Crossposted to sci.chem.coatings where maybe there is someone who
will know the answer.

Tim Douglass wrote:
On Thu, 04 Aug 2005 19:19:51 -0400, JoeTaxpayer
wrote:

...
I understand the solvent soaked rag issue, I leave those out in the yard
to dry and throw out. ...

OIL soaked rags, in particular boiled linseed oil and tung oil or
opther _drying_ oils, that is those that react with oxygen and
polimerize as a serious spontaneous combustion hazard as the
process is exothermic and the material is combustible. Solvent-
soaked rags should also not be kept indoors (for the most part,
not _used_ indoors either) both because of the danger of developing
an explosive atmosphere and for to minimise exposure.


Shellac is a natural, organic product. It is quite possible that if it
was a partial can there had been some contamination introduced at some
point that allowed bacteria to grow and eventually produce the
pressure and explosion. About the only thing I can think of.

I thought of that too, but the bacteria in question would have to
survive in a mixture with a high concentration of alcohol. There
are bacteria that do that, they can even contaminate the alcohol
used in hospitals.

Alcohol is an organic base, shellac an organic acid the reason
pre-mixed shellac has a short shelf life is that they react,
degrading the shellac. I think this is the process known as
'aponification'. Does that produce gas?

--

FF