Class B vs. Class A
Once dried out, the latex and alkyd paints are no longer flammable. The coating and the surface are included in the rate of flame spread. The flame rating and spread of both surface and coating are preferred to be lesser than 25, which means using an A class rating as it has lowest flammability rate. A surface like drywall, concrete, and metal is noncombustible. Hence less flammability can be attained through application of latex and alkyd paint. Class “B” flame spread rating lies in the range of 25 to 75, with coating and surface combined. On wood, Class B or Class A rating can be attained only with the use of fire-resistant paint.