Dos and Don’ts of Heat Printing on Polyester

Since the rise of active wear and the popularity of athleisure apparel becoming a fashion trend, the need for decorators to find the best methods for printing custom designs onto polyester fabric.

When it comes to heat printing polyester, there are definitely challenges. The fabric seems difficult to decorate compared to the favorite cotton t-shirt, but don’t be intimidated by polyester.

In addition to already giving heat printers the benefits of wearing polyester and cotton shirts, we’re compiling the Do’s and Don’ts for Heat Printing Polyester so you can get the perfect print everytime!

Don’t Get Too Hot

Temperature plays a major role in heat printing custom apparel. You use a “heat” press to adhere the transfers adhesive or ink to the fabric. The problem with this though is some fabric (ahem, polyester) is sensitive to high temperatures and the fabric fibers can scorch (melt).

So you don’t end up with a permanent, noticeable rectangle on your t-shirts, don’t let your temperature get too hot! The ideal temperature is less than 300 degrees. Some polyester fabric is more sensitive than others and may require a temperature of as low as 280 to not see scorch marks.

How to tell if the apparel you’re heat printing is ruined.

Do Test the Fabric

The only way to know whether the polyester fabric will scorch or not is to test it. That’s right, get a sample of the fabric, fire up the heat press to a low temperature like 290 degrees F and press a small corner of fabric.

Did it scorch? No? Then up the temperature to 300 degrees. Press a small corner. Did it scorch? No? Up the temperature again to 310 degrees. Press a small piece of the fabric. Did it scorch? Yes? Then you know at what temperature the fabric scorches at. This will help you determine the right type of heat transfer to use.

Do Choose the Right Transfer Type

There are several different types of heat transfers at Transfer Express. Each transfer type has the type of fabric that it is proven to adhere to as well as the time, temperature and pressure that is needed to properly apply the transfer to the fabric.

Polyester is a common fabric that every transfer from Transfer Express will adhere to. However, some polyester is also temperature sensitive, so it’s best to look at the recommended temperature on the Application Instructions to know for sure whether it is the right transfer for the type of garment you’re decorating.

Transfer types like Elasti Prints®, CAD-PRINTZ® Opaque, Stretch Litho™ and AquaTru® , are all formulated to adhere at a lower temperature. These will be the best options for printing onto temperature sensitive polyester fabric.

Do Check for Dye Migration

Sublimated fabric example

Dye migration occurs when the fabric dye is reactivated during heat printing causing the dye to blend or migrates into the decorating material like ink or vinyl. This dye migration is common in polyester fabrics and fabrics that have been heavily saturated with dye.

Dye migration is extremely prevalent in Sublimated fabrics (pictured right). Sublimated fabrics are made by dying the fabric with a design or pattern. You can usually pinpoint a sublimated garment by looking at the inside of the shirt. If the shirt has been sublimated, the inside of the shirt is a solid color while the pattern or design is just printed on the outside.

If the fabric you’re decorating has been sublimated or the fabric you’re decorating is known to have dye mygration issues, choose a transfer type that is made to block dye migration like CAD-PRINTZ Sub block or AquaTru heat transfers.

Don’t Use Thick Cover Sheets

Cover sheets are designed to be placed over your heat transfer during heat printing. Cover sheets like thicker silicone application pads or non-stick 6 mil cover sheets can also help create a heat barrier to reduce scorching on polyester fabrics. While this might be a perfect solution for preventing scorch marks, what the thicker cover sheets are also preventing is the adequate amount of heat that is getting to your transfer.

Screen printed transfers need a precise time, temperature and pressure for application. If you prevent the right temperature from getting to your transfer, you run the risk of a decoration that is under applied.

Stick to thin, paper cover sheets that is sold by Transfer Express if a cover sheet is needed for your application.

Click Here to Leave a Comment Below 4 comments
Lisa Meyers

Thank you for the tips you shared on the do’s and don’ts of heat printing a polyester.

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Dealer Services

You’re welcome, Lisa! Glad you enjoyed the tips.

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Josylin

We are using elasta print transfers. Temp at 285. 15 sec. And 3 for pressure and still getting scorching on 100% polyester shirts. WHY?
WE also used paper on top.

Reply
Dealer Services

Hi Josylin,
Some polyester is super sensitive to heat. If it is 100% polyester, you can take Elasti Prints down to 275F. However, keep in mind that a cover sheet can also reduce the temperature reaching the transfer application by another 10 degrees. For proper application, you will also want to use medium-firm pressure (6-8).
Have you tested your heat press to make sure it is reading an accurate temperature? You may want to try this test kit: https://transferexpress.com/heat-presses/accessory/heat-press-test-kit

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