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Permalink Reply by david shrader on March 21, 2016 at 1:48am

Zinc chromate is a great primer for aluminum due to its corrosion properties in relation to aluminum. For steel a epoxie primer is a much better choice. Rustoleum in the spray can simply isn't enough for a long term solution. There are lots of options, water based products, powder coating, an there's always droping your steel parts off at the paint shop.

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Permalink Reply by Ken and Joel Norton on March 21, 2016 at 7:01am

Thanks David for the reply. I didn't want to powder coat because I read that corrosion can stay hidden underneath the powder coating creating a non visible weak point. I was reading up on stewart's Ekoprime waterbased single component product. It has two good reviews on aircraft spruce, easy to apply. Price wise it's less costly than the ekopoxy primer but more importantly it's ease of application and you can re-use what ever you don't use. I'm leaning towards that right now. Any thoughts? Thanks for your help!

Joel 

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Permalink Reply by John Austin on March 21, 2016 at 7:30am

Another alternative is Rustoleum 2K Epoxy Primer in a spray can/rattle can.  Even though it is in a spray can, it is a true 2-part epoxy primer - there is a button you push in the bottom of the can to allow the two components to mix in the can before spraying.  It definitely is not cheap ($43/can at Grainger), but other industrial suppliers may have it for a few bucks less. On the other hand, the price is not bad for small jobs so you can do it at home and there's no messy clean up of spray equipment.  I used it on my cabin frame and top coated with Rustoleum enamel and so far it's holding-up well after 4 years.

I think I used about 3 cans on the cabin frame, engine mount, and numerous other steel control parts, etc. One tip, prep more parts than you think the can will cover. That way, you can keep spraying and use up the entire can and not waste any. Like all epoxies, once it is mixed there's a definite pot life and you can't use it later.

John

N750A

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Permalink Reply by Lawrence Bird on March 22, 2016 at 2:12pm

Hmmm... prices look all over the place, I see one very popular supplier lists a 6-pack of Rust-Oleum 247598 High Performance VK9300 System 2K Epoxy Primer Spray Paint, 14.1-Ounce, Beige (which I assume to be the stuff) for their "prime" members at $135.  

I may get some and give it a whirl...

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Permalink Reply by david shrader on March 21, 2016 at 10:45pm

Paint is such a contentious subject I don't like posting on it. My personal preference is a PPG Epoxy primer, followed by Imron. These paints are not the kind of thing you can shoot in your garage, paint booth an proper respirator are required. I don't like to mess around with paint, I want to do it only once an never again. I've have seen so many aircraft with corrosion problems it's no joke.

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Permalink Reply by Lawrence Bird on March 21, 2016 at 10:49am

Don’t know the answer to the Rustoleum portion of the question, although I’m curious because I’m thinking of doing just that, but properly done I think that zinc-chromate remains one of the best…   I’ve been opening up an amateur-built tube and fabric bird that was built in the 1970s, flown for twenty something years and then stored off and on, until about ten years ago when it went “to the barn…” The fabric is shot in most areas, but the underlying steel is astonishing pristine – don’t know what application process the original builder did, but the ZC did its job and so far the only areas that are even marginally compromised are areas of later-year mods where the integrity of the original was broken… in 95% the original tubing looks it like it was just closed up just six months ago, even in areas of little or no circulation… 

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