Thermochromic inks are inks that change color with changer un temperature. They are available in two main types; reversible dans irreversible. Reversible thermochromic inks are generally used to show when the tempature of a pack or label has reached an optimum level. For example, when the temperature of a beverage is at the appropriate level and ready to serve the thermochromic ink label will change from white to blue. When the product warms up the message will disappear.