Stan,
Unfortunately, while your Dad's trick undoubtably did work, vinegar is an
acid that also took away some of the remaining life of the galvanized
surface!
Modern painting systems allow galvanized metals to last indefinitely, even
if they have begun to deteriorate; however, it important to prepare the
galvanized surface properly AND to use an appropriate primer. Current
practice is very thoroughly described in the FREE American Galvanizers
Association (AGA) publication "Painting Galvanized Structural Steel,"
available by calling them at (303)750-2900.
Quoting page 16 of that publication: "In the past, galvanized steel was
often cleaned with vinegar or other mild acid prior to painting. This
practice is no longer recommended. Instead, solvents and detergents
should be used which effectively clean but are less agressive to the zinc
surface."
The AGA recommends cleaning with detergents or solvents to remove loose
rust, dirt, oil, grease, etc, then rinsing with water. Federal
Spec TT-P-641B primer for galvanized steel is readily available from
McMaster-Carr and Rust-Oleum also has appropriate primers.
> On Sat, 21 Sep 1996, Stan Griffiths wrote:
> My Dad, W7PH, and OLD painter, taught me a painter's trick for painting on
> new glavanizing to keep the paint from peeling. Paint it first with
> vinegar. Apparently, the acetic acid in the vinegar reacts with the zinc in
> some way that makes a surfce the paint will stick on much better. We used
> to do this all the time on new construction when we had to paint new
> galvaized gutters. The frustrating part of it is that you can't SEE that
> you have done anything. It's a lot of work and nothing looks any different
>
> Stan w7ni@teleport.com
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