Date:         Thu, 7 Sep 1995 13:09:56 -0500 (CDT)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Gerald Skerbitz <gsker@lenti>
Subject:      Re: Even More White Discussion

The message is included below:
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>From ja@coe.wvu.edu  Wed Sep  6 19:58:34 1995
>From: John Anderson <ja@coe.wvu.edu>
>Subject: Re: Even More White Discussion
>Date: Wed, 6 Sep 95 20:46:43 EDT

Rusty,

gel coat is done in two major ways from my knowledge, first of all
FWIW it is a layer of basically resin only that is on the surface only
of a fiberglass layup, either hand laid or spread by spray chop gun,
now I'm more into testing myself not production techniques but I have
read on the subject, it is done in a couplle of ways, first one is the
gell coat resin is put down in the mold, before the fiberglass and to
keep the fiberglass from settling through it's resin is either denser
through the addition of powderred fillers (usually clay) and also
possibly dyes to add color, or it is a special resin that sets up but
does not fully cure until removed from the presence of O2 such that when
it is trapped between the mold and the next layer containing cloth, it
cures.  The other technigue is to spray the coating of primarily resin
onto the finished product, similarly it might be fortified with fillers for
opacity and dyes for color.  This is the method used to repair I
believe.  The best place to check on such info is you local boat shop,
who repairs aged fiberglass all the time.  The only problem, which is
what we experience is that polyester, vinylester, and epoxy resins are
notorious for breaking down under UV radiation.  I mean hell the '77 we
just bought for my parents has been garaged its entire life, paint is
like new but the gel coat is leaving fast and only left on edges, which
by the way means VW probably used the first technique whereby the gell
coat was down in the mold first, hence on edges and corners, the resin
pooled but the fiberglass wasn't well shoved into the nooks and crannies
so more resin was there and more remains.  Now VW may not have even let
the stuff set up or anything and simply probably sprayed a heavy layer
of resin, followed by the glass since I personally don't think the gell
coat was ever thick over main flat areas.  If I really wanted to restore
one to "perfection" or as close as one could get, my techniqe would be
to buy catalyzed polyester primer surfacer, this is a primer
surfacer you add a hardener to then spray with a gun and it becomes
essentially sprayable body filler, great stuff for body work as well.
Goes on thicker than laquere based primer surfacer and DOES NOT SHRINK.
After meticulous surface prep, X19 for mildew, then bleach water, then
paint degreaser, then sanding 220 or so, I'd lay down a couple of major
layers of that stuff then top coat with your white choice of hardened
acryllic enamel or urethane.  Personally for the '78 whose top is crap
and who will never be concours I'm going with Martha's RV roof sealant
solution, for the '77 I may eventually go the better route.

John
ja@coe.wvu.edu

BTW, most all hand laid fiberglass, particularly that made in a press
takes on a perfectly smooth coat from the resin running out to the
surface, though the resin will not be thick over the fibers.