Thermal wax is another specialist technology – very similar to dye-sublimation – well-suited to printing on transparencies. They use CMY or CMYK rolls containing page-sized panels of plastic film coated with wax-based colourants.
Thousands of heating elements on the print head cause the wax to melt and adhere to specially coated paper or transparency material. Generally the melted ink dots are binary, although some higher-end models have print heads capable of precise temperature variations, enabling them to produce multi-level dots.
Resolution and print speeds are low – typically 300dpi and around 1ppm – reinforcing the suitability of the technology for specialist applications only