Date: Thu, 6 Jan 2000 08:36:22 -0700
Reply-To: "Michael A. Radtke" <m.radtke@ELM.AZ05.BULL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Michael A. Radtke" <m.radtke@ELM.AZ05.BULL.COM>
Subject: Vanagon, Paint, and Isocyanates
Hello,
Painting your Vanagon comes up on this list from time to time. I am in the
middle of a couple of restoration projects, so I have been researching this
subject for 18 months. I don't have the answer:
1) Lacquer is easy to apply, has no isocyanates, but dumps lots
of solvents into the air. Lacquer cures through evaporation
of its solvents. I have a 10 year old professional lacquer
repair on my Vanagon. The color still matches perfectly, but
the surface has crazed.
2) Acrylic enamel does not need hardener. Acrylic enamel initially
dries by evaporation of the solvents, but then cures over many
months by oxidation. It is quite delicate for the first week
or two. Baking can be used to speed the oxidation process.
An isocyanate hardener is almost always added to acrylic
enamels these days. The real purpose of the hardener is to
catalyze the oxidation process so it completes in hours rather
than months. That's why it's sometimes called a catalyst.
A side effect of using a catalyst with acrylic enamel is that
the rapid curing makes the paint harder. That's why the catalyst
is sometimes called a hardener.
Old non-catalyzed acrylic enamel tends to be just a bit rubbery.
It can be scratched more easily than catalyzed acrylic enamel.
But, scratching catalyzed acrylic enamel may result in chipping
and flaking because of its greater hardness.
3) Polyurethane auto paint is always catalyzed. It is more rubbery
like non-catalyzed enamel, but is tougher (not harder).
4) Isocyanates have been linked to about every type of disease.
The most common problem is some chronic breathing problem such
as asthma. Just don't ever use an isocyanate hardener with out
a positive pressure fresh air breathing apparatus.
5) Polyurethanes can be cured (cross linked) with non-isocyanate
catalysts. Some polyurethanes cure with water. However, no
one seems to make a polyurethane paint that uses a safe cure
for automotive applications. The closest that I've come is
Polyfiber's Top Gloss (http://www.polyfiber.com). This is an
aircraft paint designed specifically for the DIY market. While
it appears to be safe enough, their web site claims "dries to a
high-gloss, wet-look finish." However when you buy the paint
the instruction book says that you can't even hand buff it to
a gloss, but rather must use a power buffer. Thus, I haven't
even tried to paint with it.
So, what have I learned? Do all the prep myself and let the
professional do the painting.
Mike '84 GL '60 Vespa '58 Isetta --- Phoenix, AZ