Merino Wool – Fire protection born in nature

February 2, 2018

Merino wool from Australia and New Zealand is widely regarded as the highest quality wool in the world. In recent years the excellent performance of merino has seen it become one the most high performance fabrics in use in sports, outdoor and military applications. Merino wool has excellent thermal properties, has a very high inherent flame resistance and protects the wearer whether it is wet or dry.

WOOL IS NATURALLY FLAME RESISTANT

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. In some respects, wool has a greater fire resistance that Nomex. Wool’s fire resistant attributes include:

  • A very high ignition temperature (570 – 600oC).
  • A high limiting oxygen index (20 – 25% with the LOI being a measure of the minimum % of oxygen required to sustain combustion
  • A low heat of combustion
  • A low rate of heat release
  • Doesn’t melt of stick upon burning
  • Self extinguishing
  • Formation of an insulating char when it burns
  • Evolution of less smoke and toxic gases than formed during combustion ofmost synthetic fibres.

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 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 protecting firemen, military and anyone else exposed to fire or explosives. Wool’s attribute of only smouldering and not melting or dripping into the skin, can be a lifesaver.

The propensity for textile to catch fire , and the manner in which they burn, is a key safety consideration for apparel. All fabrics will burn given the right conditions, however some are more difficult to ignite, burn more slowly, are easier to extinguish and combust at a higher (or lower) temperature.

Common textile fibres such as nylon, cotton, polyester and Rayon all have relatively low ignition temperatures and in some cases, will also melt prior to ignition (nylon and polyester). Technology has been developed to artificially impart flame resistance to apparel fabrics using chemical treatments during fibre manufacture, or as a treatment to the fibre, yarn or finished fabric.

Merino is naturally flame resistant, and it’s performance exceeds that of all other commonly encountered textile fibres. If merino comes in direct contact with another burning surface, it won’t melt or stick.

 

Flammability arises from the fibres’ unique chemical structure. Merino has a high nitrogen content (14%) and a high relative moisture content.

FIBRE

IGNITION TEMP (C)

MELTING TEMP (C)

MERINO

570 – 600

DOES NOT MELT

COTTON

255

DOES NOT MELT

NYLON

485 – 575

160-260

POLYESTER

485 – 560

252 – 292

RAYON

420

DOES NOT MELT

MERINO  WOOL – NATURES GREAT FIRE PROTECTOR