Inorganic Zinc coating

[sailamaryllis]

I have a galvanized mild steel engine bed grid system on a 44 ft. monohull. The galvanizing has spot deterioration in some areas. I'm wondering if anyone has experience using inorganic zinc coatings. If so, can you recommend a product/manufaturer?
Bruce

[Travis McGee]

Hi Bruce,
This is right up my alley. I have a 20-year-old 48' steel cutter that is coated outside with Devoe inorganic zinc. It works fantastically well on the outside of a hull, where it can be sprayed evenly over the freshly blasted steel. This thin coat of zinc is truly like "cold galvanizing," and when I chip the top coats of urethane and epoxy paint, say, by dropping a heavy winch handle on the deck, the zinc looks like it was sprayed on last week, And, there is no hurry to paint the ding. With the zinc protection alone, the steel will not rust.

BUT, you want to apply zinc to the interior. Here, inorganic zinc will not work, because it must be applied in a very uniform thin film, drying to leave only a uniform coat of zinc particles. Inside of my boat, I used organic zinc-rich epoxy, another Devoe product. This is because inside, it is inevitable that some puddling and pooling will occur around frames and in corners etc. The organic zinc-rich epoxy at least ensures that the carrier of epoxy will kick off and harden. So you might want to consder this option.

Or, you could go right to Devoe Bar-Rust 235, over your steel. Prep it as well as you can with what you can use: sandblasting best, needle gun 2nd best, wire wheels in an assortment of tools next best. Get it as close to bare metal as possible, paint on a few coats of Bar-Rust 235, and you should be good to go. Bar Rust 235 is fantastic stuff, it's not even expensive, and it's easy to apply. As always, the best possible steel prep is key.

[sailamaryllis]

thanks! We really appreciate your response. I'm familiar with Devoe products as being something that is commercially effective. What we're working with is galvanized steel that has some spotty surface rust. It's a grid support system inside a fiberglass boat. So we're just looking to do isolated areas to stop the spotty rust areas from getting worse. To prep the rusty spots, I'm currently using Ospho and a wire brush. I'll check out the organic zinc-epoxy and the Bar-Rust 235. Thank you again.