Zenith Aircraft Builders and Flyers
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"prime and paint because it's steel"
Watching the fuselage DVDs last night, Jon makes the off-hand remark that before installing the control rod they've been primed and painted because they are steel. I get to exercise my virgin knowledge again and ask if someone can explain ?
Is there some special technique or paint that needs to be used on the steel parts ? Could I leave them in black if I wanted (I probably don't) ?
I suppose as my fuse is coming together I better start thinking about the interior.... I presume most people paint, rather than leave it bare (much harder to polish inside than the outside) ?
Thanks
Paul
Replies to This Discussion
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Permalink Reply by Jim B Belcher on
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Steel needs a protective coating because it will rust. The classic answer was zinc chromate primer, plus a coat of something like aircraft enamel. I don't know what your black coating is, but there's a fair chance that it may be the protective coating you need. If so, adding a color coat over it might be optional. I don't like more coats of paint (or primer) than is really necessary because of weight impact.
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Permalink Reply by Mark Maltais on
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A nice coat of self-etching primer (about 10$) a can works great, it won't scratch off easily then a light coat of enamel and it's good to go. Don't go to thick, it causes issues with some parts that have to be put into bearings and such. You have to do paint the part or it will rust quickly. They are a pain to paint. If I were to do it again I'd have ordered them powder coated. I was somewhat lucky...a few of my parts came powder coated without me asking! :)
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Permalink Reply by Paul Sanders on
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Interesting.... I don't see powder coating as an option on the kit order page any more.
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Permalink Reply by Phil Smith on
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Paul,
Bite the bullet and have them powder coated (light grey for me) including the engine mount and throttle bar (white). The only trouble you'll have is to decide where to mask off for future mounting areas. If you go through and think it out you will be able to determine these places. More is better so all is covered. A trick I saw and used to remove the coating - very tough stuff - is to heat the area and then lightly scrape it off. One I missed is the mounting areas of the two rudder bars at the middle mount area and it was a bitch to get clean. Talk with your Powder Coater and determine what to use for masking. What I did was to mask the areas I wanted free of coating then let him clean and re-mask with the proper material - it has to withstand a heat soak. Also if you add up all the trouble of preparation - bead blasting - primer and finish coat it will probably come out about the same in cost with a lot less trouble and a much more durable finish. BTW I also cleaned all the insides of the tubes that I could get to with solvent and brushes for shotgun cleaning and then treated them with ACF 50 corrosion inhibitor. It weeps out a little but much better that rust.
You can see a lot of the parts in pictures I published on this site. I did all the steel parts including the lift struts etc and have been very satisfied..
Still Grinnin!!!
Phil
Ch-701
Buhl ID
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Permalink Reply by John Austin on
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Just a FWIW - some advise not to powdercoat engine mounts. Powdercoat forms a plastic film, and potentially a weld could crack but the powdercoat doesn't, so the crack is hidden. Apparently, if a mount is painted, it's more likely to crack the paint, too, and be visible to inspection. That's also why it is a good idea to paint engine mounts a light color so as to aid the visibility of cracked welds. I painted my mount but powdercoated a lot of the other steel parts.
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When I ordered my motor mount from Zen I was told they don't powder coat them. Not sure if that means they don't do single parts or just don't do motor mounts.
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Thanks all for the replies, the more I read the more foolish I feel - of course I need to rust proof the steel parts! :) Though out here in the desert I can probably get away with quite a bit.
I like the powder coating idea, and it looks like there is at least one place near me that can do it. Maybe I will go talk to them.
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Permalink Reply by Chris Aysen on
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Paul - I can't say for sure because obviously I can't see your parts; but most of the time steel mills will coat their product with a rust preventive before shipping. That may be the black stuff you have on the steel. If your not set up for powder coating then you have to have someoneelse do it for you. I purchased the equipment necessary to do it but the process requires heating components and really a pain in the butt for just a few parts. It is a tough and long lasting coating that probably should be considered on some of the parts. However, don't be afraid of using the normal process of primer and paint. When done properly it to is also a tough coating.
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Looking more like I'm going the primer and paint route, the nearest powder coating place is 100 miles away or in Mexico (I suppose I could have an interesting day time while I wait!).
What is a reasonable way of getting the steel ready for priming? I've read accounts that sound more like a chemical lab, I'm just a guy in a hangar with a table and a pair of gloves......
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I used acetone to clean the parts as they usually have a film on them from the factory. It's more than good enough, just use a clean rag and make sure you get in all the cracks and other edges that are hard to get too.
You can lightly sand them to help primer adhesion, but not necessary if you use self etching primer...about twice as much as regular primer. Don't go to thick on each coat. I did all my parts with about two cans of primer, including a second coat. Then just paint them with a good quality paint. I used a regular spray can of high end paint and it worked fine, especially since most of these parts aren't seen after you close everything up anyways.
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Permalink Reply by Jimmy Young on
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Paul,
My experience with rattle can primer and rattle can paint on steel parts has been unsatisfactory. I did that on my old Kolb before I new any better and found I had rust developing rather quickly. I live in a much more humid area than you, but anything short of good surface prep, two part epoxy primer and two part urethane paint on steel will result in rust showing up within a year. It usually shows up first on the parts facing the slip stream. Without mentioning any names,I've seen more than one 750 that used rattle can paint on the steel showing the same signs of corrosion I am describing. You only get to do this once the easy way, so I would suggest you either use the 2 part epoxy primer and 2 part epoxy finish paints on all your steel parts or have it powder coated. Nothing worse than finding out 9 months later all of your steel parts showing signs of corrosion. I'd hate to see anyone build a plane without at least considering this because it's a major pain in the rear to fix it after the fact.Good luck with it -
Jim
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By the way, Rustoleum makes a true, two-part epoxy primer in a rattle can! It has a button in the bottom of the can that releases the activator and then you've' got a day or two of pot life to use the spray can. It's pricey, about $30/can as I recall, but it's great for one-off uses such as priming steel parts and not having to clean up a gun is worth the price alone!
You'll only find it at industrial supply stores like Grainger, etc.
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