SCREEN PRINTING ON STRETCHY SUBSTRATES

Athleisurewear is more than a trend, it has become a lifestyle, with substrates that are made of lightweight, soft and stretchy fabrics. A great example of this is our new Ladies’ Modal Stretch styles, which are made of a modal/polyester/spandex jersey blend that has a super-soft and flowy feel. Like most blended garments there are several things to consider before attempting to decorate these types of garments. Below, I’ve outlined a few tips, types of useful inks and additives, along with a simple print spec sheet to better help you achieve success when screen printing stretchy substrates.

KNOW YOUR SUBSTRATE

First, understanding the fabric content is vital in helping to determine the best print methods. Do your homework and get familiar with the makeup of Polyester, Spandex, Lycra and Nylon combinations. A great resource is your ink manufacturer – they can provide guidance on which inks and print processes are best suited for these types of substrates. Second, learn more about how it is dyed. Is it dispersed, cationic or sublimated? Each type of dye process can effect how much the dye will gas, which causes dye migration. Dispersed is a good dye process and is most commonly used by manufacturers. This process will migrate if confronted with high curing temperatures so you will need to use an ink with a bleaching agent/blocker to help reduce or stop the migration. Sublimation process is where a digital transfer has been heat applied to the fabric. This can create havoc on screen printers since this is not a stable dye process and does not react well to high heat. You will need to use extra steps like Carbon Base Blockers and high poly white inks to reduce or stop migration. Cationic Dye process is probably considered the best at stopping dye migration but this process is the most expensive. However, it does eliminate the need for expensive inks or extra blockers to battle migration

HELPFUL INKS AND ADDITIVES

There are a many different inks to help you achieve optimal performance. Nylon bonding agents, stretchy additives and silicone inks are just a few that will help you achieve quality prints on stretchy fabrics. Test them out to determine which works best for your shop.

• Stretch additives are an excellent choice and are also the most economical. Use 1-5% by weight, or follow the ink manufacturer’s recommendation for mixing the inks to give it more elasticity. There are also some stand alone inks that can be used as an under base for added security.
• If your garment has nylon in it, you will need to add a bonding agent/catalyst. This will help the plastisol adhere to the slick fabric. Otherwise, the ink will crack and flake off the garment. However, know that using a bonding agent will shorten the pot life of your ink, so mix only the amount you need for the project and allow plenty of time for the viscosity of the ink to thicken which will yield better coverage and opacity.
• Silicone inks are by far the best choice for overall quality and opacity. They produce an exceptional hand with softness, but the downside to using silicon is that it has a very short pot life of around 8 hours. Plus, it’s fairly expensive to use.

QUICK TIPS

Platen adhesive: Minimize the amount of adhesive you use to adhere the fabric to the platen. Since these types of fabrics stretch, it’s more challenging to remove the printed garment from the platen without warping or cracking the inks. It’s also beneficial to add an additional flash unit at the end of the print sequence to help gel the ink, which will minimize potential cracking.

Mesh Count: Using a 110-160 mesh will provide the best coverage and opacity for your base screens. Your top inks should be 160230 mesh, while your white overprint mesh should be 110-160.

Viscosity: Make sure you stir your ink prior to production to reduce the viscosity, which will help push the ink through the mesh to give you a better print surface.

Squeegee Pressure: Using light pressure is key. Keeping the ink on the surface of the fabric will help with opacity, hand and migration. If the fabric fibers work up through the ink it will increase the chance of dye-migration. Plus, if you apply too much pressure it will push the ink through the fabric which is an undesirable feeling to the skin when worn.

Tapping/Smoothing Irons: Poly inks are thick and can be rough to the touch, and when printing on performance, Heathers and Triblend fabrics hand is just as important as reducing migration. So smoothing your ink surface will improve the quality of the print as well as the hand or feel. To do this, use a tapping/smoothing screen in your first station to help lay-down any loose fibers. Print your base screen and flash, but instead of a cool-down station add another tapping/smoothing screen to even out the ink. Then, you can print your top color inks. It is recommended to use two white screens.

Screen Tension: Having the proper screen tension is key in keeping your ink on top of the fabric. Keep your screens tight and use a thin thread diameter. This will promote better lay-down without needing a lot of pressure, which will result in cleaner and tighter registration, and you can achieve a smoother surface with less mesh texture in your ink. If you have poor tension (too loose) in your screens you will have registration issues and will be forced to apply more pressure to get the ink through the screens. This will drive the ink through the fabric and allow fibers to work up to the surface of the ink, which causes dye migration.

Flashing and Curing: Proper curing is the most important step when printing on poly blended fabrics. Be careful not to exceed curing temperatures. Migration occurs around 270° degrees Fahrenheit/97.2° degrees Celsius. Don’t over flash or over cure your garments. Use inks that have a quick flash point. Flashing should only be a few seconds and keep temperatures below 200°degrees Fahrenheit. Reduce the number of flashes in your design. If you don’t have to flash, then don’t. Use inks you can cure at a lower temperature (between 250°- 270° degrees Fahrenheit). You should also slow the dryer belt speed to help the ink cure at lower temperatures.

No Stacking: Use fans and long cooling stations on your dryers to help cool down the garments faster. Avoid stacking garments until they are completely cool. Pressure and heat can accelerate any migration.

Follow Manufacturer Guidelines: Not all inks and substrates are alike. So, always follow the ink manufacturer’s suggestions. However, if you still incur challenges, don’t hesitate to contact your ink supplier for advice. Many ink manufacturers will offer their expert advice and possibly travel to your shop to help with your printing issues and needs.

In my years of experience I’ve found that following these simple steps will help in achieving the best results in screenprinting blended and 100% polyester fabrics.

Screen Printing Spec Sheet:

Recommended for Stretch fabrics such as the JERZEES® new Ladies’ Modal Stretch styles