Dye Sublimation (AKA Dye Sub)
Dye Sublimation is a 2-step process. The process starts by using special inks printed on to transfer paper. The transfer is then placed on the substrate (e.g. t-shirt) and heated to 400 degrees. The ink on the paper turns in to a gas and dyes or sublimates the substrate. The gas ink only bonds to polyester or oil based substrates (specially coated fabrics or hard goods). Because the ink is dying the current fabric color, the optimal color to work with is white. You can use other colors as a base but realize that color will interact with the gas and affect the result (think using yellow ink on to a light blue shirt the result will be green). You can use colored fabric but keep in mind the best results will then be with darker graphics (e.g. any color will accept black, the lighter the better though). The print will last as long as the shirt as the dyes are infused into the item at the molecular level rather than topically.