Hi everyone, I was wondering if you guys could help me troubleshoot. I had some issues vacuum-bagging a 4' x 2' sandwich core panel. We used 18 oz. of epoxy resin/hardener for 27 oz of plain weave carbon fiber to follow a 40/60 ratio of resin to carbon fiber. We had a laminate sequence of 0/180/core/180/0. We had issues pulling a vacuum but we managed to achieve a vacuum level of 23 in Hg. During the layup, the carbon fiber seemed saturated with resin but I found today that the resin did not fully wet out the carbon fiber. We also had issues with striations on the surface and strands of breather sticking to the top of the layup. I believe our issues are a combination of not using enough resin (by not accounting for the resin uptake of the Nidacore) and not pulling a high enough vacuum. However, I would really appreciate any insight into this. I have attached some pictures of the panel for reference. Thanks!

Compressing and consolidating the fibres are different but linked.  In some cases a bit of compression is useful to avoid voids and excessive resin content.  Also in some woven cloths it can be advantagous slightly as the straighter fibres after slight compression will perform mechanically better.

However with thick laminates, if compression has a significant difference on thickness then stiffness may suffer slightly in a similar principle to using a thinner core on a cored panel.   I guess its a fine balance.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant