An expensive, brittle metal used to make the shadow mask in a direct-view colour picture tube. Incorporating it allows higher picture contrast levels from the tube without incurring long-term damage to the shadow mask itself. It allows the set manufacturer to offer higher contrast levels.

Since the phosphors in the tube reach the point of blooming well before the need for the Invar mask, anyone properly setting the contrast level for no blooming in the picture won’t ever need the features of the Invar mask. The high contrast levels permitted by the Invar mask will eventually burn the phosphors.