finishing cloths/rags

[tusses]

how dangerous are they ?

I read al the time about safe disposal and letting them dry outside etc etc

but how much of a danger do they actually pose ?

I have never heard of any of them catching fire - just that they can !

[jaco]

Pin mine up on a fence next to the workshop to dry.
Cant be too cautious.

The holy old jocks look quite good hanging out ..........
;D ;D

I also spray them with water.
Also have a plastic dish with water for the sponges.

[paulchapman]

They can be very dangerous. I saw some video clips of some convincing experiments on the internet but can't remember where. The fire risks are very real. Take care - a fire can be devastating

Cheers

Paul

[tusses]

I have now seen the internet page - very interesting.

I do treat them with caution - either open them out to dry or chuck them in the log burner.

or , I keep them in a sealed jar ,so they dont dry out, to use again without wasting any.

thats another one I dont need to wonder about now !

[jaco]

Jun 12, 2008 16:14:28 GMT paulchapman said:

but can't remember where.

Cheers

Paul

Yea. well OLD mate, so whats new ...............

;D ;D ;D ;D

[jay]

Linseed oil (and possibly other finishes) generates heat as it cures - which can cause rags to ignite, especially if they're tightly scrunched up (easy to test). It's not difficult to imagine someone scrunching a rag up and tossing it into a waste paper bin or leaving it next to lots of shavings. It's probably the sort of risk assessment that'll have a medium/lowish score on the likelihood of it happening, but be off the dial in terms of potential for terrible disaster if it does.

[tusses]

For those that are interested , this guy did an experiment ...

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

[misterfish]

I must admit that this was a problem that we'd never heard of or thought about.

At our previous house (15 years ago) we'd just had an extension built and floored with terracotta tiles. These were treated and sealed with boiled linseed oil as per the instructions. Anyway, to cut a long story short, we'd applied the last coat to the tiles and grout and then used some kitchen towel to mop up the excess leaving used paper towels screwed up on the floor while we went shopping.

When we got back all seemed OK from outside, but as soon as the door was opened the smoke alarm went off. Against common sense I went to have a look and the new kitchen was filling with white acrid smoke. So I grabbed a couple of bits of hardboard, held my breath, ran into the kitchen and scooped up the smoking kitchen towel between the bits of hardboard and ran through the new conservatory attached to the new kitchen and deposited the tissues and hardboard outside on the patio at which instant it burst into flame!

This was the first time we'd been aware of spontaneous combustion like this and found in very small type on the label (the sort I can no longer read now that my eyes have aged a bit) that materials soaked in boiled linseed oil should be disposed of carefully because of the possibility of spontaneous combustion.

The terracotta tiles where the tissues were left had a permanent dark burnt area that served as a timely reminder. Since then we have always been obsessive about disposal of oil soaked tissues and cloths.

Being trained as scientists, this then 'ignited' our experimental interest and we soaked tissues and rags and placed them in the wood burning stove to see what would happen. We managed to get one test to burst into flames and a couple of times obvious heating and clicking but no combustion. It seemed that tissues and cloths needed to be crumpled loosely to allow enough oxygen access but enough constriction to build up adequate heat to ignite.

Now when we use any of these oil products we are obsessive about how we dispose of the cloths and tissues and always put them in the garden incinerator - I think our subconscious pyromaniac tendencies hoping that they would burst into flame, but no 'luck' so far!

So yes, from our personal experience these materials do pose a danger and you should take care with disposal.

Misterfish

[argus]

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Any material that can oxidise rapidly, such as oils, greases and solvents will generate heat in the presence of oxygen. So it's a precaution we should extend to all flammable materials, not just oils.

If the temperature of the material rises and concentrates sufficiently to exceed the ignition temperature of the host material and favourable combustion conditions exist, it will spontaneously ignite.

This is the reason why oil and grease is strictly prohibited in the presence of oxygen cylinders and on the occasions where oxygen has been use to pressurise vessels containing oil, serious explosions have occurred.

There was an instance of a serious accident in the UK some while back where an oxygen cylinder was confused with CO2 and used for pressurising a refrigeration circuit.

The tins of finishing oils usually carry vague instructions about disposing of rags safely. A tight lidded tin is one good way, as is soaking in water and keeping them in a safe non-combustible space until they are dry.

That said, it's a very rare occurrence, but not one to take risks with.


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