On Thu, 25 Mar 2010 11:04:49 -0400, I am Tosk
wrote:

In article ,
says...

On Wed, 24 Mar 2010 20:20:45 -0700 (PDT), Frogwatch
wrote:

Say you want to drive the moisture out of gelcoat. I've used a heat
gun to do it and was surprised at how much water came out.
So, what would a high power microwave unit do? Water absorbs the
microwaves much better than the polyester so it would get hot and come
out. This would avoid the months of waiting for a hull to dry if you
are repairing blisters (a real scam as blisters are not a real
problem).


Some years ago I read, in one of the boating magazines, about a guy
that had invented an innovative method of drying a hull. He removed
the door from a micro-wave oven and bypassed the "door-open" safety
switch. Placed the oven face down on the deck and turned on the power.

I never read anything more about the method and have visions of him
heating the saturated deck core to the point that steam was generated
and the resultant upheaval.

Water when heated turns to steam and I can assure you that the steam
will come out :-)

Cheers,

Bruce

Won't vacuum boil out water vapor?

Scotty

Well, yes I suppose that you are correct in that a decrease in
pressure results in water vaporizing at a lower temperature, however
suspect that the evaporated vapor has far less energy then water vapor
that is produced by heating. At least it is difficult to put a pot of
water out in the sun and power a steam engine with it :-)

I suspect that the O.P. was trying to devise a method to laminate
layers and get a chemical bond between layers. In practice no one who
works in the trade seems to consider this a problem. The worry about
laminating epoxy structures is always amine blush and cleaning it
prior to laminating the next layer.

There are epoxies that do not produce blush but I have never seen them
used in actual practice. I suspect it is a matter of cost.

It would be interesting to see some testing of laminated structures
produced by continuous laminating, I.e., not letting the epoxy set up
between layers, and the same structure produced by waiting until each
lamination hardened and then sanding with coarse paper before applying
the next layer.

Cheers,

Bruce