I've been asked to paint a sign for a local business, it's galvanized... does anyone have any experience with trying to paint this stuff. I've looked all over the internet and found everything from white vinegar to acid etch to prep it for paint. I explained to the customer that it was notorious for not holding paint, but since it had been painted before, he thinks it'll be o.k.. He wants me to use all automotive products, so that it can be clearcoated when finished... I don't want to put my name on something that's gonna delaminate in a couple years. Any advice would be great.
Since my job is painter and decorator, I've had to paint a load of galvanised metal in my time, the problem is the most commonly used used primer was "calcium plumb-ate", this was assuming it would be painted afterwards with ordinary household undercoat and gloss finish, the stuff remains soft even after drying, but due to leaded paint regulations you won't find this any more. For your purpose the best primer will, if you can find it, is "Etching primer" this dries hard and is ideal automotive work since we used it if it had to be followed by cellulose based paints, it dries rock hard and holds good to the the metal. If you can't find this there are several good multi primers available, although I don't know any of the manufacturers in your neighbourhood, any good decorators shop will help you find the right product, just be sure that whatever you choose that comes from trusted named company, you will know if the primer is any good, for you purpose prime 3 days before further handling, if its an old panel and the paint is flaking, this will be due to oxidisation of the zinc in galvanised mix, you must clean everything off and if sanding do not go through the galvanised film. You can sometimes use aluminium primers but they will not suit your purpose since they also remain relatively soft. Hope this helps.
I did it once, a little sign for a friend, and it held up ok, but it was only about a year ago, so don't know how it will hold up after "years", but so far so good.
Thanks Mb, the owner and I were thinking about sand blasting the whole thing, but if you say not to go through the zinc... maybe not. And yeah, I can get etch primer. It seems like the best way to go, I have automotive spray guns to do it with. I'll just treat it like a panel of a car. I can etch prime, urethane primer, urethane base, artwork, and clear. The only problem will be the size, it's 4m x 6m. Squishy, what kind of paint did you use on the one you did?
Is that for etch prime or the multi prime? Or is it the galvanized that needs the time? I'm in uncharted waters with this. Once vinegar and the three phases of zinc oxidation popped up in my internet searching, I new I was lost. Sounds about like what I'll end up doing doing. Other than solvent based for the artwork, that's the plan. How was the etch primer to use for you guys? Is it sand-able and spray o.k. and all that? If it's a good enough primer, i may just do what you did Squishy, and put the base coat over it and skip all the sanding of the extra coats of 2k primer. I'll end up doing a test spray of all the steps I plan to use either way, I can try it both ways and see. Thanks for the help you guys... I was going in blind.
