Plug paint pickling!!!

Discussion in 'Materials' started by mickbrowne, Jul 7, 2012.

  1. mickbrowne
    Joined: Jul 2012
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    mickbrowne Junior Member

    Help!!
    :confused:I've just spent several months building the plug to take molds off for my latest project. The whole thing was painted in 2-pack automotive paint to give a super glossy finish, but last night I gel-coated for the first section and the paint has "pickled" up!! This paint is now 8 weeks old, and should be fully hardened off, yet the polyester gel coat has stripped it better than any paint stripper I've ever used. BUT, only in 1 inch wide strip along 1 edge.
    Luckily, the damaged part is a small panel, and I can probably save it, but as you can imagine, I'm reluctant to try again on the larger panels.
    Anyone know why this may have happened, or, even more importantly, how do I prevent this happening again????:confused:
     
  2. CDK
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    CDK retired engineer

    Probably the 2-pack paint wasn't completely mixed when you started painting along the edge, so the paint dried there without curing.
     
  3. mickbrowne
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    mickbrowne Junior Member

    Paint pickling

    Thanks for your reply but I'm not sure it helps as the paint was fully mixed before spraying and the same gun full of paint used for this whole panel.
    As I said, there's a lot of time and effort gone into the plug preperation and I REALLY don't want all to have gone to waste. I was led to believe that 2 pack paint would be the best surface preperation, but now I'm wondering if I should re-coat the whole thing in something like a cellulose laquer???
    I'm going to experiment on the panel that's already damaged to see if I can duplicate the problem but I'm not touching the rest of the plug until I have some definative answers.... Anyone???
     
  4. SamSam
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    SamSam Senior Member

    Was it the paint on the plug or the polyester gel coat that "pickled up"? What did you use to prep the plug before gelcoating? How did you apply the gelcoat?
     
  5. mickbrowne
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    mickbrowne Junior Member

    Paint "pickling"

    Hi SamSam
    It would seem that the polyester gel coat, which was a tooling gel, has lifted the top-coat paint off of the primer (also a 2 pack). The primer appears to be un-affected. The paint was well cured (about 8 weeks) and was treated with 10 coats of release wax and 10 (very light) coats of PVA.
    Once I cleaned up the mess where it pickled, the remaining edges of the paint were "soft" to the touch and could be peeled off the primer as a thin sheet.
    I left the remaining gel-coat overnight, and then peeled it off the paint, the wax and PVA alowed it to part off in long strips with a finish that would have made a reasonable finish to the mold surface.
    I've tried to duplicate the problem on the remaining paint on the panel, but try as I might, (I added extra acetone to one test area) I could not get to do the same again. I even made a clay "well" and poured in neat acetone, but to no effect. I'M CONFUSED!
    Oh, by the way, the gelcoat was originaly thinned with 10% acetone and then brushed on.
     
  6. Herman
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    Herman Senior Member

    What kind of 2C paint did you use? There are more types available that do NOT work than types that do work....

    Your paint very probably is an acrylic, which can bubble up, cause your moulds to stick, and other fun things.

    Please use a 2C PU paint, and TEST prior to use in a production environment. I am sorry I cannot be more positive.
     
  7. mickbrowne
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    mickbrowne Junior Member

    Cheers Herman, I think you;ve hit the nail on the head!! It WAS acrylic! Damn! Any ideas what to do from here?
     
  8. tunnels

    tunnels Previous Member

    Use Dura tech !!

    Automotive paints have no place making plugs and moulds ,2 pot or other wise !! marine maybe but have to do a little testing of you own . . styrene and wax and all the other polyester products . No dont pick on epoxy or you will have yet another set of failures .
    Duratech is the safest product t use !! its compatable with everything and i dont know of anything that affects it its the number one chosen product to paint plugs by just about any one in the industry can be shined and polished and then waxed and have release agent applied , gel coated , and a mould made will very little worry !!. . :D:p:p
     
  9. Landlubber
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    Landlubber Senior Member

    Use Dura tech !! .....simple eh.

    The poor man pays twice......
     
  10. mickbrowne
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    mickbrowne Junior Member

    Thanks guys for all your replies. I've done some more research now and it would seem that "Duratec" is the right solution. The only remaining question is, can I spray it over the acrylic laquer that's already on the plug, or am I going to have to strip the whole thing down and start again?
     
  11. Herman
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    Herman Senior Member

    I would suggest doing a test, a do a lot of reading on Duratec. I believe it can be mixed with another product which makes it almost like a paint.

    Please do also test with another 2C paint. (PU based). Here in The Netherlands many plugs are finished in "Double Coat" which is a PU/Polyester modified paint. After 7 days cure it is styrene resistant. Perhaps you can get the stuff over there as well.
    The advantage is that you can spray paint it, leaving an A-Class surface without rework.
    If you can't find it there, let me know. I am a dealer of the stuff in NL, and could send you some.
     
  12. Leon01323
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    Leon01323 Junior Member

    Thats mad that it managed to go through your PVA,, I too have also had this happen to me and it was down to using the wrong type of paint. Whenever ive now mould anything i do many layers of PVA until my piece has turned blue let it dry and then run my first piece, The heat from the making of the piece i find helps cure the mould. I know this is not what normal people do and id probably frowned apon. I have, when ive been up against it made the mould and the first piece in same day. Once ive had the first piece come out of the mould i find after waxing nothing then sticks to it, even the next day.

    It will more than likely bite me in the *** soon, Not yet though.

    Know your frustration, you could if you wanted do a heavy coat of pva on your piece your not sure about as this will give a physical barrier but you wont get the smoothness you worked so hard for
     
  13. tunnels

    tunnels Previous Member

    Points to always remember

    When you making plugs and mould always do research and use the materials that are compatable . Acrylics and automotuce paints are not suitable even 2 pots are not all the same . Use recognised and tried and tested and proven by many others every where . the only automotive product that reasonable is fillers like bondo of others lke it . Its polyester based any ways so your part way there .
    Sad but yest start again and dont forget !!

    The poor man pays twice......That is so true!! trying to cut corners and save a few pence you end up paying double of lossing entirely !:D:):p
     
  14. the1much
    Joined: Jul 2007
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    the1much hippie dreams

    the mekp in your poly ate through in a spot (along the dges) where most without knowing puts it on thicker,,and the thicker paint hadnt fully cured yet....but thats jus off top of head lol,,maybe my 2 cents worth ;)
     

  15. tunnels

    tunnels Previous Member

    What ????????????????????????????????????

    How would just the mekp eat through ?? mekp is catalyst and its mixed with resin so why should it eat anything ?? by its self it should not be any where near any part of the job !!!!!:confused::eek:

    but thats jus off top of head = better put the top of your head back on and keep the inside warm!!
     
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