Definitions for "Intumescent"
Keywords:  char, swell, exposed, unabridged, flame
Swelling up; expanding.
(adj.) of paint : swelling and charring when exposed to flame (Merriam-Webster's Unabridged at www.m-w.com) (date: 1953)
A fire-retardant technology which causes an otherwise flammable material to foam, forming an insulating barrier when exposed to heat.