Powder coating

[Flybyjim]

Just wondering about the powder coating of the air frame and how well does it work with the poly fiber chems. I have covered a few planes in the past and have always used an epoxy finish that the MEK will not attack. With a polyurethane finish if this is what the powder coating is, I am concerned with the adhesion properties with a MEK based glue when gluing to the tubes of the airframe.
Thoughts?
Jim

[Dave S]

Jim,

When I covered my aircraft I was fortunate enough to have a poly fiber dealer with lots of experience very near by. He was in the aircraft restoration business many years and often took and an old airframe and had it blasted/powdercoated. I also have other friends who got the powdercoating on their Kitfox who did polyfiber...MEK does not bother it. These experiences plus the fact that the powdercoating is the material of choice by the Kitfox factory tells me that powdercoating and polyfiber work just fine together.

FWIW - when I purchased my kit I ordered a bare frame as I had previous experience with epoxy primer and used this as a way to save a few bucks as I did not have any surplus money in the first place and was totally accustomed to sand blasting and epoxy work......admittedly a dirty job, but I am fine with that. Also wanted to use the sandblasting step as an opportunity to carefully examine the welds and joints - I did a coat of aerothane on top of the primer.......found out from the Poly Fiber dealer, if you time it right (about 14-18 hours between) the epoxy and aerothane are as good as one. MEK does not attack aerothane either.

Sincerely,

Dave Syverson
KF7 Trigear
912ULS Warp Drive

[Flybyjim]

Thank you for the reply. Always looking for advise from people who have been there, no use to reinvent to wheel

[jullian]

Powder coating especially on fuselage frame, engine mounts etc is not to be done!! Yes, it gives a nice finish, especially to kitchen appliances, but has no place on your aeroplane. Part of the problem is that unlike paint or other protective coatings, there is no active corrosion suppressing ingredient such as zinc chromate, and it is insidious as it will not 'bubble' like paint will when there is corrosion under the surface. check more on http://www.automaticcoating.com/serv...owder-coating/

[Peteohms]

I had the jury struts on my plane powder coated and that lasted a year before you could see the rust underneath. Had my brake pedals done at the same time and no rust after 3 years.

[snowpaw]

This was interesting. I'm about to remove the powder coating from the KF IV 1050 I'm restoring, in order to inspect all metal Surfaces and to repair some wrecked tubes in the fuselage. I also would like to have another color on the fuselage. Does anyone of you have recommendations regarding the below ideas:

Alternative A (Which is the one I've been considering)
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- Remove powder coating with paint removal
- Sand surfaces without rust
- Sand/soda blast surfaces with rust
- Clean with thinner
- Prime a.s.a.p. Will any epoxy primer work or shall I use Polyfiber?
- Paint

Alternative B (primary reason would be to save time)
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Only remove powder coating in areas where rust today is visible or can be suspected from e.g. bumps in powder coating. The rest as above.

I don't mind the work in alternative A as it would make me feel safe that Everything is checked, but would appreciate any good thoughts.

[alanr]

As I see it, it depends on the condition state of the steel at the time of powdercoating.
If the steel is clean, i.e no external rust, with no surface corrosion at all in evidence applying a powdercoat finish will provide an excellent protection from future external rusting. However if the steel is in less than a perfect condition at the time of application of powdercoating this will seal in the rust and create the perfect condtions for the growth and proliferation of the rust.
So to apply this logic to airframes we do trust that when we buy a powdercoated airframe the steel is in perfect condition when the coating is applied. Does anyone have any doubts on this being so on a Kitfox?
I also understand that the airframe tubes are internally oil protected so inside-out rusting should not occur either.

[Paul Z]

I know I used it a lot in Systems we design for Defense Industry. We actually would powder coat raw cast housing, then send them to the machine shop for machining, and then touch up chemical finish, and a little touch up paint, and they were ready for assembly. The finish was better than the paint processes, and held up better in the field. I constantly was seeing design changes come through to change to Powder Coat Finish because it was holding up so well in the field. We had one program that every part that was exposed to the environment, was changed from a paint finish to a Powder Coat finish because of the cost savings, and because of the reduced amount of paint touch up required.