I must say that this certainly puts a new light and importance to the issue of
oily rags and letting them lay about. I am not only into cars but also into
woodworking and am guilty as heck of using tung oil, etc.. and then leaving the
rag in a heap or worse yet in a metal trash bucket with other rags. I guess I
have just been lucky up to this point, but this is a practice that I will quit
doing right now.
Now this does bring up the matter of how to dispose of these rags safely.
Jim V.
At 08:51 PM 7/22/98 +0000, you wrote:
>
>Self combustion from "oily rags" is a real threat, but not from petroleum
>soaked
>rags. Oils which can result in spontaneous combustion are linseed and tung
>oils,
>(there may be others, but I do not know of any). The reason that linseed and
>tung
>oils are used on wood (as a finish or combined with dyes as a stain/finish) is
>that
>they polymerize (sp?) in a process combining with oxygen in an exothermic (ie:
>released heat) reaction. So, lets say that you soak a rag with on of these
>oils and
>spread it on some wood, then drop the rag in a heap and go take a lunch break.
> The
>oil on the wood begins combining with oxygen and begins both hardening and
>releasing
>heat. The amount of oil on the surface of the wood is pretty little and the
>surface
>area is large - hence no noticeable rise in the temperature of the wood
>surface and
>no risk. The rag on the floor, however, has a large amount of oil saturating
>it and
>the temperature begans to rise. The speed of chemical reations (like the oil
>combining with oxygen) doubles with every 10 degree F rise in temperature. So
>as the
>rag warms up, the chemical reaction speeds up warming the rag faster and
>faster. If
>the temperature rises high enough one can get smoke and eventually flames.
>There is
>a house not too far from where I live which burned down to the ground a few
>months
>ago from a wood staining rag igniting in the middle of the night.
>
>I am not a chemist either, but I don't think that any oil which is stable in
>air can
>cause spontaneous combustion. If the oil skims over in a can and hardens on
>contact
>with air, be careful. I don't think that common cooking oils are a concern.
>
>-Roger
>
>
<bold><italic><color><param>0000,0000,8080</param><bigger>Jim Van
Hooser
jvanho01@tir.com
</bigger></color></italic></bold>
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