So my fuselage is done and I’m getting ready to epoxy prime it.
1. What quantity of primer should I expect to use? I know that a tube structure uses lots of product and that most of it is overspray.
2. Topcoat? Is it needed anywhere besides the cabin? Thanks
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If using Poly Fiber EP420 for example, a qt. when catalyzed and thinned will do a fuselage if you don't go crazy and you use an HVLP system, which saves some material. I usually buy 2 Qts. just to be sure, and get into the second qt for tail feathers etc.. 2 is certainly enough even if this is a first effort. I only topcoat the cabin area with Aerothane or the like. If the fuselage were to be white for instance I would use white epoxy on the tubing, then when I finish paint a white fuselage, the cabin area can be done at the same time. Different colors for cabin area and fabric require careful taping. When painting the tubing I turn the gun down to spray an area about the size of a fifty cent piece and use a low volume setting and might end up doing at least 2 coats; then go around and touch up any light areas. Hope this helps, regards.
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As Crow mentioned, 2 qts of catalized material should be enough and account for loss due to overspray.Helps to do the first coat (quart) in a different tint than final coat to insure full coverage and proper mil thickness
I SOOOOOO do not miss priming fuselages!!! powder coating is so nice!! last on I primed was probably 1994?
2qts is enough to get the job done. If you have a PPG dealer near that’s what I would use, Omni MP171 or DPLV48 are the two that I like. I would top coat the fuselage, primer is made to be the base and not exposed to the elements, I use PPG AUE-100 for my top coat it’s stronger than a woodpeckers beak and sprays great.
Last edited by PA-22/20-160; 02-13-2019 at 09:10 AM.
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Thanks. I have plenty of DPLV. I was unsure if I should topcoat where the fabric would effectively cover the primed tubes.
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Don’t know how the glue would react to the primer but I would never leave primer uncovered, might as well do it right and topcoat the whole thing and not have to worry about it.
Poly Fibr EP420 is a two part epoxy and not bothered by glue or anything else and saves weight compared to top coating. I use etch primer and then this epoxy and have some out there decades old without any problems. Is available in green or white for sure and maybe one other color, can't remember what.
FWIW I had to replace a broken engine mount on my C180 a couple years ago,
and my buddy suggested I paint it white.
I didn't like the idea at first, but after doing it I think it looks pretty cool.
The whole idea of white is to make it easier to detect cracks--
not always so easy on black tubing.
Also FWIW, no first hand experience but I've heard that cracks can be difficult to detect underneath powder-coating.
Cessna Skywagon-- accept no substitute!
What did you use for the self etching primer? I was under the impression that you should not use it under a epoxy primer. I have been wrong before, so my wife tells me.Originally Posted by supercrow
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I have used good quality etch primer ( not rattle can) for many yrs with excellent results. I have used several different brands and lately have been using Nason 491-17 etch prime 2K and 441-43 acitivator/reducer ( because I can buy it in gallons locally) mixed 1 to 1. A qt of primer and a qt of activator will do a fuselage. IMHO a common error with these types of materials is to try to "paint" the steel as you would with the finish coats. A light coating gives the best adhesion and longevity and I have seen no adverse effects of top coating with a good quality epoxy or polyurethane finish, and have pulled fabric off some 30 yrs later and they look just like they did when first coated except where the glue was applied, and often the glue stays on the epoxy and doesn't peel the coatings. I do try not to leave a fuselage too long with just the primer on it before topping it with something else, which means you should be really ready to go after it before you start priming (hopefully don't have to back up for welding etc.) I have had no issues with 2 part finishes over etch primer, but that is just my observations on the work I have accomplished. Hope I haven't muddied the waters for you.
That is some great information,
Thanks. Hopefully all the welding is done at this point. I have 3x checked over the plans and had two sets of eyes on it.
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Sounds like you're good to go. Best of luck with whatever plan you decide on. Reid
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