Wool – The Right Fibre for the Job

April 11, 2024

Wool is naturally flame-resistant, making it an ideal fibre for kitchen grease filters that help reduce the risk of fire.

Surprising but true, wool is naturally flame-resistant due to its high nitrogen and water content. It may be ignited if subjected to a significantly powerful heat source but does not normally support flame, and smouldering usually continues only for a short time. In addition, wool’s highly 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 mechanism also means that wool produces less smoke and toxic gas than synthetic fibres.

Wool is also a fabulous product for absorbing oil (grease). The Shepherd Filters team recently took the opportunity to demonstrate these claims in action, by using a heavily grease-laden wool filter media and putting it to the test:

Australian Wool Innovation Limited (AWI) has funded a new scientific study, undertaken by AgResearch, to test the fire resistance of nine fabrics used as base-layer garments for military and first responder personnel (i.e. firefighters).

The key concern with synthetic fibres (even flame-retardant ones) is that, when they are exposed to flame or extreme heat, they melt and drip which can result in molten polymer coming into contact with the wearer’s skin and burning it.

“In contrast, wool fibres are known to have a natural resistance to burning, even when exposed to an ignition source for long periods. This is due to wool having a high ignition temperature, high limiting oxygen index and its self-extinguishing behaviour,” said Angus Ireland from the AWI.

The results of the study can be seen below:

The fabric that performed best overall was the Zirpro^®-treated wool (100%) fabric which showed no apparent differences compared to the undamaged control samples (see A and B in Figure 2), in both the naked flame and accelerant tests.

Shepherd Filters are disposable kitchen grease filters made from 100% wool. Aside from being naturally flame-resistant, they are also fully bio-degradable and therefore, safe to dispose of in your regular waste bin!

Because wool fibres break down, it is the obvious choice for anyone concerned about the environment (and much safer to use than cleaning chemicals).

So when it comes to mitigating your fire risk and reducing commercial kitchen exhaust maintenance costs, look no further as wool has the right properties for the job!