Don’t Worry, Be Stretchy: Introducing FN-INK™ Stretch Plastisol Ink

Once in a while, you may receive an order where the print needs to be real flexible like it can stretch far without falling apart. All ink can stretch, to a point. When it needs more support to make it extra pliable, then you need stretch ink.

A stretch ink makes an ink more flexible so it resists cracking or splitting on stretchy garments like spandex, leggings, and yoga pants. FN-INK™ Stretch is designed to be used as either an under base, mixed in with a base white, or as an additive for colors that need even more pliability. Let’s look at when and how you’d use the stretch ink in production.

WHEN SHOULD I USE FN-INK™ STRETCH?

Say you’re contracted out by a local high school dance team. They want leggings with their logo printed on the thigh. Leggings stretch and shrink to fit the person wearing them. To extend the lifespan of the print and ensure it doesn’t crack, you’d need to use stretch ink. That’s where FN-INK™ Stretch comes in. It’s meant for printing on garments that are going to be stretched significantly, like wrestling singlets or spandex (or the leggings just mentioned). When cured properly, the ink will resist cracking or splitting when stretched beyond an ink's normal limits. 

The right time to use FN-INK™ Stretch comes down to a judgment call. How much is that print going to stretch during the garment’s lifespan? If the garment is going to be stretched a lot—like a wrestling singlet—it’ll need more stretch. Adding FN-INK™ Stretch to colors as well as the under base will give you more and more stretchability. 

HOW TO PRINT FN-INK™ STRETCH

As with any specialty ink, there are some nuances to using FN-INK™ Stretch. Depending on the garment you’re printing on and its intended uses, you’ll use the stretch ink a little differently. 

FN-INK™ Stretch can be used in three ways: as an underbase, as a base white, or mixed in colors. How do you decide which route to take? It depends on what you want to do and what kind of stress the garment will go under. If you want to save ink and keep things straightforward, print the stretch as an underbase and print the colors on top of it. The stretch underbase will act as scaffolding, and the colors on top will bend and flex easily. But if the garment will be stretched a lot (like a wrestling singlet), then you may want to mix the additive as the base white and/or in the colors. With each of these techniques, there are best practices to follow. Let’s take a look at each one.

USING FN-INK™ STRETCH IN COLORS

If you’re printing directly to the shirt fabric, add 10%-25% by weight into the color. Depending on the needs of the fabric—i.e. how much it will stretch over the garment’s lifespan—you may need to add more than 25% of the stretch additive into a color. 

If you’re going to need more stretch out of a print, consider printing a stretch underbase to improve the flexibility of the ink layer. 

REMEMBER: Some colors are inherently translucent and any addition of a clear additive can create a loss of opacity or coverage.

RECOMMENDATIONS FOR PRINTING A BASE WHITE

Add up to 50% of FN-INK™ Stretch into the white ink. This will greatly improve the stretch performance of the print. Overprint the colors as normal. In some cases, you may need to add 5% stretch to the top colors.

If your shop is printing on a lot of stretchy fabrics, adding FN-INK™ Stretch to a base white is a great idea. If you’re not going to be printing on these types of garments often, consider printing FN-INK™ Stretch as an underbase by itself. 

PRO TIP: While you can add as much FN-INK™ Stretch as you want to ink colors, anything above 20% will begin to cause a drop in opacity. Be aware of this fact when mixing, and always test before production.

USING FN-INK™ STRETCH AS AN UNDERBASE

If you plan to use FN-INK™ Stretch as an underbase, start with a lower mesh screen (86–110). Print a smooth deposit of FN-INK™ Stretch, and flash until it’s dry to the touch. Next, print the base white and colors you’re using for the print. 

Why would you want to use the stretch additive as an underbase? Some fabrics undergo lots of continuous stretching. Think about that dance team again: the leggings you print for them will probably undergo lots of stretching over the course of the garment’s life. The more a piece of fabric is being continuously stretched, the more it may need a more flexible underbase.

If you’re printing on a highly flexible fabric, you may need to add 5%-10% FN-INK™ Stretch (by weight) to the top colors. The stretch additive will provide additional stretch and flex. In extreme cases, you may need to print-flash-print the FN-INK™ Stretch base before over-printing the colors. Perform many tests to dial everything in before production. 

GENERAL PRINTING TIPS

As always, stir the product prior to use. It’s recommended to print a thicker ink deposit than normal when extra stretch is needed in any print. Thicker ink deposits have greater resistance and durability to repeated movement. Remember, thicker ink deposits take longer to cure. Perform a wash test to ensure proper cure before you head to production. 

Set the screen up with a slight, increased off-contact to compensate for the thicker stencil and ink deposit. It’s recommended to use a 70 durometer or a 65/90/65 squeegee blade. You’ll want a thicker deposit, but using a blade that is too soft will not properly shear the ink while a squeegee with a stiffer, or harder blade will result in a thin ink deposit. Using a squeegee in the middle is the best route.

When possible, do a flood print. The flood stroke will pre-fill the thicker stencil and make it easier to fully clear the ink from the screen. It’ll produce a smoother ink deposit. It is recommended to do two passes with the squeegee to ensure a thicker ink deposit.

Pro Tip: FN-INK™ Stretch is not a low bleed ink. Adding it to any ink that has low bleed properties will reduce that ink's ability to slow down or stop dye migration.

CURING FN-INK™ STRETCH

Since you should be printing a thicker ink deposit when using FN-INK™ Stretch, you’ll need to adjust and test the conveyor dryer to find the best settings. Remember that thicker ink deposits take longer to reach full cure. A longer dwell time will be needed to reach full cure.

FN-INK™ Stretch is a low cure product, but it remains stable at higher temperatures. The ink can be used with standard cure inks of 320°F. Even though it’s a low cure ink, FN-INK™ Stretch will be just fine in higher temperatures.

STRETCH AND WASH TESTING

When testing cured ink, perform a wash test to ensure proper cure prior to going into production. 

Do not perform a stretch test for 24 hours after cure. All plastisols go through a settling phase where they continue to crosslink for 24 hours. The settling phase is more pronounced in inks with high elasticity. When performing a stretch test, don’t go overboard. The purpose of the garment is to give and stretch as the person moves. Just because you can stretch it to 300% elongation, doesn't mean you should.

FN-INK™ Stretch is a low-cure stretch ink that can take plastisol printing to new lengths. You’ll be able to print on athletic garments with ease. Use FN-INK™ Stretch as either an underbase or an additive to extend the boundaries of your plastisol printing game.

 Original Post:  Jacelyn Wedman  |  Apr 25, 2022  - Compliments of Screenprinting.com