Pressing Heat Transfer Films

Heat Press Temp Setting

Successful application of heat transfer materials depends on three primary variables: time, temperature and pressure. Not all heat transfers heat press at the same setting. Hotter is not always better. In fact, higher temperatures can make matters worse. Before heat pressing, refer to the manufacturer’s literature for the recommended time and temperature settings. 

Pressure is equally important.  Many times a heat transfer will not adhere properly because of inadequate pressure. Increasing the temperature setting or dwell time usually will not help. The manufacturer of the heat transfer material will have recommendations for the correct settings in their technical bulletins.

Press Warm Up. Heat presses take time to warm up to the optimal temperature.  About thirty minutes prior to production allow your press to warm up.  Set your controls for the time, temperature and pressure settings recommended for the heat transfer films that you will use.Preheating the Garment. Prior to heat press transfer of the graphic, always press the garment for three to five seconds. This serves three important functions. First, it drives off moisture, which could inhibit adhesion of the heat transfer material. Second, it presses the garment smooth, eliminating wrinkles so the heat transfer has a smooth surface to adhere to. No wrinkles in the garment, means no wrinkles in the graphic applique. Third, preheating the fabric will cause it to shrink.  That’s a good thing, if you are layering several different materials. Without preheating, the shirt and the first layer of graphics will shrink together.  That will make registration of subsequent layers impossible.
Will preheating prevent further shrinking as the garment goes through multiple heat pressings?  Not always, so there are other fixes that may work, such as allowing for overlaps when you are designing the graphics.Registering Graphics. After you weed the matrix of plotter cut films, you will turn the graphics over to position the graphic on the garment.  The clear liner allows for accurate registration, which is critical when doing layered graphics.  With the material in position (the carrier should be on top now), the graphics should now be “right reading”.  For printed appliques, using a clear HotMask will facilitate alignment.
Registering Graphics

Registering Graphics

Be sure to carefully measure the graphics, to prevent misalignment of graphics. To aid registration, several tools and templates are available on the market, such as the Tee Square It™ tool or alignment grids.

After you position the graphics on the garment, you can cover the graphics with a Teflon® blanket (optional).  While this blanket will evenly distribute the heat, the main purpose is to protect the top platen. If you use a Teflon® blanket, you will likely need to increase the time for pressing.

Removing Carrier

Removing Carrier

After pressing the material, peel off the carrier or HotMask transfer tape as shown in the photo below. Whether you should do a warm peel or a cold peel depends on what type of heat transfer film used. Refer to the manufacturer’s application information for recommendations.

Proper Prior Preparation. Most of the standard heat transfer films are designed for application to cotton, polyester and cotton/polyester blends.  Prior to production, refer to the manufacturer’s literature regarding compatibility of the film to the fabric. Some fabrics, such as the popular performance fabrics or nylon, required either a low temp film or an adhesive designed for coated fabrics. If you have any questions, call your supplier. Usually they will have the information you need. Of course, since the manufacturer cannot possibly test and evaluate every film/fabric combination for compatibility, you may need to test the film yourself to ensure its adhesion.

Note: When applying heat transfer materials to thicker garments, you may need to increase the dwell time and/or pressure to achieve good adhesion.

Layering Graphics. Combining different materials in apparel design creates visual excitement, which can be your competitive edge in selling heat transfer graphics. Think of the possibilities of combining colored flex films with a metallic film or a flock film.  You can create designs that are unique and different and difficult to reproduce using other techniques, such as screen or digital printing.

The layered graphic shown below combines a black polyurethane base film with a silver metallic flex film and a red flock film overlaying it.

Finished HTM Graphic

Finished HTM Graphic

Layering multiple color designs involves cutting, weeding and heat pressing each color of film separately.  In heat pressing one color over another, make sure that the carrier covers and protects all of the different layers which have been applied.

About the author . . .

Jim Hingst, is a recognized authority in the field of vinyl graphics application. In Vinyl Sign Techniques, Hingst provides a comprehensive guide to the vinyl graphics business. Built around his firsthand experiences working for major fleet graphics screen printers and pressure sensitive manufacturers, Hingst offers a perspective on the vinyl business that thoroughly covers sales and marketing, materials, fabrication, and installation and removal of vinyl products of all kinds. Vinyl Sign Techniques has something for everybody in the vinyl graphics business. Hingst’s book, provides ideas and techniques for graphics fabricators and installers along with advice for executives and salespeople that will result in higher sales and profits.

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