Flame retardant textiles are found in a variety of textile products ranging from clothing, to automotive textiles, to home furnishings. Depending on chemical nature, there are four main classes flame retardants. These are inorganics (e.g. aluminum trioxide and magnesium hydroxide), nitrogen-based organic, organophosphorus (e.g. phosphate esters), and halogenated flame retardants Flame retardants may also be classified depending on their fastness to laundering as non-durable, semi-durable, or durable. A nondurable finish does not withstand laundering and must be reapplied. Semi-durable treatments fall in between nondurable and durable. Depending on the end use of the product, the durability of the treatment is important. For example, apparels should have durable flame retardant treatment since they are washed regularly while home textile fabric would not.Flame retardants are evaluated for many properties during burn testing including char length, after-flame and afterglow times, and melt drip. ASTM D 6413-99 defines char length as the distance of visible fiber damage beginning at the bottom edge where the flame was applied. After-flame time is a measurement of how long a substance continues to flame once the ignition source is removed and afterglow is how long a substance glows after the ignition source is removed. Self-extinguishment is defined as when the glowing or flaming of a specimen goes away after the flame source is removed.