course, these thin, water-based inks cannot print on dark shirts. An eco-friendly alternative for printing darks is water-based discharge ink. This type of ink is very similar to traditional water-based ink, except that a chemical is added to the ink to remove dye from the garment being printed. The chemical will bond with the dye and evaporate with the water during curing. This will work properly only on garments made with fabric colored with a dischargeable dye.


Figure 7. A classic discharge print done with water-based inks

Using this chemical limits how eco-friendly we can consider this type of printing. Some of the chemicals that can be used for this are not as problematic as others, but adding any chemical for the purpose of discharging the garment dye affects the eco-friendliness of these inks to some degree. In addition, once the chemical has been added to the ink, the shelf life decreases substantially. These inks generally require disposal after just 24 hours. Color matching also can be very difficult with discharge inks.


Figure 8. A discharge underprint after flashing

To prevent some of these issues, you can use a discharge ink as an under print and then print colors on top using non-discharge water-based inks. This limits the waste and chemical usage to only one color. Figures 7, 8 and 9 show prints done with this method. The hand of a discharge/overprint is still very soft and the opacity of the print is improved. Exact color matching still can be difficult, but it is much improved over printing multiple discharge colors. However, the flash time for water-based inks — including discharge — is longer than for plastisol inks, slowing production times.


Figure 9. Water-based colors printed on top of a discharge underprint

H2O Advancements
There have been some major improvements in manufactured water-based inks in recent years. These newer inks have a number of performance advantages over the basic water-based inks discussed above and are as potentially eco-friendly and sustainable as any alternative.

Much like traditional plastisol, these water-based inks are sold ready to use as colors or underbases and have a thicker viscosity that yields greater opacity on finished prints. They can be reduced with water and other modifiers for a softer hand.

These new water-based ink systems resist drying, and remain useable far longer than traditional water-based and discharge inks. They can be re-constituted with water — and additional binder, if needed — which can cut back on waste. Shelf life of these newer water-based inks is substantially longer as well because the manufacturers have developed technology to encapsulate the water in the ink in such a way that it does not readily evaporate until printed.

Taken together, the properties of this new generation of water-based inks can be used to print greater detail and finer halftones through higher mesh screens. Unlike traditional water-based inks, the opacity of these new inks allows them to successfully print on dark garments, typically on a white underbase just as you would do with standard plastisol inks.

In short, the performance characteristics of these new water-based inks allow them to reproduce many of the same types of prints as plastisol.


Figure 10. This print was done with a new generation of water-based ink, modified extensively to maintain opacity and achieve a soft hand.

The print in Figures 10, 11 and 12 was done entirely with water-based inks that were modified extensively for a balance of soft hand and opacity. All of the colors, including the white underbase, were printed with 355 lines per inch (lpi) screens. Because the under print was halftone art printed with such fine mesh count, it flashed as quickly as standard plastisol.


Figure 11. All colors, including a white underbase, are water-based inks printed with 355 lpi screens.

By carefully adjusting viscosity of the colors — and, therefore, opacity — bright prints with excellent color matches are possible even on dark shirts. This new group of water-based inks is probably the most eco-friendly printing option on the market. They are an obvious choice for any printer making an effort to use sustainable materials and methods.


Figure 12. Carefully adjusting the viscosity of these new water-based inks produces bright prints and good color matches, even on dark shirts.

On the down side, cost of these inks is generally much higher than traditional water-based inks. Even with the better performance and in spite of the higher price, special effect prints — such as high-density and gel effects — are not possible with these inks.

There also are many other compromises you have to make when using these new inks. The soft hand and the opacity need to be balanced, especially when accurate color matches are needed on dark garments. It requires a great deal of practice and experience to modify and use these new water-based inks to achieve all the different looks needed by most customers.

Having said all that, I think it is definitely worth the effort to become adept with these different types of printing materials to become as eco-responsible a printer as possible. In addition to film, inks and printing methods, there are numerous other aspects to any successful green initiative. The clean-up and screen reclaiming areas in most screen printing factories are an obvious and important place to look for ways to improve ecological impact. Better and more complete filtration systems, newer technologies, cleaner and less damaging chemicals, and water usage limitations are all ways to make a factory more eco-friendly.

Take a careful look around your shop and you'll see many obvious ways to become more sustainable. For example, a roll-on, water-based adhesive for the printing platens can replace aerosols. Use less water throughout the shop and you can employ more environmentally friendly clean-up solvents and materials. Finally, monitoring and regularly cleaning the dryers can save energy.

We should all regularly evaluate every aspect of our production to see how we can become more responsible printers. This is the best way for us to continually upgrade to the most sustainable methods and materials available.

Michael Beckman is the research and development manager for European T-Shirt Factory (ETF), Istanbul, Turkey. Beckman pioneered the development and use of many specialty ink formulations and applications. Based in the United States, Beckman helps guide the impressive output and award-winning designs of ETF, one of Europe's largest contract screen printers. He can be reached at mbsp@comcast.net.

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