By Andre Hartmann - 4/2/2019 9:04:47 AM
I started to make carbon fiber sheets with the xc110 prepreg end of last year. I need thin sheets (~ 0.5mm, so 2 layers of the 210g Material) which have a perfect finish on one side, both in glossy and matte/satin.
After much experimentation, two months ago, I finally found a way to achieve a perfect result. Currently I produce two sheets in one work cycle, both in the same vacuum bag.
Now my problem: since the last prepreg delivery, I get pinholes on the whole surface again, it seems to be the material itself, because in the penultimate work cycle I used "old" material for one sheet and new material for the other one. Both sheets were made in the same vacuum bag as mentioned before. The sheet with the old material has become perfect, with no pinholes at all (like all times before), while the second sheet with the new material is littered with pinholes and therefore unusable for me. I did a second run just with the new material for both sheets, now both sheets are full of pinholes.
The vacuum was 100% tight in both passes and the oven worked just fine, otherwise both sheets would have had errors (first cycle), I think.
Any ideas?
I am rather at a loss again as many times befor while I was experimenting with prepreg for the first time. 
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By Warren (Staff) - 4/3/2019 12:40:49 PM
You can try the extended cycle.
We think it may be that the outlife remaining and hence the amount each resin has cured is different - as you would expect the new roll has much more out life and the resin is less cured. A small test that has worked in finding the cause in the past is to take a small offcut/test piece and put it in the oven at 60C for a hour. Then let it cool and laminate it as normal and see what results you get.
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