RCM only

On Mon, 31 Aug 2009 21:58:24 -0700, the infamous DaveC
scrawled the following:

The goal: to change the color of a few new, factory-painted steel parts. I
lightly sanded all surfaces with 800g emery paper. Cleaned up with denatured
alcohol. Sun dried.

First coat of spray enamel went on and dried to a fine gloss finish. Dried
overnight inside and put outside again in the sun while I was at work for a
thorough drying.

Came home, lightly sanded again, cleaned with d.a., dried, and sprayed a
second coat.

Almost immediately (less than 10 seconds) the coat took on a curdled look.
Sort of wrinkled. Not "orange peel", but it looks like the cracks in a dried
lakebed. This effect was apparent on all parts I sprayed with a 2nd coat, not
just one.

What did I do wrong?

Obviously I'll have to dry it, sand down to the original finish and do it all
again.

What should I do differently?

Paint is Rustoleum "industrial strength" enamel.

I wouldn't sun-dry anything metal and I wouldn't use the alcohol
between coats. I think the alcohol was your most likely culprit
unless you sprayed HOT parts, right from the sun.

--
Good intentions will always be pleaded for every assumption of authority.
It is hardly too strong to say that the Constitution was made to guard
the people against the dangers of good intentions. There are men in all
ages who mean to govern well, but they mean to govern. They promise to
be good masters, but they mean to be masters. --Daniel Webster

I wouldn't sun-dry anything metal and I wouldn't use the alcohol
between coats. I think the alcohol was your most likely culprit
unless you sprayed HOT parts, right from the sun.

Hmmm. I almost always use alcohol between coats. VBG Normally a 12 oz. or
two. Sometimes a little shot.

Karl

"Larry Jaques" wrote in message
news
RCM only

On Mon, 31 Aug 2009 21:58:24 -0700, the infamous DaveC
scrawled the following:

The goal: to change the color of a few new, factory-painted steel parts. I
lightly sanded all surfaces with 800g emery paper. Cleaned up with
denatured
alcohol. Sun dried.

First coat of spray enamel went on and dried to a fine gloss finish. Dried
overnight inside and put outside again in the sun while I was at work for
a
thorough drying.

Came home, lightly sanded again, cleaned with d.a., dried, and sprayed a
second coat.

Almost immediately (less than 10 seconds) the coat took on a curdled look.
Sort of wrinkled. Not "orange peel", but it looks like the cracks in a
dried
lakebed. This effect was apparent on all parts I sprayed with a 2nd coat,
not
just one.

What did I do wrong?

Obviously I'll have to dry it, sand down to the original finish and do it
all
again.

What should I do differently?

Paint is Rustoleum "industrial strength" enamel.

I wouldn't sun-dry anything metal and I wouldn't use the alcohol
between coats. I think the alcohol was your most likely culprit
unless you sprayed HOT parts, right from the sun.

--
Good intentions will always be pleaded for every assumption of authority.
It is hardly too strong to say that the Constitution was made to guard
the people against the dangers of good intentions. There are men in all
ages who mean to govern well, but they mean to govern. They promise to
be good masters, but they mean to be masters. --Daniel Webster

I skipped over most of this thread but someone explained that real enamel
has a narrow window for re-coating, and that it will wrinkle if you miss the
window. Rust-O-Leum itself points out that the re-coat window varies
*widely* on their different products. They have a lot of information on
their website.

Most of their heavy-duty enamels are alkyds and modified alkyds, and some of
them are very slow driers. But they'll develop a skin very quickly. When the
OP mentioned that he sanded between coats my first thought was that he had
one of the quick-drying ones, but then I remembered that their paints can
develop quite a thick skin and still not be cured enough to re-paint.

I did one job (but with their fish-oil paint, 45 years ago) that wrinkled,
and then the top coat peeled right off like a sheet of Saran wrap. g

--
Ed Huntress

I skipped over most of this thread but someone explained that real enamel
has a narrow window for re-coating, and that it will wrinkle if you miss the
window. Rust-O-Leum itself points out that the re-coat window varies
*widely* on their different products. They have a lot of information on
their website.

From the Rustoleum site:
"
Strong solvents can also soften a previous finish and make your new paint
application susceptible to wrinkling.
"
and
"
If you sand in-between coats, allow the full recoat time to dry before
applying another coat (at recommended drying temperature).
"

So I guess sanding after 24 hours exposed not-yet-dried paint and the alcohol
softened it further.

So recoat within 1 hour or wait 48 (as the can says...).

Thanks to all who contributed to my education. :-)