The presence of moisture in either the substrate or the transfer paper results in an adverse effect on the sublimation process. They can lead to issues like color shifting (losing colors accuracy), bleeding of the image, and uneven transfer of solid filled areas of a design.
Sublimation paper can retain an enormous amount of moisture. To minimize the effects of humidity, always keep your transfer paper sealed in a plastic bag in a dry place. If possible, store your sublimation paper in a temperature and humidity controlled environment.
If you suspect the transfer paper is exposed to humidity and have excess moisture, you have a couple of options. One is to set the paper on your heat press without closing it for a few seconds to warm them. The heat radiating from the press should help in evaporating the moisture.
If you’ve already printed a transfer you can place the printed transfer 2″ to 3″ below the heat platen for 30 – 40 seconds to eliminate the excess moisture. This may results in the transfer like missed color or fuzzy looking details.
However, an environment that is too dry isn’t any good either as it can cause print head nozzle loss issues.
The best environment for sublimation printing is one that has at least 45% humidity and is reasonably cool. If adjustments are needed, you can purchase either a humidifier or de-humidifier.