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Last night I was testing the finish of Boiled Linseed Oil on some timber I'm using for a project (never used it before) and read the following on the bottle.
"Soak rags in water to avoid Spontaneous Combustion"
This freaked me out a little bit and made me glad I read it as I normally would have thrown the rag on my bench. How likely is that a rag will Spontaneously Combust?
HH.
VERY
ask your local fire station
So should I be keeping this stuff in a metal box? Is it a reaction with air or with the rag? What about brushes?
HH.
http://www.woodworkforums.ubeaut.com...ous+Combustion
All you ever wanted to know....
Forensic fire investigators will tell there is no such thing as spontaneous combustion. What there is is heat, fuel and oxygen. We tend to state something spontaneously burst into flames when we don't understand how or, mainly that the heat/ignition source is a chemical reaction. There is always a reason.
Hang your rags clothesline style, lay them flat without any scrunching or better still wash with warm soapy water. With linseed the rag needs to be all bunched up so that heat can build up. It very often gets quite hot particularly in warmer weather or where sun is shining through a window. It rarely bursts into flames but its something you need to be weary of.
Cheers
You're looking a bit weary in your picture there, Squizzy.... ;)Quote:
something you need to be weary of
I always take my rags that have been used for oils and stains etc out to the back yard where they can burn without taking out my shed if they so desire.
I haven't had any self combust yet but I am acutely aware of the consequences if they do catch fire.
- Wood Borer
Silent,Quote:
Originally Posted by silentC
He's from the state of sand so it's possible the sandman has been giving him a double dose.
- Wood Borer
You guys aren't really taking this serious are you. I am the Sandman!:) (Well I'm the wheelbarra sandman at the moment).Quote:
Originally Posted by Wood Borer
I did actually have some rags get quite hot when I was a kid, oiling my cricket bat with linseed. The old man found them and I got an a**e kicking that has been sufficient to keep my rag hygiene practices sound ever since.
As has been stated on the thread referenced above, it is oxidation which might cause oily rags to spontaneously combust - particularly if they are scrunched up together. Just flattening the rags to dry is enough to prevent it.
If you want to actually witness spontaneous combustion, get yourself some potassium permanganate and glycerine. Both readily available in chemist shops (at least in UK - often on the same shelf :eek: ). Potassium permanganate (sometimes called 'permanganate of potash') is a powerful oxidising agent, and glycerine is a sugar 'fuel' which readily oxidises. They both have 'normal' uses! Just add a few drops of glycerine to a small pile of the purple crystals (in a safe place of course!) and in just a couple of minutes it will combust. We used to do this as kids and grew out of it, but I remember it being quite spectacular. It does not burn too fiercely so is a relatively safe way to prove that spontaneous combustion is indeed possible.
The way oils 'cure' is by oxidation, and oxidation is an exothermic reaction (produces heat); the faster the oxidation process, the more heat. So in ideal conditions (warm day, rags scrunched up so the heat is not dissipated, etc.) oily rags will indeed behave the same way as the experiment described above.
I agree, it's oxidation of the oil that produces heat. The oil on the cricket bat oxidises and the heat dissipates quickly. The oil on the rags oxidises as well but:
1. Because of the nature of the rags, you have a much bigger surface area for the oil to oxidise from, hence more heat, quicker,
2. Throwing rags in a pile or worse still, in a bin, helps to conserve heat within the pile of rags, hence more heat, quicker oxidation, more heat..etc. then "whoosh", up she goes.
Remedy: soak rags in water until oxidation is complete, or as I do, lay the rags out flat, in one layer until stiff and dry (oxidation is complete and nothing to build up heat and hold it) then dispose of.
Sorry, that should be 2.2c (inc. GST)
Speaking as an exinsurance assessor I can reiterate what everyone else has said, Linseed oil and the like are a real fire hazard, you just need to know the risks and take the suggested measures to prevent it.
I've known of many businesses lost because of this problem/effect, Timber blind manufacturers and garden furniture manufacturers are usually questioned closely about work practices involving the stuff.
Just to prove it to myself I once soaked a rag in linseed oil scrunched it up and left it out in the yard on a sunny day. it took less than 10 minutes to ignite
Dave
Only just last week in Tamworth a General Store and Post Office went up in flames from oily rags left in a bucket inside the shop.
Did quite a bit of damage to the shop.