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Thread: Powdercoat Removal

  1. #1
    rcbif's Avatar
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    Default Powdercoat Removal

    Well it seems that 2 steps forward, 1 step back is the theme of my 2nd hand model 5 kit build.

    I was doing some powdercoat touchup work on some fuselage tabs and such the other night. Lots of the tabs have sharp edges, and that was where a little line of rust showed thru the powdercoat. (the sharp edge makes the powdercoat in those areas thing to non-existent).

    I removed the powdercoat on a few of these areas till I could no longer see surface rust. Well, a few of these, the surface rust kept going along a tube to the firewall mounts.

    This powdercoat was so adhered from the surface rust, I would peel it off in one long sliver with a knife.

    Not everywhere is like this. I did a sample gouge with my knife elsewhere and the powder-coat is stuck good.

    However, this is enough to ruin my confidence in the powdercoat on my fuselage, and I am going to strip and paint.

    The good news is the rust I have found comes off with some scrubs of a scotchnrite pad. No pitting.

    Can anyone share their experience doing this? Did you use chemicals, or blast it all off? If you blasted, did you blast twice - once for the initial, and a secondary pre-epoxy primer?

    It seems blasting only once is ideal since it is metal removal, but tricky since you want minimal time between blasting and primer, especially to keep everything super clean.

    Any input appreciated.
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    Building a Kitfox V Outback in NE Ohio

  2. #2
    Senior Member
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    Default Re: Powdercoat Removal

    When I purchased my Series 5 in kit form from Skystar in 1999, I found my freshly powdercoated fuselage to have similiar problems to what you are finding on yours. Apparently the vendor they used did not adequately prep all the tubing and I found area like you are finding that had to sanded to bare metal and primed/painted. The old kitfox owners (Skystar) had very poor quality control in my opinion as other issues reared their ugly heads during the build. (gaping holes in new fuel tanks that the factory said were pressure tested, poor quality with the quick build wing etc ) From what i hear from new builders now , this is not a problem under the Mcbeans ownership but older unfinished projects that are floating around should always be thoroughly inspected like you are doing. I think you are doing the right thing in taking it down to bare metal and starting over. I would talk to a local sandblasting shop about the project and go from there. I had a small harbor freight blaster that I used to cleanup the suspect areas and that worked fine, but for a hole fuselage i would take it to a blasting shop. Bruce N199CL

  3. #3

    Join Date
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    Angola In
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    Default Re: Powdercoat Removal

    Been there!
    You need to remove that stuff.
    I used some stuff called DZOLVE 15-33r it works great! I stripped the complete plane and gear
    used about 2 1/2 gallons at the most. I made the mistake of trying to wash it off to soon. Let it
    set. It will work for two or three days. This stuff doesn’t stink and doesn’t burn your skin.
    will probably take two applications to get it all. Very happy with this stuff on powder coat!

  4. #4
    Senior Member Dave S's Avatar
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    Default Re: Powdercoat Removal

    Eric,

    My initial thought is to blast everything to clean metal (admittedly that comes from a person <me> who ordered a bare frame and went with blast-epoxy-aerothane treatmet). Also gives a person a good chance to inspect the welds - I did have to reweld a couple brackets on the skystar vintage airframe where someone got a little overzealous with the TIG welder.

    Getting the paint on fairly soon is important to prevent restart of rust.

    When I did ours - I did the dirty in the driveway method of blasting (cost saving) then got the epoxy on by the next day and the aerothane on 12-14 hours after the epoxy on the advice of my polyfiber rep - the epoxy and aerothane really bond well that way after the epoxy solvents are gone but before it hardens off. Spraying tubing is interesting - a person has to hit each tube from about nine sides to ensure the best coverage.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  5. #5
    Senior Member
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    Default Re: Powdercoat Removal

    I had issues with my 6 when I found it. I had it all blasted clean. Inspected and then re coated. I didn't do it. The guy that did said it took about a pallet of media.

    Sent from my SM-G973W using Tapatalk
    Building Model 6
    912 IS
    Garmin G3X
    http://northernfox.build
    C-FKLO

  6. #6
    rcbif's Avatar
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    Default Re: Powdercoat Removal

    Thanks all for the feedback.

    Encouraging to hear some chemicals will work for removal that sound safe for the average Joe to handle. Will have to run some tests. I wonder if scuffing up the top of the powdercoat (not the the metal) with 80 grit would help accelerate the process?

    It's been like this for 20 years, so hopefully a few more months shouldn't hurt. I have a few items I would like to weld on before re-paint during this time anyways, and I'll primer (or maybe just regular spray paint is fine) any bare spots I exposed in the meantime.


    I'm doing the longer 7 turtledeck (gives the 5 a larger cargo opening), so I need new rear tabs welded on for that.

    I'm also going to add an antenna plate in the area indicated in red to give me ideal spacing between transponder behind the pilot, comm behind the turtledeck, and ADSB a few feet infront of the vertical stab.
    antenna .jpg
    (note the existing plate in this image behind my red plate is the model 6's comm location, which I would do as it is shorter, but does not give very good antenna spacing.)
    Building a Kitfox V Outback in NE Ohio

  7. #7

    Join Date
    Aug 2013
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    Default Re: Powdercoat Removal

    I did a complete superstol frame and gear. Just brush it on and leave it sit for a few days. It will look like
    it stopped working in a day or less. But let it sit longer. It will turn the powder coat to a liquid that looks like
    fresh paint. Hot water pressure washer is the best way to remove the residue. Totally different than any stripper I tried.

  8. #8
    Senior Member PapuaPilot's Avatar
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    Default Re: Powdercoat Removal

    Quote Originally Posted by rcbif View Post
    I wonder if scuffing up the top of the powdercoat (not the the metal) with 80 grit would help accelerate the process?
    Yes, I believe I found that this would help.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  9. #9

    Join Date
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    Default Re: Powdercoat Removal

    If you want to have the entire frame back to bare metal then take the frame to your local powder coater and have them put the frame into their burn off oven.

    They will set it to like 700 degrees for 8 hrs and the paint will literally burn off. They then sand blast it and it's clean.

  10. #10
    Senior Member jiott's Avatar
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    Default Re: Powdercoat Removal

    It probably wouldn't be practical to do a whole airframe with this, but there was some discussion in the forum a year or so ago about removing powdercoat from smaller areas where you wanted to repaint, weld a tab, connect a ground wire etc. I believe it was Scott Noble or maybe someone else who came up with a Permatex or Locktite product (I think it was a gasket remover) that worked real well. A forum search should find it.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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