Painting on galvanized sheet metal

The problem here is the type of paint that you are using. The oil based paint will react with the zinc coating regardless of how you prepare the metal. I suggest you change to an acrylic latex paint which can go directly on the galvanized surface after it is cleaned and polished with 0000 steel wool. A water-based lacquer will protect the finished product.

My wife is also an artist in metal. After years of testing and research, we found that oil based products will at the least yellow the product in a few months.

Paints made for galvanized metals are generally very high in their solids content and therefore will opaque out the speckled nature of the galvanized surface. I would suggest that you clean the surface with lacquer thinner, then apply clear shellac as a primer. Don't spray or brush it on, rub it on like you would do a French polish. Then lightly sand the surface with very fine paper, 600 grit or finer and apply a second coat by spraying. Do your air brushing, then follow with a clear coat of acrylic enamel. Hope this helps.

Do you have a local galvanizing plant?

My galv. plant has a branch that does anodizing in many colours and I would think this may be your best bet.

Galvanized sheet metal will adhere paint if aged/weathered. This can be artifically done (and is done in the exterior painter's field) by wiping with vinegar and rinsing. Try that on test spots to see how well "pattern" is preserved for air brush application.

Galvy:

Try wiping it down with either muratic acid or vinegar. I have a friend who does a lot of galvanized work, and he swears the problem is not the surface coating but the lubes used during the process. He says he uses one of the above, or uses an acid based solder flux. Hope that is a help.

mastrsmth

As suggested by Mstrsmith (#5), etch prime with dilute muriatic acid.

For a finish coat, epoxy sticks well. Note that if exposed to strong sunlight, epoxy eventually chalks and slowly flakes off.

If using indoors, it should last for years.

The acid etch will probably accentuate the crystals which give you the speckled effect.

Could epoxy paint be applied airbrush?

"Could epoxy paint be applied airbrush?"

Yes. In a hot climate (35-40C ambient) pot life can be short but in most climates spray application is no problem.

No one mentioned Zinc Chromate primer. Do they still make the stuff?

Bill

Sure they do. However, this fellow needs a transparent primer/binder to form a base coat for air brush decoration of the galvanized sheet metal (steel).

Exactly!

And during prep he does not want to etch away totally the "sticks and shadows" galvanic dipping patterns on the new metal. All the solutions (pun intended) that are mentioned above (or could be mentioned) are essentially artificial "weathering" processes.

It will no doubt occur to the artist (if it has not already) that test-trails will need to be done (to ensure real-trial preservation of desired "canvas" properties); and that the experimentation leading to a rule-of-thumb formulation needs to proceed, stepwise, from less reactive (i.e., less "effective") to more reactive &or from more dilute to less dilute, as well as from less costly to more costly, in terms of "weathering solution" choices. (It will be the reverse of the engineer's or DIYer's natural bent of mind.)

On the one hand: whether or not a primer or base coat (i.e., under coat) is essential is not arguable...and any paint can be its own primer if adhesion tested and proven. (After all, primers are paint, too.)

On the other hand: the novel idea of a transparent, "micro-tacky" sub coat is a good one, especially for airbrush ... provided that the transparency property is not (rapidly) altered over time (or is gracefully altered "artistically") by locally occurring light &or atmospheric aerosols. Since it is metal art, that last part is, quite likely, favorably left to time and chance.

Hi all,

Thanks for the much needed and informative feedback regarding my situation.

I have also heard that the processing lubricants in the galvanized metal are a main deterrent in paint adhering to this metal (as mastrsmith noted). I am presently conducting a few test pieces to see how the paint stands up using the steel wool to prepare the surface followed by a vinegar solution wash.

As I stated previously, the pieces will be an indoor item and not subjected to weather elements except of course present indoor humidity levels and possible periodic direct sunlight indoors through a window.

I have done much research and development with my work and this is the final leg of the program and I really apreciate everyones input.

The gentleman from Scotland who suggested the anodizing got me thinking. That would be a really excellent finish, but I had done some research earlier, as I also had this idea, but I was under the impression that it could only be applied to aluminum, unless of course I missed something somewhere.

I will try a few of the suggestions from above and will post my results at a later time.

Thanks to all....