Talk Composites - The Forum for Advanced Composites

Surface finish on complicated part

http://www.talkcomposites.com/Topic40268.aspx

By Daniel Kovalik - 8/14/2021 8:16:11 AM

Hello,
I have a question about a problem I am having. I know that it is not advised to use spray adhesive when you want to create visible carbon parts with infusion BUT, I am in the process of creating quite intricate airbox design which consists of 3 main parts one some small bits and pieces, but the main shape is the most complicated one, it is 2times split mould, one I manage to infuse in one go, the second shape needed to be infused separately and then joined together in mould.

My question is, i have quite a bad surface finish and I would say it is most likely due to using spray adhesive, but in my opinion it is not possible not to use one becuase of the compliacated shape the mould/part has. It also leaves residue in the mould after releasing and it can be cleaned off with acetone, but then i am worried that it will also wipe away separator (i am using Semiperm™ Monofilm)

For spray adhesion I use INFUTAC clear - which states it is suitable for visible carbon parts...

The proces of what I had to do now was to clear it with layers of resin and sand it down and after that apply final matte clear.

Below are pictures of parts out of mould.
What would be your advice? I want to try spraying the adhesive on the fabric instead of mould, but i dont know if that will help something.
By TogaMan - 12/1/2021 11:03:20 PM

Thank you for posting this! I had the same question! (Spray glue to hold cloth down/PVA) Fortunately, this part I am working on is a below the hood part nobody will see.

I have had a tricky time settling on finish/gel coat on my main hull The body/neck of a small viola/cello/guitar size instrument I make. I was intending on going to an in mold gel coat but want to avoid polystyrene types and the thixotropic epoxies were hard to apply in terms of uniform thickness. (Plus, they were a bit too tenacious sticking to the mold (even with ample PVA etc.). I have been experimenting with food grade epoxy finishes but do find them tricky with contaminants/fish eyes etc. Besides Acetone, any good pointers on surface prep?