The point where a polymer changes from a hard glass to a soft rubber is called the glass transition temperature. This concept is illustrated in Figure 2. A material with a higher glass transition temperature requires more heat to make it soft. In sublimation printing, the coating is softened by heating it above the glass transition temperature. Meanwhile, heat turns the solid dye into a gas.
Pressure forces the gaseous dye into the softened coating.
The coating then cools below its glass transition temperature into the hard glassy state, freezing the solid dye into the coating. Sublimation Problems Problems encountered in sublimation are usually rooted in the process described in Figure 1. Abnormally Shaped Parts. The uneven surfaces of ceramic parts can cause problems with sublimation. An uneven surface prevents even application of pressure, which is necessary to direct the gas to the part.