On 12-Nov-2004, (Jacques) wrote:

Yes but gelcoat will not work, it has no wax. What you need is top coat.
Gelcoat is just polyester resin.

For small repairs, you can use gel coat and cover it with release film
until it cures.

Mike

Jacques wrote:
Yes but gelcoat will not work, it has no wax. What you need is top coat.
Gelcoat is just polyester resin.

There's more than one type of gelcoat, specifically there's
"laminating" and "finish" gelcoat. The names accurately describe their
intended function. Laminating gelcoat is used in the mold during the
layup of a hull. Finish gelcoat is used primarily for exterior repairs
and cures properly without needing to be sealed off from the air.

MMC wrote:
Jacques,
My idea is to use West Epoxy with the pigments to fill small chips and
cracks.

That will certainly work, but depending on what epoxy you use, the
resulting patch will be somewhat yellow compared to white gelcoat. You
can use white "finish" gelcoat instead, to get a better match. Here's a
link to it:

http://www.westmarine.com/webapp/wcs...oductId=125479

MMC wrote:
Ah! I see that fiberglasssupply sells epoxy pigments! Thanks for the link!
And good info on the "tile board".
MMC

Pigments for polyester resin work fine with epoxy, too, and are
generally much less expensive.

Brian Nystrom ) writes:
MMC wrote:
Ah! I see that fiberglasssupply sells epoxy pigments! Thanks for the link!
And good info on the "tile board".
MMC

Pigments for polyester resin work fine with epoxy, too, and are
generally much less expensive.

I have some polyester pigmemt the consistency of thick syrup.
I assume it is titanium oxide powder suspended in polyester resin and
would not be suitable for use with epoxy. Does that sound right?
If so you'd have to be careful what kind of pigment to use.
If you buy powdered pigment that should be okay for both?

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On Sun, 14 Nov 2004 15:36:46 -0800, lupi wrote:

I've used Mellomene (melomean? sorry, I canna spell). It's a slick
sort of vynal coated pressboard, fairly expensive, fragile and heavy
to move, used in interior home construction.

====================================

The material you are referring to is "melamine" also known as MDF
(medium density fiberboard). It is readily available at Home Depot in
the US at reasonable prices. It is very stiff and will stay flat if
properly supported.

On 14-Nov-2004, Wayne.B wrote:

The material you are referring to is "melamine" also known as MDF
(medium density fiberboard).

Melamine and MDF at two completely different things. However, some
MDF is covered with melamine. Melamine is a plastic that is used
as a coating on shelving, cabinets and so on.

Mike

to make large smooth fibreglass panels for a boat designed for plywood
construction, boatbuilder TF Jones made the fibreglass panels on sheets of
formica, the stuff used for countertops. fibreglass panels can be made
thin and flexible to bend into a curved shape, then stiffened by adding
more fibreglass.

plastic is a good parting barrier for curing resins. I've put plastic
garbage bags under fibreglass and other resins and adhesives to keep them
from sticking to the work surface. for small jobs you could tape or staple
plastic to any smooth surface, eg plywood. to avoid wrinkles use thicker
plastic. If there is any printing on the plastic it will stick to the
cured resin so put the printed side down.

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William R. Watt wrote:
Brian Nystrom ) writes:

MMC wrote:

Ah! I see that fiberglasssupply sells epoxy pigments! Thanks for the link!
And good info on the "tile board".
MMC

Pigments for polyester resin work fine with epoxy, too, and are
generally much less expensive.


I have some polyester pigmemt the consistency of thick syrup.

Same here.

I assume it is titanium oxide powder suspended in polyester resin and
would not be suitable for use with epoxy. Does that sound right?

The stuff I have does not have the strong styrene smell of polyester
resin. It smells sweet, somewhat similar to latex paint. It was a
fraction of the price of the West Systems tint I bought, which smells
EXACTLY the same. AFAIK, these are universal pigments and work fine with
either type of resin (I'd bet they're exactly the same product).
Although I haven't tried it, I suspect they'll work just fine in paints
and varnishes, too.

If so you'd have to be careful what kind of pigment to use.

It doesn't seem that way, though perhaps there are pigments with
polyester or epoxy bases that would be incompatible with the other. I'd
say "let your nose be your guide".

If you buy powdered pigment that should be okay for both?

Sure. They're just harder to find and I would think more hassle to mix.
I have enough trouble keeping Cabosil in the mixing pot, let alone
adding powdered pigment to the mix. ;-)

Melanie wrote:
My experience with fiberglass is only in basic boat repair. I am a
student of architecture, and I am looking to experiment with the
material's translucent properties for my thesis project. I would like
to make sheets of fiberglass. So I have 2 questions. Firstly, onto
which material could I place the fiberglass (with resin mixture) to
dry without it bonding to it?

I've made panels by placing polyethylene sheet over a flat surface,
laying up the panel, covering with another layer of polyethylene, then
setting plywood and weights on top. Simple, cheap and effective.