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.

Hi Andre,

What we have found is that very occasionally, and usually only on very thin lay ups, new material can  trap air a little more than older material.  What seems to happen is the resins are staged at room temperature after manufacture to settle and even out before  being frozen.  The older the  material is and/or the longer  it is spent out of the freezer, the further this improves on really fresh batches.  What we have found is that after a few days out of the freezer, the resin fractionally looses  a bit of tack which helps with expelling any trapped air underneath..    Another technique that works in these cases  is to allow the vacuum bag to debulk for an hour or so before you put it into the oven to cure as the extra time helps remove all the rest of the air.  Hope that helps.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Hi Warren,
yesterday I did a third run, allowing the vacuum bag to debulk for a hour before puting it into the oven. Unfortunately this didn't help at all. This time I also did just one sheet, it got as many pinholes as the run before.

Do you got any further idea? Maybe another cure cycle than the standart one? 

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.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant