Chancer wrote:Is it not simply that the reinforcement was foam (hope that right as I cant see the posting from this window) which would compress in the vacuum and that there was initially an air gap between the laid up material and the mould or the process off pulling the vacuum pulled between the material and the mould, thus the reinforcement would be compressed from both sides?
If the hypothesis is correct then using solid reinforcement would prevent it.
good observation, it could just be that the strong foam gradually compressed before full curing, then sprang back and the flex of the fiber gave to a slight bulge as pushing back from the now cured reinforcement...
so if not too tricky to prep an already cured part for adding on top of it (do one just need to scuff it like for regular fiberglass?), maybe an a way would be to add the reinforcement on already cured prepeg, possibly on a styrofoam kind shape (inside a plastic wrap) that could be disolved out with acetone after full curing?