Flame-spread

Class A Vs. Class B

Alkyd and latex paints are not very flammable after they have dried. The flame-spread rating of a paint includes both the surface and the coating applied to it. A Class "A" rating is the lowest flammability rating and the flame spread of the surface and coating combined must be less than 25. This can be achieved with alkyd or latex paints applied to noncombustible surfaces such as concrete, drywall, and metal. For a Class "B" rating, the flame spread of the surface and coating combined is between 25 and 75. A Class A or Class B rating can only be achieved on wood by using a fire retardant paint.