Size and Thickness of an Imprint: When printing a design directly on a T-shirt, a good starting point would be 1½ minutes at 320°F (160°C). A large athletic number printed on stretch nylon might require as much as 2 ½ minutes at 340°F (173°C). The greater the volume and/or thickness of plastisol on the garment, the longer the time and/or the higher the temperature required.
Color of the Ink: When fusing light colors under infrared lamps or solely infrared conveyor dryers, slowing down the belt speed may be necessary. Light colors may reflect infrared heat sources. With forced gas dryers, color is not that important, but watch the red and black colors for undercure.
Composition and Type of Fabric: The heat required to cure a plastisol imprint on a heavy cotton duck tote bag will be greater than the same design on a T-shirt. Many fabrics contain varying levels of moisture, water repellents, wetting agents, etc. Most textile fabrics containing any of the above would absorb more heat, and therefore a higher temperature or a longer dryer cure time would be required.
Dryer Type for Fusion of Plastisol: It is important to watch the difference between infrared and forced air dryers. The variables that relate to oven cure are:
Scorching– If a dryer is too hot it may scorch or discolor the garment you are curing. The answer is to lower the temperature to minimize scorching.
Dryer Hot Spots – Most conveyor dryers have varying degrees of efficiency. It is fairly common for gas burners malfunction and electrical sources burn out. Heat strips are essential in determining dryer efficiency.
Effects of Overloading the Dryer – Dryer efficiency is significantly reduced when the belt is completely full versus sporadic usage. Increase the heat output to reflect overloading in the dryer.
Weather and Environment Conditions – High humidity in the plant in the colder months or cold drafts will reduce efficiency. If a problem with heat curing is encountered, check all environmental variables.