Any problems with heat press transfers will lead back to the three variables of heat pressing: time, temperature, and pressure. With all sorts of different substrates, transfer inks, and transfer papers, it is critical that you know the correct settings for each variable in order to produce an optimal print. If even one of these variables is incorrect, then it can lead to a wide variety of issues with the “finished” product. Knowing exactly what went wrong can save you from making the same mistake in the future, or in some cases allow you to rescue a substrate you have already printed.
Now, before we get to the troubleshooting, you should know that most of this article’s help will not be necessary if you have taken the time to test your prints. When testing a print, it is important that you are printing on the same type of garment, and ideally even testing the same color. By testing beforehand you can eliminate not only wasted time, but loss on poorly printed products. Polyester products, for instance, are typically more expensive than cotton and trickier to press. High temperature and pressure can leave an irreversible box on the garment. If the box is in the shape of the press, then the temperature is too high. If the box is in the shape of the transfer paper, then the pressure is too high. So, with polyester garments it is important to experiment with lower temperature, and especially lower pressure. Print Phase actually offers a low-temperature, low-pressure transfer for polyesters that should eliminate these issues. However, even with proper testing, you may run into some issues during pressing.
On darker garments, transfer ink can sometimes appear to have weak opacity, appearing faded rather than vibrant. For instance, white ink on a red shirt might appear slightly pink. To prevent this, allow the transfer to cool for a few seconds before removing it, and test decreasing the pressure and/or time. If the ink from a transfer does not properly adhere to a garment, lifts up at the edges, or fine details do not transfer at all, then increase the pressure and/or curing time for the garment. Another common issue with heat press is the transfer’s release. Release problems are typically related to the pressure. If there is too much pressure, then any already-pressed garments may not be salvageable. If there is too little pressure, then the ink will not release completely onto the garment. If this is the case, then raise the pressure and re-press any garments that had this issue for the full press time and they should turn out fine.
There is a simple fix if your transfer design bleeds through the back of the garment. Just thread the next garment onto the platen of the heat press and it is no longer possible for the ink to reach the back of the garment. This is only a problem with a few colors of garments: charcoal, purple, and gold. This can affect other colors and types of garments, but the aforementioned are the most common. It is recommended to always thread garments when possible, as it eliminates this staining and several other possible problems with pressing (like creases or folds in the shirt).
If your prints have creases, lines, or even opacity problems after printing with kraft or parchment paper, then simply replace the paper. Kraft paper can be a useful tool should a garment fail the stretch test. Simply press the garment again with Kraft paper for half of the original time and it should be cured properly. It is time to replace Kraft paper when it darkens, and when parchment paper yellows. Kraft paper will usually last much longer (hundreds of prints) than parchment paper before it must be replaced, but it is important to note that neither lasts forever.
While it is important to test all your prints prior to production, you will still occasionally run into issues when pressing a garment. It is important to know which variables are responsible for different issues, and how to manipulate them to your benefit. Being able to fix issues on the fly is critical for any business, and especially critical to product decorators who lose money and products with every mistake. With some experience, recognizing these issues and knowing how to fix them will become second nature. Until then, you have this guide to look back on for help troubleshooting heat press transfer problems.
