Thanks Chris, I did actually stumble across your post late last night. 

I'm using an epoxy with a super slow hardener from a local supplier. Last time I finished the infusion I kept the pump on for a few min, then turned it off after clamping off the resin and then at the catch-pot. The resin flow seemed to be solid and free of bubbles on the way in, but a lot of bubbles were forming through the stack even from what seemed to be solid resin. A lot of bubbles formed through the infusion mesh over the curing period once the pump was switched off, and the bag seemed to loosen up a bit in those spots. I had about 10-20mm in the catch pot.

Based on the info I've come across over the last few days, I suspect my issue is going to be moisture in the resin and boiling under vacuum. I'm building a degassing chamber today and will also try the resin break on the next stack. Interesting that the EC videos seem to suggest clamping off the stack and turning off the pump after the process is finished - nothing is said about keeping a vac on through to cure (unless I've missed something).

What type of resin did you use?  I am not familiar with basalt fiber but what you describe sounds like air/vapor/gas problems.  There are lots of potential reasons this can happen so it's hard to know exactly whats up.  I would recommend leaving a resin break between the end of the flow mesh and the vacuum port - just to slow things down and force the resin to displace all the air.  Shooting it side to side (up and over) seems like the best so that you don't get a quick run from the inlet to the vacuum without fulling the edges.  Did you get a lot/any of resin in the catch pot?

I did a post on vacuum infusion problems - may be helpful:

https://explorecomposites.com/2019/11/19/troubleshootin-vacuum-infusion/

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