Traditionally, IFR fabrics have been defined as fabrics constructed with yarns manufactured with FR additives. This process imparts Permanent Flame Retardant properties to a fabric over its service life.
Many conditions affect the flame resistance of a fabric: how the fabric is used; what other fabric or non-fabric components are added to the base fabric; environmental conditions such as sunlight, dust, humidity, etc., length of time in service, sewing, printing, painting or any other added processing steps.
Fabric has been treated with a non-permanent, registered, FR chemical at the Mill by a certified applicator. This is a topical treatment, usually water soluble, and has limited service life. 100% FR cotton fabrics cannot stand up to high humidity, or washing. Flameproofed polyester fabrics have greater durability and longevity, but in many cases still require subsequent re-treatment.