In opposition to thermochromic inks, the thermic inks are whitish after printing and become coloured irreversibly when they are subject to high temperatures. 2 Temperatures are available:

A first family will react at a temperature of 75°C, and above this temperaure, the red or black coloration will remain visible.

A second family will react to 95°C with a coloration in blue, or black, or red, or green, and this coloration is irreversible only if a temperature largely superior to 95° is reach.