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  1. #1

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    Painting an already painted cowl..

    Got a question for the pro's..

    It's a long story, but my cowl on my 50cc pitts has a crappy paint job on it, lots of spiderweb cracks on it.. It also has some of the worst filling and sanding of the joints I ever seen, you can see everyone of them.. The ring is all high and the center seams are to low, looks like doggy dodo..

    My question is how much of the paint do I need to sand off, not sure if it even has primer on it, you can see the glass pretty good under the right light? I plan on sanding out all the high spots and filling with bondo, will the bondo stick to theold paint long as It's well sanded? What kind of prep would you do? The paint is new, never seen any fuel what so ever, it's just ugly and needs to go..

    Jimbo
    Ultra Sport Brotherhood #92

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    RE: Painting an already painted cowl..

    If the cowl is thin FG and very flexible that might be why there are cracks. I've had to reinforce cowl joints before painting to insure it doesn't crack again. Prime and try wet sanding and adjust as necessary

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    RE: Painting an already painted cowl..


    ORIGINAL: GarySS

    If the cowl is thin FG and very flexible that might be why there are cracks. I've had to reinforce cowl joints before painting to insure it doesn't crack again. Prime and try wet sanding and adjust as necessary
    Gary the cowl is very rigid and well made in that respect.. I will have to take the cowl outside to take pics, the flaws just don't show up on the picture down in the shop...
    Ultra Sport Brotherhood #92

  4. #4
    AmishWarlord's Avatar
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    RE: Painting an already painted cowl..

    Just wet sand all that old paint off and start over with your preferred paint system.

  5. #5
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    RE: Painting an already painted cowl..

    If you use latex paint which is flexable shouldn't spider web on you at the cost of being more prone to scratches do to being softer.

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    RE: Painting an already painted cowl..


    ORIGINAL: AmishWarlord

    Just wet sand all that old paint off and start over with your preferred paint system.

    That's the problem, it has a air scoop on the bottom and vents on the side, very hard to get in and sand all the paint off, not to mention is big....
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    Ultra Sport Brotherhood #92

  7. #7
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    RE: Painting an already painted cowl..

    If it were me I would take some 80 or 100 grit and sand most if not all the paint off. Is it epoxy resin or polyester resin? When you sand, the polyester will have sort of a "sweet" smell to it. The epoxy is for the most part odorless. If it is polyester and is gel coated, my guess is the gel coat is cracking. The only way to fix, is to sand it off the gel coat and and reapply a new surface coat. I would use epoxy to make all the repairs. It will be a lot of work, but it sounds like you want it "right" in he end. I think a big cowl like that will be easier to work on than a tiny cowl. Good luck in your quest!

    Ken
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  8. #8
    AmishWarlord's Avatar
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    RE: Painting an already painted cowl..

    The home stores sell these little sponge sanders that you can use wet. Get a few in the different grits. The foam will wrap around those small curves.

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    RE: Painting an already painted cowl..

    Thanks guys, will do.. I will post my progress here in this thread.........

    Jimbo
    Ultra Sport Brotherhood #92

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    RE: Painting an already painted cowl..

    Hui!
    Agree with kenh3497.
    And after sanding use automotive 2-part paint (must be sprayed on).
    Jan Karlsson - Supplier MVVS Products

  11. #11
    AmishWarlord's Avatar
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    RE: Painting an already painted cowl..

    Here is a post on painting cars. Yeah 2-part epoxy automotive paint does great! Well unless you put it on thin fiberglass then you get spiderweb cracks when the part flexes.

    http://www.autobody101.com/forums/vi...hp?f=5&t=15406

    Here are the 3M sanding sponges I mentioned earlier. You can buy them singly also.


    http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051

    They worked great for taking off paint from motorcycle fuel tanks. I used them with soapy water. Medium to get the hard paint off to the primer and then fine to get the primer off.

    2 part automotive paint is great but I still recommend that you use Latex paint on this particular part. You can color match easier and it's flexible not to mention gasoline tolerant.




  12. #12

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    RE: Painting an already painted cowl..


    ORIGINAL: AmishWarlord

    Here is a post on painting cars. Yeah 2-part epoxy automotive paint does great! Well unless you put it on thin fiberglass then you get spiderweb cracks when the part flexes.

    http://www.autobody101.com/forums/vi...hp?f=5&t=15406

    Here are the 3M sanding sponges I mentioned earlier. You can buy them singly also.


    http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051

    They worked great for taking off paint from motorcycle fuel tanks. I used them with soapy water. Medium to get the hard paint off to the primer and then fine to get the primer off.

    2 part automotive paint is great but I still recommend that you use Latex paint on this particular part. You can color match easier and it's flexible not to mention gasoline tolerant.




    Thanks for the links and tips, I will be sanding tomorrow eve..
    Ultra Sport Brotherhood #92

  13. #13
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    RE: Painting an already painted cowl..

    In the automotive world there is a flex agent you can add to the paint. It's used for the "rubber" bumpers and flexible plastic to reduce the paint spider webbing. I would think all the automotive paint MFG's will have this product.

    Ken
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    RE: Painting an already painted cowl..

    Well we are into it now, you can see how bad the seams are in the pics. Lots of sanding and filler and blending and sanding and filling and sanding.... lol

    AW,
    those sanding pads are the ticket, tanks again for the tips...

    Kenh,
    thanks for the heads up on the flex additive, if I use automotive paint I will be sure to use that...
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    Ultra Sport Brotherhood #92

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    RE: Painting an already painted cowl..

    I'm pretty sure that on that cowl the glass is polyester with a gel coat. The cracking you mentioned is most likely the gel coat that has become overly brittle. Pinting over this will just show the cracks again. For this not to happen you will need to remove all the gel coat. This is the white under the paint. I have gone to using Pactra R/C car paints and Duplicolor touch up paint and then clear coating with Spray Max clear. This gives all the benifits of automotive base/clear at a fraction of the cost and zero cleanup.
    Of course it's true, I read it on the Internet.

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    RE: Painting an already painted cowl..


    ORIGINAL: speedracerntrixie

    I'm pretty sure that on that cowl the glass is polyester with a gel coat. The cracking you mentioned is most likely the gel coat that has become overly brittle. Pinting over this will just show the cracks again. For this not to happen you will need to remove all the gel coat. This is the white under the paint. I have gone to using Pactra R/C car paints and Duplicolor touch up paint and then clear coating with Spray Max clear. This gives all the benifits of automotive base/clear at a fraction of the cost and zero cleanup.
    Even if I use a good primer over the gel coat? I am not100% on this, but it looks like it'sABS plasticand glassed on the inside.. It's a 3 or 4 piece cowl, maybe more, I'm still sanding.. Once I get all the paint off, i will get some close up pics.. One thing is for sure, who ever made this cowl in Gold Wings plant, needs some more practice....

    Jimbo
    Ultra Sport Brotherhood #92

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    RE: Painting an already painted cowl..

    Speed you are right, it's polyester and it's real weak on the top in between the front and back ring. It pushed in and cracked while I was sanding some more, it's pretty much garbage now.. I think I will just rattle can over it, primer and paint, till I get a new cowl...

    Problem is, GMP owed me a new cowl for it since March, still haven't got one yet from them.. Word on the street is your pretty much screwed if you need a replacement part from GW or any of the distributors...
    Ultra Sport Brotherhood #92

  18. #18
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    RE: Painting an already painted cowl..


    ORIGINAL: Mustangman40



    AW,
    those sanding pads are the ticket, tanks again for the tips...


    Power tools....... Every man needs power tools! A 10,000 RPM grinder with some 24 grit would make quick work of the sanding project [X(][]

    Of coarse you MAY NOT have a cowl when the dust settles!

    Looks good so far

    Ken
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  19. #19
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    RE: Painting an already painted cowl..

    There is one more option. The gel coat that is cracking is polyester based so after removing all the paint you can add another light layer of cloth and resin on top of the gel coat. That would solve the cracking and add some strength. I know its lots of work but I did see your other thread and the rest of the airplane looks great. It would be a shame to stop now. Trust me I know how these projects can turn into more then you bargined for. My latest praject has taken almost two years. Granted I have built 3 pylon racers in the same time frame but standing back and looking at the results I feel it was well worth the effort. She is 100% scratch built. The only items on the airframe that I did not fabricate is the spinner, main gear and wing tube. Good luck with your Pitts.



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    Of course it's true, I read it on the Internet.

  20. #20

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    RE: Painting an already painted cowl..


    ORIGINAL: speedracerntrixie

    There is one more option. The gel coat that is cracking is polyester based so after removing all the paint you can add another light layer of cloth and resin on top of the gel coat. That would solve the cracking and add some strength. I know its lots of work but I did see your other thread and the rest of the airplane looks great. It would be a shame to stop now. Trust me I know how these projects can turn into more then you bargined for. My latest praject has taken almost two years. Granted I have built 3 pylon racers in the same time frame but standing back and looking at the results I feel it was well worth the effort. She is 100% scratch built. The only items on the airframe that I did not fabricate is the spinner, main gear and wing tube. Good luck with your Pitts.
    Speed,
    thank you for the advice and the kind words on my project, it's been a chore to get it to this stage with all the issues I have had.. I slept on it and it's one of them things now, if I paint it now, it won't hold up.. I am going to have a real hard time even trying to get another cowl, if i am able to at all and who's to say that won't be a POS as well... I'm gonna give it some more thought today and figure out what I want to do with it.. I have a P-47 that I am building, it's on a holding pattern right now waiting for Robart to release the Gear I need, I plan on using the Liquid sheeting on it.. I might glass this cowl like you suggested and give the LS a try on it to see how well it works...

    Your scratch built looks absolutely awesome man, a real looker and something to be proud of.. I love the colors and the checkerboard on the bottom, my pitts has ablack bottom on the bottom wing and is ugly. I plan on changing it to somethinglike what you did...

    Jimbo
    Ultra Sport Brotherhood #92

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    RE: Painting an already painted cowl..

    Question:

    Is it a must to get the rest of the paint off before glassing? I am just worried I will crack it even more with more sanding.. I can sand off the clear coatpretty easy and scuff up the paint to give the epoxy something to stick to.
    If it has to come off, I guess I could blow up a balloon inside to give it a little more support for sanding. I am going to get all of my cut outs done for cooling on the bottom, it's nice and rigid on the underside, no sense in sanding something i will be cutting out...

    Jimbo
    Ultra Sport Brotherhood #92

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    RE: Painting an already painted cowl..

    My LHS has this in stock, might be the ticket. I am going to email the company and see what they say about going over Polyester and old paint.. Anyone try this stuff?

    http://www.youtube.com/watch?v=yP05qv3QtUk
    Ultra Sport Brotherhood #92

  23. #23
    scale only 4 me's Avatar
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    RE: Painting an already painted cowl..

    Well, if it were me, at this point I'd just sand it all down to as smooth a finish as you can get with 400 grit, don't worry about taking off all the paint. Wash it real good, Then overlay a layer of 5/8-3/4 oz cloth and resin as if you were glassing wood , sand it smooth, rattle can automotive primer, spot putty, etc. typical prep and paint to your liking. IMHO It's worth a try.


    p.s.
    Not sure how much experience you have with painting, but if you're going to paint Yellow make sure you have a pure white primer finish to start, every blemish will show through otherwise


    good luck
    You're so smart,, you figured out how to read this!! Or maybe ya just got lucky??

  24. #24
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    RE: Painting an already painted cowl..


    ORIGINAL: scale only 4 me

    Well, if it were me, at this point I'd just sand it all down to as smooth a finish as you can get with 400 grit, don't worry about taking off all the paint. Wash it real good, Then overlay a layer of 5/8-3/4 oz cloth and resin as if you were glassing wood , sand it smooth, rattle can automotive primer, spot putty, etc. typical prep and paint to your liking. IMHO It's worth a try.


    p.s.
    Not sure how much experience you have with painting, but if you're going to paint Yellow make sure you have a pure white primer finish to start, every blemish will show through otherwise


    good luck
    The problem with this is that the polyester resin will most likely have a reaction to the paint used. The bondline between the paint and resin will never cure and then he will be worse off. IMO the only way to get a good finish at this point is to get it to the gel coat and then glass over the whole cowl. Spray Max primer to fill the glass weave and then shoot a base of Pactra r/c car sprint white. The black can be Pactra car paint too, the silver stripe can easily be done in Ultra trim. The yellow can be lustercote. Clear with Spray Max clear.

    http://www.66autocolor.com/Spray_Max...pm-3680061.htm

    http://www.66autocolor.com/SPM_36800...pm-3680032.htm

    Of course it's true, I read it on the Internet.

  25. #25
    scale only 4 me's Avatar
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    RE: Painting an already painted cowl..

    So you're saying paint can stick to resin, but resin won't stick to paint?
    You're so smart,, you figured out how to read this!! Or maybe ya just got lucky??


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