Hi, I've been trying to vacuum infuse basalt fibre using the EC infusion kit with an existing vacuum pump. The mould is made from aluminium, and the A side seems to be coming out really well, but the B side (peel ply side) looks to be aerated between the top few layers every time. I recently changed the direction of flow to run along the part rather than across it, which was an improvement but its still not coming out right. I've tried this 4 times now with various directions and layups but I can't seem to get it to work properly.

I wasn't able to order an EC epoxy as I'm in Australia so have used a local resin supplier. The vac pump pulls a strong vacuum, well under the -30inhg gauge minimum. I haven't degassed the resin.
Is there anything specifically that causes this type of failure?







The left one was resin flow across the part from left to right, and the right piece was flow from top to bottom, having to travel over the bends.

Thanks

Leaving the pump running and the outlet open is probably only going to draw resin away from the part and potentially leave the 'A' side looking starved of resin

To ensure that the whole part is sufficiently wetted-out, you need to ensure that things have infused fully so a resin break can be very useful, especially on small-ish parts and leaving the inlet side open for 30 secs to a minute after closing-off the vacuum side should help

Were ambient temperatures at or around 20 degrees during the cure, as the residue left by the stack removal on the 'B' side can be brittle and white-looking where things have cured in colder conditions? I'm also guessing that your slow hardener might require around 48 hours, at least, to fully cure at a reasonable temperature, so you'd need to be wary of de-moulding too early also

From what you've mentioned regarding air bubbles visible and looseness in the bag, it sounds more like evidence of a leak more than any issue with trapped air and I'm not certain if boiling gas is an issue with epoxies? If not doing so already, it's always worth going around all of the perimeter just before allowing in the resin to flow and pressing the bagging tape down firmly once again to ensure that nothing's slightly loosened when pulling the bag down initially

Sometimes a slight leak might occur after closing things off and this can just affect the 'B' side without affecting the surface quality, if you're lucky. Again, might be worth pressing everything down again just in case the introduction of the resin has served to make anything loosen slightly

Even when infusing fairly small parts, I have not seen any benefit in using a de-gassing chamber, as applying a little control to the speed of infusion and ensuring proper wet-out should allow for sufficient de-gassing during the infusion process itself but it might allow you to rule out this area of concern. I know that some people swear by using them, but mine's gathering dust as it really didn't make any noticeably difference and just slowed the process down. Even with quite lengthy degassing, you're still likely to see some air in the infusing resin.