The American Galvanizers Association has an excellent --FREE--
publication titled "Painting Galvanized Structural Steel." You can
obtain a copy by calling them at (303)750-2900, by filling out the
form on their WWW site at http://usalink.net/aga or by sending them an
e-mail at email@example.com
As with any painting task, the job can be done easily and reliably if you
prepare yourself with knowledge and follow manufacturers recommendations!
Proper surface preparation is extremely important! The surface must NOT
be perfectly smooth and it must be clean and completely free of oil,
grease, dirt, etc. Wire brushing, cleaning with detergents or solvents as
needed, and rinsing with clean water should do the job. Optimal surface
preparation depends on the actual condition of the zinc surface, and
excellent recommendations are provided in the AGA brochure.
Select the correct primer -- the primer must be compatible with the
metalurgy of your zinc surface. Zinc dust/zinc oxide primers -- also
known as metallic zinc paints -- are the best choice for most
applications. Such paints typically have 80% zinc dust and 20% zinc oxide
and meet Federal Spec TT-P-641 -- Type I for rusted surfaces and Type II
for galvanized surfaces that are not rusted.
Fed Spec TT-P-641 paint is available from McMaster-Carr Supply Company, in
a 16 oz. spray can (catalog # 7725T3 $6.35 ea), in quart cans (# 7725T2
$22.92) or in gallon cans (# 7725T1 $83.33). You can order from
McMaster-Carr with a credit card at (908)329-3200 (M-F 0700-2100 Eastern
Time). They typically ship same day from stock. I have also used
Rust-oleum acrylic paint products designed specifically for use on
galvanized surfaces with good success, although the paint referenced above
is probably the best overall choice.
The top coat must be compatible with the primer. A second coat of Fed
Spec TT-P-641 primer is probably the best topcoat if its metallic gray
color is acceptable. Be sure to follow manufacturers recommendations in
choosing any topcoat.
Be sure you apply the paint properly to the surface -- too thick is not
good! If you need a thick coating, apply several coats. In any case,
follow manufacturers recommendations. Don't paint before (or during) a
rainstorm, or when dramatic temperature swings are expected during the
curing time of the paint.
> On Mon, 16 Sep 1996, Leikhim, Joe wrote:
> I am looking for a good epoxy primer to apply to galvanized metal prior
> to painting with epoxy paint. I tried some epoxy pool primer and found
> it all just peeled right off despite prepping the metal with TSP and
> mineral spirits. Any thoughts?
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