Dave,
In response to your question about paints,
It is my understanding that paint is basically some solid stuff
dissolved in some liquid.
"Back again. A more complete description about the marine paint in
question. The paint is described in my catolog as a TOPSIDE paint.
Chemically the paint is an enamel with a blend of urethane, silicone and
alkyd. Being chemically challenged, I don't have a clue what these
components should do in the making of paint. Would paint made with
these
components breath?"
Alkyd implies that the liquid is organic and that means that you have to
wash your brushes in turpentine or kerosene. The water-based version is
latex.
Urethane implies that the solid will polymerize on drying to form
polyurethanes (that's why you should avoid getting dust into urethanes,
because that hastens polymerization and that's why "old" urethane paints
get thick with time). As far as I know, these are also only oil-based.
Silicones consist of structures that contain silicon (obviously) and
this element behaves a bit like carbon and can form complex chemical
structures.
All of them together, when dry, would form a pretty waterproof barrier,
I would think and I doubt if it would breathe at all.
"Alan Alderwick describes the type of paint that causes cocooning (
preventing breathing ) in wood as BITUMASTIC. This must be an English
term
because I could not find it in The New American Webster Dictionary. Is
anyone out there familia with bitumastic type paint? Chemically how
closely does bitumastic paints relate to the paint described in the
first
paragraph?"
I've never heard of "bitumastic" either. Reminds me of "tar and
feathering." Looks like the word was coined to imply that it behaves
like bitumen which would hardly allow breathing.
Note that John Blair has suggested the West Epoxy method. Epoxy is also
a polymerizing material and would not be expected to breathe.
Have you considered having the wood pressure treated with a wood
preservative prior to sealing the surface? I believe that what Morgan
is finally doing to their wooden frames.
Unless you live in a very damp climate or submerge your Morgan
occasionally, I would imagine that sealing the surface of the wood
should be OK. The trick is to seal the complete surface. Note the
comment by John Blair: "I used West System Epoxy on my wood. I had the
entire tub taken apart and painted each piece with the epoxy, sanded it,
and applied a 2nd coat." I take this to mean that you have to be sure
that the ends of each piece of wood is sealed, and that you not just
coat the joints and leave the but ends of the pieces uncoated.
My choice, if it were possible, would be to impregnate the wooden frame
with a low viscosity monomer and then polymerize it using an ion beam,
sort of applying high tech solutions to old-fashioned automotive
fabrication methods.
Maybe somebody can offer some advise on the desirability of using a wood
preservative. Will epoxy paints adhere to the surface afterwards? Has
anybody asked the Morgan people?
Good luck.
Chuck Vandergraaf
'52 +4
Pinawa, Manitoba, Canada
vandergraaft@aecl.ca
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