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Gelcoat pinholes problem.

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Mac790

Well-Known Member
Joined
Jun 22, 2008
Messages
1,525
Location
Poznan, Poland
This thread isn't aviation related but it's composites related, I don't know other guys with so much experience, so I decided to ask here I'm hoping you don't mind. Sorry for so many pictures, but it's easier for me to show something rather than try to explain.

Here is a story.
I'm prepering my car for sale (pic1) (need some money for a new one:) and I'm thinking also about home-made CNC router, I'm not going to make all these plugs by hand again, etc). At the moment it's a little bit disassembled pic2, I have to make a new scuttle, because I had some issues with my windscreen and vipers.
When I was doing my composite parts last time (about 3-4 years ago), sometimes I had problems with a pinholes in the gel coat. I'm not exactly sure what was a cause of these pinholes, I was trying different speed of mixing gel coat with a hardener (slower, faster), different tools (sometimes I was mixing a with rod, sometimes with a wooden strip), and beacause I was applying the gel coat with a brush, I was trying to apply sometimes thinner sometimes a little bit thicker layer.
In most cases were fine, but a few times I had those ugly pinholes. Believe me you can be really p...o.. when you find it in the mirror finish (pic3,4) part, here is the worst and the only part with pinholes after air bubbles, those white spots (pic5). I was trying also mix gel coat with an electric drill at very slow rpm, and I think it was the best solution to this problem.

So my question is, does anyone have similar problems, how to deal with it, how do you mix your gel coat, etc.
I know that we have guys with not only theoretical knowledge but also with a lot of experience, so I'm hoping that someone give me a few directions.

Thanks
Seb
 

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