Which Primer To Use

[Terry Olson]

Searched, but not finding the specific question I have addressed. I'm repainting my '83 Lund Mr. Pike (aluminum). I bought Valspar polyeurethane enamel topside paint. The Valspar literature calls for an initial coat of vinyl wash metal primer which I gather is sometimes called "metal etching primer", followed by two coats of vinyl zinc chromate primer and two coats of topcoat if painting over all new metal while the vinyl wash metal primer isn't called for if painting over sound previously painted surfaces. I'm leaving some paint on the surface in places where it's sound while taking it down to bare metal where necessary. I'm assuming that I should apply the product as though painting bare aluminum - but the label indicates that the vinyl wash metal primer may lift old paint - DOH! <br /><br />Here's the question:<br /><br />Use both primer products, or just one? In most posts on the subject I only see a mention of the use of zinc chromate primer, then paint. I'm wondering if the other primer product is necessary, advisable, or should be avoided because it may lift old paint etc. <br /><br />Thanks in advance for the benefit of your experience.

 

[Terry Olson]

Re: Which Primer To Use

A few suggestions from posts on other boards although they don't agree with one another - but none from the guys there who paint for a living.<br /><br />I'll probably just go with the zinc chromate primer, then paint.

 

[Paul Moir]

Re: Which Primer To Use

You should do something to prep the aluminium before laying down the primer. Washing the fresly sanded metal with a 50/50 mix of vinegar and water is the poor-man's answer. But the wash primers usually contain chromic acid which not only etches the aluminium but also bonds a chromate coating right to the metal. So this adds another layer of corrosion protection as well as preping the surface by etching.<br /><br />Protecting aluminium in the marine environment is different from what would be done in autobody. There they (normally) use epoxy primers. But those provide no corrosion protection. Be very careful to read and follow the directions on your zinc chromate can (if it really is zinc chromate). It's a known carcinogen. And a real one, not one of those proposition whatever from some state in some country I don't even live in.