painting galvanized

[shadetree]

This is a little off topic, but does anyone know the straight story on painting over galvanized? I have a bunch of square tubing that I want to make a gate out of, then paint it black. One buddy says I'm spitting in the wind to paint over galvanized, another says to wipe it with vinegar first and the paint will hold. I'm looking for some more opinions.

Thanks.

[Franz]

Acid treating (vinegar) seems to help a lot. It also helps if the galvanize is aged as opposed to new.
If memory serves, zink chromate primer is supposedly the bonding agent of choice.

[cope]

Re: painting galvanized

Originally posted by shadetree
This is a little off topic, but does anyone know the straight story on painting over galvanized? I have a bunch of square tubing that I want to make a gate out of, then paint it black. One buddy says I'm spitting in the wind to paint over galvanized, another says to wipe it with vinegar first and the paint will hold. I'm looking for some more opinions.

Thanks.

Sears used to sell a product called Cold Grip, or something like that. I brushed it onto galvanized steel gutters and brushed on Latex enamel, and it held until the gutter rusted from the inside out. It looked like thick shellac.

[HELLTACO]

Juse a lil' sandpaper wit dat vinager. Don't worrys abouts da galv goin' away, cuz dat jus don't happin'.

[Snidley]

You can get primer for galvanized metal. With the vinegar wash and the primer, all you will do is extend the length of time before the peeling starts.

[Ben]

I have had experience with galvanized over the years (roof valleys, etc.), and the only sure way that I have found is to let it age in the elements. For some reason, Mother Nature seems to be the only cure. If you can, wait over a year, otherwise it may start peeling on you. I am unaware of any other adhesion agents out there, but check with a local paint store - you may get lucky.

[Suburban_Guy]

I just had a quick look in my Ditzler manual and their DP40 Epoxy primer and Kondar DZ primer-surfacers are both rated for properly cleaned and treated galvanized surfaces. Most other primer products are not recommended and definately not any topcoats without a suitable primer underneath. The Kondar is a lacquer primer that can be used without expensive supplied air respirators but it must be sanded before topcoating.

Harley

[Roger]

Isn't alot of auto bodies galvanized these days? Any automotive paint store should have a primer or 2 that will work.

[JTMcCracken]

About 5 years ago we made close to 350 welds on galvinized 2 1/2" & 3" pipe for an ADOT job and they called for 3 coats of a very expensive industrial paint. I subbed out the paint but I probably have the paperwork around here someplace. If I get a chance I'll see if I can find it and let you know what the Arizona Dept. of Transportation considers the proper spec for painting galvanized. The paint spec's were very detailed and very specific as I recall.

JTMcC.