Talk Composites - The Forum for Advanced Composites

Pinholes on surface

http://www.talkcomposites.com/Topic20225.aspx

By LeeBrett - 1/13/2016 3:57:16 PM

Hi guys, I am still learning and I have been using a small mould as a test.  I have just pulled my small money tray made of 2x2 twill carbon out of the mould and there are tiny pinholes on one side of the surface, I am sure that the bag kept full vac all the way through the infusion so my question is what are the main reasons for a pinhole finish. 

I have been working in the garage which is cold but have my mould on an electric blanket to keep it warm.  the only thing different with this infusion is that I didn't use any spray tack on the surface. 

I am quite happy to have these little problems as I want to learn as much as I can but I need to have an understanding of why things happen and how to improve.

Thanks in advance
By Hanaldo - 1/15/2016 1:47:32 AM

Yeh I'd say it's a little bit dry for a cosmetic surface. You'll get away with that when everything else is done perfectly, but if you've got some air bubbles in your resin pot from mixing the resin and you infuse a touch too fast then all these little things add up to give you issues like this. 

If you let your resin flow for another 30 seconds after clamping off the vacuum line then it will help eliminate these issues. Realistically, and extra 10 grams of resin isn't going to make any discernible difference to the strength or weight of the part but it can make the world of difference to the cosmetic finish.