Because of the way the wool fibre is structured, wool requires more oxygen than is available in the air to become flammable. Wool is accordingly an excellent fibre when it comes to fire safety. Furthermore, it does not melt, drip or stick to the skin when it burns.
Of the commonly used textile fibres (cotton, rayon, polyester, acrylic and nylon), wool is widely recognised as the most flame resistant. Wool’s fire resistant attributes include:
A very high ignition temperature of 570-600° C
①、A high Limiting Oxygen Index (LOI) (the measure of the oxygen level needed to sustain combustion)
②、A low heat of combustion (the measure of the amount of heat energy released in the burning process)
③、Does not melt or stick
④、Self-extinguishing
Wool’s inherent fire resistance comes from its naturally high nitrogen and water content. Because of these, wool requires higher levels of oxygen in the surrounding environment in order to burn. Wool may be ignited if subjected to a significantly powerful heat source, but does not normally support flame, and will instead smoulder – usually only for a short time. In addition, wool’s cross-linked cell membrane structure will swell when heated to the point of combustion, forming an insulating layer that prevents the spread of flame. This also means that wool produces less smoke and toxic gas than synthetic fibres.
Lifesaving Applications for Wool：
Wool's natural flame resistance properties make it an ideal fibre for interiors such as carpets, curtains, upholstery and bedding as this will reduce the risk of fire spreading within a house. Wool textiles also protect firemen, military and anyone else exposed to fire or explosives. Wool's attribute of only smoldering and not melting or dripping into the skin, can be a lifesaver.
For more detailed research and background information access the IWTO fact sheet about Wool and Flame Resistance.