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Thread: Top coat layers

  1. #1
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    Top coat layers

    Hello!

    I'm doing some work on my kit car, it has fibreglass bodywork which is only a couple of years old. Anyhow, I made some modifications and applied my polyester topcoat, which is white gelcoat, with 2% wax added.

    I'd like to add another layer of topcoat (maybe several), can I just go ahead, or must it be sanded back, or will there be any wax on the surface, stopping it bonding?

    Many thanks.

  2. #2
    Super Moderator Alex's Avatar
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    Yes you will have to sand the first layer to provide a heavy key(80-120 grit is best) but do this thoroughly and you shouldn't have any problems.
    Nads likes this.

  3. #3
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    Thanks Alex, I'll try it!

  4. #4
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    Hi again, I have put another layer on. The brush strokes are quite visible, I thought cutting back with 120 grit would sort it out. It didn't I went too deep and removed the topcoat. So I tried 400 grit, still I'm removing too much topcoat when I'm trying to flatten out the brush strokes.

    Once it's flat, can I paint, or does the topcoat need to be 'in-tact'?
    I must be doing something wrong. I'll attach some pics to show what I mean:

    Brush strokes:


    More:


    Too much topcoat removed for painting?:

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    PS. I'm using an electric DA sander, and an electric 'detail/mouse' sander.

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    Okay, I think i figured it out - wet & dry is working well.

    However, a couple of areas have gone through the topcoat, I can't feel it, but I can see it. If I'm painting over the topcoat anyway, is it an issue?

  7. #7
    Super Moderator Alex's Avatar
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    If you are painting over this, some may consider you are going too far!! All you are going to need is a good surface for your paint. I find if there are some tiny dimples that I am not happy with, but are too small to sort with gel or normal filler, get some stopper on it.

    Indasa AutoFill GPS Fine Filler 2kg

  8. #8
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    Nads

    Instead of a paint brush why don't you try a roller? The CFS R4S Roller 100mm x 17mm 4mm Short Pile is excellent and will give you a smoother finish.

    Regards

    Drew

  9. #9
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    Thanks for the advice, yes, I think I was (wrongly) trying to achieve an "out-the-mould" finish, before painting. I didn't realise it isn't necessary, if I'm painting.

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