Monday, December 17, 2007

Is Wool Self-Combustible?

Penny had trouble mailing yarn again. In my quest to get to the bottom of this issue, I've submitted the question to Quirks and Quarks:
A friend of mine continually has problems mailing packages that contain wool. She is told by the postal worker that it's listed in the book of dangerous goods as being highly flammable. Recently I was listening to the Car Talk podcast, and Ray was reading from Philip McCutcheon's book "Tall Ships":

"Spaced along the upper deck were the cargo hatches with their heavy covers of reinforced hardwood planks, well chocked in and secured with three separate layers of tarpaulin, held down with ropes and more chocks to withstand the pounding of heavy seas. Below the hatches lay the reason for the ship's presence on the sea, her cargo, to be held inviolate against nature and disaster, against fire that could come from a self-combustible cargo like wool, or a cargo that could swell when it met water, such as rice."

Why is wool considered highly flammable or self-combustible, especially when wet? I have not heard of sheep in Britain (where it certainly rains) self combusting in the fields. As a knitter, I have never had my wool yarn self combust, even while washing it. In fact, one test to see if a particular yarn is wool or not is to see if it self-extinguishes after being held to a flame.

Is wool dangerously flammable or self-combustible?

Thank you.
(No, Car Talk hasn't answered me yet.)


Anonymous said...

omly said...

As an avid Q&Q listener, I hope they follow up on this.

Kelli said...

How about this? From the German Transport Information Service:

"RF Self-heating / Spontaneous combustion

Oil content: 10 - 20% (wool grease)

Raw wool is an animal fiber. Animal fibers (burnt, wet or damp) are assigned to Class 4.2 (Substances liable to spontaneous combustion) of the IMDG Code and ADR.

The high content of wool grease makes greasy wool even more highly flammable than combed top and it may be easily set alight by sparks, cigarette ends etc.. Its high keratin content also makes it liable to self-heating/spontaneous combustion, particularly through the action of moisture and fats/oils. It should not be stowed in a hold/container together with foodstuffs and animal feed or with animal or vegetable fats/oils. Oil-saturated wool quickly succumbs to self-heating/spontaneous combustion and may burn for weeks without being discovered. It is also important not to stow greasy wool over barrels containing wool grease, as there is a risk of self-heating. Smoking is absolutely prohibited.

The hold must be equipped with a CO2 installation, as water is unsuitable for extinguishing a fire due to the considerable damage caused to the cargo and the capacity of wool to swell by 30%."

noricum said...

Okay... reading stuff (and doing extra searches) from the link provided by anonymous (thanks for the link... who are you?), wool is *both* self-extinguishing/flame-retardant *and* self-combustible. It seems somewhat oxymoronic to me.

However, the self-combustible wool appears to be grease wool (unscoured wool), in large quantities, wet, and compressed. So you would think that if we were mailing parcels smaller than a sheep (I don't think I've ever tried mailing larger parcels) of clean wool/yarn, that is dry and not excessively squished (admit it... we all try to fit as much as possible in our packages), that the post office could manage not to soak our packages and set them on fire?

Penny said...

OK OK I get all that wool grease stuff but still sheep have lanolin in them and some have more lanolin in them than other and the sheep grave in flocks yet I still haven't heard of any sheep or flocks of sheep self combusting. Well, maybe if they got sturck by lighening but we are not talking about lightening strikes. Ligtening strikes are not the commom ocurrence I would expect to happen to the plane that had my package of yarn in it.

Allergy Mom said...

Hmm...back in the fall last year, my mom sent 2 wool sweaters for my daughter. The mail workers in India check the contents of every package being mailed to the US, apparently for extra security guidelines. Their guidelines didn't say anything about wool being dangerous.

noricum said...

I'm glad *someone* writing guidelines has some brain cells! ;)

Gordon said...

i was speaking to my father today ( a station owner from wayback ) and this topic came up. He mentioned that it is to do with raw wool having just being shorn and baled, having high organic matter in the wool and under compression if it gets wet it heats up like a damp hay stack and can combust or smoulder due to the excessive heat.

noricum said...

Thanks for the information. It's silly to apply the same rule to wool that's been processed into clean yarn or roving, though.