Attempting Spontaneous Combustion

6 months ago, I was talking about the dangers of oil-soaked rags, and bought some linseed oil (raw) to see if I could duplicate some of the ship fires I experienced, where incorrect disposal of linseed oil rags resulted in a spontaneous combustion.

It has taken from until now to actually carry out the first test, so into a wheelbarrow I placed a clean (new) rag, which had been significantly doused in raw linseed oil.  I used a wheelbarrow because it is obviously fire resistant, and means if I needed to, I could wheel it away, or flood it with water (or hit it with the fire extinguisher).

I ran the actual experiment outside for safety reasons again, and it’d be interesting to know if that had an impact on the initial results.

linseed experiment-3

Spontaneous Combustion Experiment

Inside the shed I set up a laptop with some data logging software on it, and had a USB-powered thermocouple inserted into the centre of the rags to monitor the temperature.

linseed experiment-2

Oiled Rags

The rags were quite soaked in the linseed oil, and screwed up like they were carelessly being thrown away.

The Results:

linseed experiment-1

Temperature Range

I set the experiment to run for 10 hours (didn’t think it would need all that, but there you go), and sampling every 30 seconds.  1200 data points in all.  To explain some features of the graph – the first tiny spike was where I tested the ambient temperature.  The test started in the shade around 10:30 am, went through the heat of the day (ambient temperature was around 31 degrees C), and approx 3 hours in, the sun began directly impacting on the experiment (as you can see with the sudden temperature rise).

The temp started around 21 C, and peaked at 61 C, 6 hours into the experiment.  Didn’t think that was too bad a result, but certainly wasn’t the smoldering wreck I was expecting.  I could still pick up a bit of a skin reaction and that fuzzy feeling in the back of the sinuses, so there was some reaction going on, just not as much as I was expecting.

However, there are a number of variables that quite conceivably had an impact on the result.  The linseed oil was raw, and not boiled, the rag was quite thick, and not worn down at all.  The rag was screwed up, but not particularly tightly, and was out in the open rather than in a bin under other objects pushing down on it (increasing the compactness).  It was outside, in direct sunlight (which may have caused some evaporation of the oil, rather than having it remain to slowly combust).

I guess a second test is in order to eliminate some of these variables, and see if we can’t score a result (aka burn baby!)

11 Responses

  1. Stu. I don’t think the hot weather helped. Try Lacquer thinner, in the shade.
    At my paint factory we always laid out a rag flat to dry so it would not combust or at night time we always disposed of all rags to a water bin.
    I know from experience that many customers over the years have had fires resulting in rags with thinners, generally after the workshop is closed at night.

    Cheers, Michael

    • Thanks Michael – I was wondering if that was the case. I’ll definitely have to run another trial during a cooler day (or even at night). I find it quite ironic that the Aussie sun actually helped prevent a fire in this case, rather than contribute!

  2. I always thought that the rags had to be in some sort of container. I wonder if it would make any difference if you had a few rags tossed into a tin can. Something to help hold the heat and fumes.

    Let us know if you manage to burn down you shed Stu. Just kidding of course!

    This is one of those things that I have always thought was a bit of an urban myth but I know better. I’ve just never witnessed it for myself.

    • Tin can isn’t specifically necessary, although it may help accelerate the situation.

      Certainly isn’t an urban myth – it is a real danger, and worth being aware of if you use any thinners/oils with rags and don’t have a procedure in place of disposing of the rags afterwards.

  3. Stu ….. are we now going to see you parading around the shed this coming summer in a sleeveless flannel shirt?

    Stinky.

  4. Stu…when you try again mix some driers with the oil. The driers accelerate the oxidation (drying) of the oil and the temperature goes up quite considerably.
    I used to demonstrate this when I taught Painting & Decorating at Polytech years ago.
    The drier you can use is sold as Terebine and should be available at a good paint store.

  5. Great experiment Stu. I am really looking forward to seeing what it takes to create a fire with rags/oil/thinners, etc.

    For our own workshop, at the end of the day we soak all oily rags in water. So once you create the fire scenario, I would be interested in an extension to the experiment by soaking them in water and measuring that outcome. If you care to go that far that is.

    • More investigations required definitely – slowing down the process seems one that will potential add to a possible result, and using boiled (or otherwise thinned) oil.

      Still, the temperature did reach double that of ambient, so if it had been able to continue to build, a result would have been achieved, so it is very likely I will be able to nail down the variables.

  6. […] looking through some files taken off one of the cameras, and found this video shot as part of the Linseed Oil Experiment.  Better late than […]

  7. Lavington pizza shop burnt
    07 Jan, 2011 01:00 AM
    SPONTANEOUSLY combusting tea towels have sparked a fire that will put Paddy’s Pizzaria out of action for weeks.
    Tea towels that had been used to clean up spilt vegetable oil, washed, put in the dryer and then stored, sparked the blaze.Because of the heat from the dryer and the oil that was still in them they combusted and basically burnt the whole kitchen out.

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