During production with a heat press operating at 400 F/204 C, moisture can flash to steam and blow the ink away from its intended target. Some of the problems that are attributed to moisture include color shifting (colors lose accuracy), image bleeding, and uneven transfer of solid-filled areas.
Under normal circumstances, a small amount of moisture can accumulate in the transfer paper and is usually absorbed directly into the substrate during pressing. However, hard substrates, like metal and ceramic, are unable to absorb excess moisture. Thus, it’s important that you take steps to minimize the introduction of moisture into the process.
The first step is to protect the paper from moisture absorption. As a preventative measure, store your paper in a dry place. Consider a sealed container such as a resealable bag. If you suspect moisture, set the paper on your press for a few seconds. Do not press it; just expose it to the warmth. The heat radiating from the press should help evaporate most of the moisture.
Another trick is to use newsprint or butcher paper instead of a Teflon sheet. The paper will help absorb moisture from the transfer sheet during pressing, whereas Teflon will not. Be sure to use a fresh sheet of paper for each pressing cycle.
In addition to being mindful of moisture in pressing, you should also focus on your work environment. High humidity levels usually contribute to moisture issues. A dehumidifier can help control these issues, but reducing it too much can have negative effects on the inks and your equipment.
It’s wise to invest in a hygrometer and take some readings. The ideal operating conditions for sublimation are 59 F to 77 F or 15 C to 25 C with above 35 percent relative humidity (no condensation).
-Jimmy Lamb, Sawgrass