My dad was cleaning out the attic of the garage recently and found this Aero Klad zinc chromate primer along with some Imron so he brough it over thinking I could use it. It has been there at least 40 years. I'm not a painter so I'm wondering if it is useful or should it just be recycled? I appreciate any insight! Mick
That stuff is especially formulated for the Aircraft industry as a primer for aluminum and magnesium, but it works just as well on steel too. Although after 40 years I wouldn't trust it. Ralphie
Back in the mid 60s i worked at Erie Proving Grounds rehabing Herculese & Ajacks missles. We sprayed the interior of nose cones with Z C....no mask...no wonder i have sinus trouble. Get rid of it for sure. Bugguts has it...keep the can. When was the last time you saw one ?
If they haven't been opened and exposed to air, I'd shake and stir the hell out of them and use them. Then put the empty can on the shelf.
Zinc Chromate was used extensively for aircraft/aerospace applications to prevent corrosion mostly on aluminum and magnesium although sometimes on ferrous alloys. The color was typically yellow although sometimes tinted to a yellowish green. It was highly effective in preventing corrosion but also effective in preventing organic growth such as molds. Unfortunately the hexavalent chromium contained in the primer is a carsinogen. It’s pretty much been banned by various organizations such as OHSA, EPA, etc. or has very strict requirements for use and safety. There are numerous substitutes still listed as Zinc Chromate but they contain little or no hexavalent chromium. If you want to keep the can I would just leave it sealed unless it has been opened before.
I agree, if it is unopened and is still liquid, just mix it well so all of the solids that may have settled out are put back into suspension. No real reason it can't be used, although you may not want to do on something that would be difficult to redo, just in case. It was used a lot in aerospace, over anodized (but unsealed) aluminum to provide good corrosion resistance under the topcoat. The anodizing was to aid adhesion. The active ingredient part is the hexavalent chromium, which is also on the carcinogen list. It will work on steel. Just wear proper PPE so you are not breathing in the vapors when painting or a lot of sanding. For that matter Imron is also bad for you, so same cautions. Imron has isocyanates as the bad for you part.
The old Zinc Chromate has been pulled off the market because it has hexavalent chromium. They still sell it, but it has been reformulated to be more environmentally friendly. It's usually only an issue when sanded. Sort of like asbestos. We just spent close to a million bucks cleaning our hangars.
The old stuff is the "good" stuff; I know cause I've stripped a lot of it over the last 35 years. If you have any aluminum to paint I'd use it (taking proper precautions) and then save the can. You can't get it anymore and the newer stuff doesn't work nearly as well.
Back in the early 80s, my dad and I stripped/prepped/ repainted a couple of early 70s Freightliner trucks. They had a light green primer on the aluminum. Would that have been about the same stuff?
Most likely. Carbon black and a chromium pigment (green) was sometime added to zinc chromate primer to reduce the translucent zinc powder (yellow) to make it cover better. Zinc Chromate was widely used on anything made from aluminum. A lot of time the surfaces unseen were left in just the primer coating but was also used extensively for surfaces top-coated with various paints.
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