Michael Horowitz wrote:
Duralac Zinc Chromate Paste doesn't appear in the Spruce or Wick
catalog, apparently for health reasons.

I do see it mentioned for sale by marine stores.

Has anyone using an acceptable substitute, easier to locate? - MIke

You can buy aerosol spray cans of zinc chromate paint from ACS. It is
cheap and effective. Don't breathe it. I think the chromium is
hexavalent, i. e., toxic. A light film on aluminum surfaces you wish
to protect is sufficient.

I doubt zinc chromate is effective with steel as it is with aluminum.
Tony Bingelis says that it is not, iirc. I bead-blast the corrosion
from steel, then coat it with an epoxy etch primer, followed with a few
coats of a durable paint like PPG durathane or a Sherwin Williams
polyurethane.

If you're covering the aluminum with polyester fabric, don't forget to
over-coat the zinc chromate with a primer like epoxy to prevent
bleeding when you use polyester covering chemicals like polytak,
polybrush, and polyspray. They contain methyl ethyl ketone which will
dissolve the zinc chromate paint, and it will bleed into your fabric.