Message-ID: <001d01c099d4$1d969c20$f4b088ce@pavilion>
From: "J. N. Cameron" <toucan@The-I.net>
To: "Lancair List" <lancair.list@olsusa.com>
Subject: Shrinkage of UV Smooth Prime
Date: Sun, 18 Feb 2001 11:56:11 -0600
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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In response to Marv's question of how do I know my UV Smooth Prime is still
shrinking:

    What I did was to prime some parts and leave them for at least a month.
Then I applied a guide coat and wet-sanded till the guide coat was all gone,
leaving a flat, smooth surface.  If you wet that surface and looked hard in
all angles of light, it was smooth as a mirror.  Then I waited another
couple of months, applied more guide coat (either the spray lacquer kind or
the newer, dry stuff from 3M), and started lightly sanding with 600 or
higher.  The underlying weave pattern immediately became visible, which
indicates that the paint had continued to shrink down into the weave between
the first and second sandings, which were some months apart.

    On some parts I also applied the water-based top coat, after at least
one, and in some cases two bouts of guide coat plus wet-sanding.  Then I did
the same thing with the top coat; i.e., I waited at least a month, and in a
couple of cases several months, applied guide coat to the top coat, and
wet-sanded that, starting with either 1000- or 1500-grit 3M Wet-or-Dry.
Again, the underlying weave pattern was immediately obvious.  After sanding
it completely flat, to a mirror-like surface, I buffed with Finesse-It II.
(Which, BTW, produces a final gloss that is IMHO not nearly as good as the
stinky polyurethanes.)  After a few weeks, in the right light you can again
see the underlying weave, now coming through 6+ coats of primer and 3+ coats
of the top coat!  If this doesn't represent continued shrinkage of the
paint, I don't know what else could account for it.

    As for application, I used a sponge roller for the first three coats of
the UV Smooth Prime, then sprayed the next three.  On some parts I had to
spray another 1 to 3 coats to really get the weave filled and a
smooth-sanded surface.

    I hate to keep bad-mouthing the stuff, since I've put most of this on
LML before, but questions keep popping up from various builders, so . . . .
Some final bits of information:  This paint system ends up being fairly
expensive, since quite a few more coats are required than with other paint
systems.  Poly-Fiber refunded all the money I had spent on it, along with a
letter acknowledging that "some builders" had experienced problems.  I am
still debating whether I will need to sand it all the way back to the
e-glass, or whether I can leave some of the Smooth Prime underneath as a
first primer coat (with Corlar or DP-40 over that).  I'm worried that even
the amounts that are left in the pits of the weave will keep shrinking over
time, giving my Imron a "weavey" look.  Aaarrrggghhh!

Jim Cameron, ES builder


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