Thread: Danish oil on fire

I tend to throw the oil/shellac/glue rags out on the grass, then pick them up when they are dried.

Works well. I'm too chicken to leave them hanging over the edge of the bin.

Originally Posted by Wongo

Been reading the AWR #39.

In page 43 it reads “Please note, that oil soaked rags may self-combust and have the potential to burn your workshop down”

So what does it mean? How likely is it? Would a piece of cloth soaked in Danish oil self combust under room temperature? or maybe in a hot day say 150°C?

I always just put them in the bin and sometimes the bin is full of saw dust.

Anyone?

Seen it happen twice. Once in a work truck and once in a shop. Truck was a right off the shop was saved cause the guy throwing the rags away got lucky and used a metal can instead of the usual plastic gabage can. I asked the guy if he used the metal can on purpose because of the danger and he said he had never heard of that before. The rags weren't screwed up tight just thrown in behind the seat of the truck and simply tossed into the bin. hey don't need heat as they make their own when the oil begins to dry. If there's enough insulation to allow a build up of heat they burst into flames. I always with out exception hang the rags up and let them dry for a couple days before I throw them away. Have tried to induce it myself to see how long it could take but found tying the rag in a knot didn't work. A hot day will only speed it up and make it more likely to happen.

Posted by Wongo
Been reading the AWR #39.

In page 43 it reads “Please note, that oil soaked rags may self-combust and have the potential to burn your workshop down”

So what does it mean? How likely is it? Would a piece of cloth soaked in Danish oil self combust under room temperature? or maybe in a hot day say 150°C?

What part of Hades do you live - 150"C . . .
Jedo

Hell!

Not I mean Queensland.

Thank you all for the reality check and links to the sites.

Have crumpled up rags before - not warm - no problem - therefore probably myth - having looked and now done some further digging I think I can say [my] "myth busted".

It may never happen to you but it is a real threat so why take unnecessary chances. Must admit I have been guilty in the past of not doing the right thing but this thread has given me the wake up call i needed.

If you want to try it, just spill some loctite 406 & wipe it up with a nylon rag. Bunch up the rag & toss it in a metal garbage bin.

Did that in the old factory one night, turned around 5 minutes later & the bin was smouldering.

When I told the dayshift boys, they didn't believe me, so they all tried it themselves & it worked every time.

What is the situation where the rags are place into a sealed metal container? I have tested this and found that there was no heat build-up in rags in the tin. But perhaps my experiments lacked something.

I keep my standard shellac applicator in a sealed small plastic container and have seen no heat build-up there either, and cloth does not harden-up.

Rags that I have finished with go out on the lawn before going in the garbage bin.

I do not throw out rags used for tool cleaning until they are sufficiently dirty, these do not have non-drying oil on them - only dirt and WD40 usually. They are not in a sealed container, and I understand do not self-combust.

I think that shellac might be different as it cures more because of the solvent evaporating rather than a chemical reaction with the atmosphere like dansih oil etc. Another thing about having it in a sealed metal container is the lack of oxygen to start (or maintain) combustion.

Ping

Paul Chapman has posted a link to this experiment on the Woodwork UK Forum: http://wildwoodsurvival.com/survival...l05/index.html

So yes, Wongo, you can do it. I imagine that if the cloths were of a more combustible fabric than cotton (eg polyester) the experiment might be more spectacular!!

This effect happens specifically with the so called "drying" or polymerising oils, like linseed and tung. These are traditionally ingredients in the so called Danish or Scandinavian oils.

However, many commercial so called "danish oils" are really far closer to wipe on poly in formulation, and may not show the effect to the same extent. With high levels of drying oil, however, it can definitely happen.

Requirements are:

High drying oil content.
Large surface area; i.e. rags, sawdust ( to allow oxidation to take place over a large area)

Insulation to allow heat build up; i.e. piled up or bundled together, and enclosed in bin.

Along with this, critical mass. Far more likey to happen with a big pile of rags than with one small piece.

Given the above, temperatures well above the 150C will develop in a relatively short time, until the ignition point of the combination of rag and oil is reached, then "wooshka"

To the extent that in the edible oils industry, when processing linseed, it is necessary to blend it at least 50/50 with other non oxidising oils, to reduce the risk of ignition of used filter earth .

regards

Or, for the impatient, mix Condy's Crystals (Potassium Permanganate) with Glycerine. Only takes a couple of minutes. Also fun for the kids.

My wife used 'Danish oil on our household furniture some weeks ago during a cleaning spree and placed the oil soaked cloths into our new 120 litre plastic 'Wheelie bin' for Council pickup.
I went out into our backyard after watching a movie at about 10:30 pm and the backyard was lit up like 'Luna park' and was filled with black acrid smoke.
You guessed it the bin went up in flames
I can't understand that the neighbours didn't kick our door down as the whole suburb was smothered in black smoke and the smell of burning rubbish
Fortunatley only the bin was completly destroyed along with our household rubbish and the corro. fence was blackened [nothing that a coat of paint didn't fix].
I recently retired from the local Council so I still had some contacts that I could approach to replace the bin after some explaination and good humoured chiding that was to be expected!
The outside temperature that day was around 35deg in the shade or better

Thanks Ron, that reminded me that I had left my BLO cloths in a pile under the skylight in the shed!
Cheers