On Apr 11, 1:35*pm, "N_Cook" wrote:

So wood pulp filler could lead to expansion but if a mineral was used ,as a
filler, *then dimensionally stable bakelite would result ?

Not pulp - well, OK... derived from pulp but not the same. The wood
flour that is used is very nearly pure lignin - that part of wood that
lends strength and is also hydrophobic - so that big oak tree out
there does not dissolve in the rain.

So, to the extent that the wood flour used is contaminated with other
wood components, it might expand when exposed to moisture. But the
material is heated (twice) and formed under great pressure. Most of
the water created by the initial chemical reaction is dissipated in
first heating, the last done under great pressure and greater heat
completes the thermosetting process - but most of the water is already
long-gone. And any non-lignin components remaining were mostly burnt
off in the first go as well.

The smelly plastic is Cellulose Acetate - which goes to vinegar and a
few other smellies. And there are several other materials that use
Cellulose Acetate in their formulations to a greater or lesser extent
- which decay similarly with similar smells.

Peter Wieck
Melrose Park, PA