All fabrics will burn but some are more combustible than others. Untreated natural fibers such as cotton, linen and silk burn more readily than wool, which is more difficult to ignite and burns with a low flame velocity.
The weight and weave of the fabric will affect how easily the material will ignite and burn. Recommended fabrics are materials with a tight weave – wool, modacrylic, 100 percent polyester and those that are flame-retardant treated. Heavy, tight weave fabrics will burn more slowly than loose weave, light fabrics of the same material. The surface texture of the fabric also affects flammability. Fabrics with long, loose, fluffy pile or “brushed” nap will ignite more readily than fabrics with a hard, tight surface, and in some cases will result in flames flashing across the fabric surface.