Talk Composites - The Forum for Advanced Composites

Repairing gel coat damage

http://www.talkcomposites.com/Topic30938.aspx

By quinn - 11/6/2018 5:22:33 PM

So I layed up another helicopter canopy, this time with frekote instead of pva. Came out beautiful, perfect gloss right out of the mold, but it took a little peice of the gel coat with it. It was a piece of the corner where it goes to the flange. About 10mm long, 2mm wide, not very big. Can I repair this? I used polyester tooling gel coat for finished mold surface. Should I just try to fill it in with the same stuff? It's pretty runny but I might be able to use some tape as a dam to hold it in place. Is this likely to work, or will I just lose it again? I suppose another option is to just fill in the corner with wax the next time I use it. Not a heavily used mold. Might do a few more canopies in it. 
By quinn - 11/8/2018 3:29:45 AM

 
oekmont - 11/8/2018 3:04:35 AM
You can use epoxy, too. I did with some of my earlier tools, wich were made quite bad, and got damaged from time to time. The epoxy repairs never got damaged again, while the polyester repairs were just as good as the original gelcoat. But this was more of an demoulding issue. Usually, the original gelcoat should perform just fine.

I'm guessing it stuck right there because I was being very careful to not roll over the flange corner of mold when sanding and polishing it, so I probably had a spot that was hit with heavier grit and then not fully sanded out with finer grit and polish. Next time I'll just use the frekote on plug for making molds so they don't need sanded afterwards. I originally used pva, so the finish on them wasn't perfect without sanding and polishing. Learning as I go. Would have saved a lot of time and money if I bought chemical release in the first place for both mold layup and part layup.