Fire resistant paint is a substance that can delay and prevent the spread of fire for a specific period of time. It is important to remember that no substance is completely incombustible. The paint does not extinguish or stop fire; it only contains it and protects the structures to which it is applied. Fire resistant or fire retardant paint is intumescent, meaning it swells when exposed to high temperatures and increases in volume while decreasing in density. When fire resistant paint swells, it forms an insulating char that conducts heat poorly and allows more time for the fire to be contained by firefighters. Intumescent paint is a form of passive fire protection, which describes products that raise fire resistance and reduce the spread of a fire. These products also help maintain the structural integrity of a building and preserve lives by giving residents more time to escape before the fire becomes uncontrollable. Fire resistant paint carries a fire resistance rating that describes how long the product can withstand fire.