Spontaneous combustion?

[White House Workshop]

Today I received another litre of tung oil and it came with the now familiar warning that rags and cloths soaked in it can spontaneously combust. I've been using this oil for getting on for 20 years now and have had quite a lot of rags, both oily and dried out, lying around and none of them have ever shown the slightest sign of bursting into flames. Maybe it's because they're usually left open rather than scrumpled up or in large quantities, sometimes on a bench or even on the floor, to dry out, and some have simply been thrown away.

So what do you think is the real scoop on this spontaneous combustion statement?

Incidentally, the bench tops from Sarah are looking totally amazing after their third thick coat of oil! Should be dry in a couple of days then I can buff the final coat.

 

[OllyK]

A quick bit of google fo woudl suggest that oils like linseed and such like dry by oxidation rather than evapouration. Not quite sure how that works, but oxidation is an exothermic reaction (gives off heat) and so there is the potential for it to generate enough heat to ignite.

 

[White House Workshop]

If that's the case then the fact that my rags aren't screwed up into little balls will allow any heat generated to escape easily. Could be that?

 

[bob_c]

http://wildwoodsurvival.com/survival/fire/spontaneouscombustion/rbjul05/index.html

 

[David C]

Brilliant.

I will now feel much better about delivering the time honoured and oft repeated warning to my students.

David Charlesworth

 

[ProShop]

Bob C,

Excellent find.

\/ \/


..

 

[Shadowfax]

I could not have explained it better than that.
However, if any of you are tempted to ignore the warnings please think again. It can and does happen. I have been involved in the burning buildings that resulted on more than one occasion.
Cheers.

SF

 

[Big Fat Pig]

I used to work in property insurance many moons ago and I too have witnessed the aftermath of oily rags igniting. I seem to recall that rags of an organic nature are more prone to spontaneous combustion than those made of synthetic fibres.
The best combustible rags incident was more petroleum based and far from accidental and the combustion bit was preceeded by a bloody big explosion.And followed by several years at her Majestys pleasure for the Guy Fawkes of Leamington Spa.

Piggy

 

[woodbloke]

Just as a matter of routine and keeping a reasonably tidy 'shop, any rag that's been used for applying a finish is disposed off in the bin outside. I keep a big ice cream tub filled with approx 150mm square bits of rag which seems to last for ages, so that whenever I need a bit of cloth for something it's easy just to get hold of a clean bit...works for me - Rob

 

[TheTiddles]

Not wishing to sound overly pinickety but, IT'S NOT SPONTANEOUS COMBUSTION!

If the tung oil was in the bottle and the cloth was still on the cotton plant, then, it would be spontanous, but it's not, an oxidising agent is distributed across a combustable support with a large surface area in the precense of oxygen. Saying it's spontaneoud combustion is a bit like reffering to the spontaneous combustion of petrol in the presence of a blow torch in an oxygen rich environment

A few years ago there was a lot of research into why some old people were 'spontaneously combusting', it turned out they were all in bed and were smokers, no prizes for guessing what actually happened!

Those little rags with danish oil etc.. on make bloody excellent fire lighters when you return from your workshop of an evening though

rant over, I'll go back to my corner now...

Aidan

 

[bob_c]

I have to disagree, spontaneous combustion is when something ignites without any exterior source of ignition i.e a match,lightning strike ,etc...
I agree that in the case of people lying in bed and it was found to be a discarded cigarette butt isnt spontaneous combustion.

 

[StevieB]

Agree its not spontaneous combustion, but the result of a chemical reaction. Screwing rags up does indeed increase prevent heat escape and allows ignition.

Spontaneous combustion of humans is somewhat different. Experiments with porcine models (don't ask, I spent 3 years researching burns in my younger days) suggests that there is always a source of ignition (usually a cigarette but not always) but in the presence of a low oxygen environment (eg inside clothing next to the skin) which results in a slow burn with high heat that consumes the body/corpse but does not produce a flame with area effect. Hence the pictures of one leg in a pile of ash with no burns to the room attributed to supernatural phenomenon.

Steve.

 

[bob_c]

All combustion is a result of chemical reaction
Therefore the only type of spontaneous combustion possible is as a result of chemical reaction.

 

[Taffy Turner]

Just Googled the definition of spontaneous combustion, and got the following :-

the ignition of fire in an object by internal development of heat without the action of an external agent.

I don't think I can add to that.

Gary

 

[bob_c]

Linseed oil on rags is a very good example of spontaneous combustion,we arent talking about something with a flashpoint of a few degrees,like alcohol or other solvents .Its flashpoint is 222 centigrade.Auto ignition temp is 343 degrees.
It is an exothermic reaction,meaning its actually giving out heat energy.Not taking in in from an external heat source.
Sorry for waffling on!

 

[Big Fat Pig]

Tiddles,if i may say so i think you are being a tad too penickity ( or however you spell it ).Bob C is right in that all combustion involves a chemical reaction. And all combustion involves oxidation.Spontaneous combustion is where a chemical reaction takes place, producing enough heat to eventually ignite without any extraneous source of ignition. ie an exothermic reaction. In fact to take it one step further,when you see flames, it is not the material itself which is `burning` but gasses given off as the material decomposes as a result of heat.
Having typed all that i am now wondering if we are becoming guilty of going down the road of calling a spade a ` solo operator organic/general purpose material inverting implement`.
:?


Piggy

 

[Losos]

Something I was pondering recently is this:-

If I lay my rags out to dry (On the bench say) what is the situation if I wait 'till they are dry (and hard) and then wash then, is it OK to then put the rags in a box all scrumpled up. :?:

 

[bob_c]

They should be safe once dry.Oil takes up oxygen quite fast initially then the uptake of oxygen levels out and the danger of combustion disappears.The oxidation is needed to dry the oil and once dry you couldnt really wash the rags,as oil is not water soluble.

 

[YorkieT]

http://wildwoodsurvival.com/survival/fire/spontaneouscombustion/rbjul05/index.html

Some really good info on theat site Bob :wink:

YorkieT

 

[Losos]

Thanks Bob - Yes, when I apply my limited number of brain cells I realise as you say that a hard dry rag won't wash :lol:

Thanks for explaining that it's the initial phase of drying that's the danger, not after let's say 24 hours when it's like a piece of cardboard and all dried out.

P.S. just had a look at the link as well. Very interesting and no denying the dangers now