Hi all im looking for a bit of info/help, i have no problem with resin infusion with open face moulds however I’m struggling with flanged/multi piece moulds that are bolted together. i seem to be losing pressure through the two bolted flange faces and bolt holes.
How are you guys solving this issue? any help would be greatly appreciated 
I am sure there is a number of ways. Of course you cant just leave a split flange with no seal at all.
If the moulds are gelcoated then this will seal the job although your bag and gel must meet on the flange somewhere.
We also have moulds with a 2mm deep rebate in one of the flanges where we put a 3mm thick bag tape and then bolt the moulds. We also gel coated the mould too so I am not sure how much reliance there was on the bag tape sealing there.
I think you could also flashtape across the split line?
I envelope bag mine.
I’ve had this same issue trouble me in the past. After a few failed attempts , I ended up making a thin silicone gasket with some silicone 1 caulk in the tube from home depot . I use semi-perm releases on my molds so I applied a thin bead directly to the flange and tightened everything up half way until the silicone cured . After that just be careful separating the two sides so that the silicone doesn’t tear apart .Get it as close to the part edge as possible or inside of the bolt holes and you’ll be set . A very thin bead is all that’s needed and you may even get a couple uses out of each gasket if you work it right . Hope that helps .
HCD - Do you have any photos of this solution?
You may have to be careful if using a silicone based release system as silicone seal in the flange may stick to it very well. I discovered this recently when trying to cast a silicone insert from a mould that had frekote 700NC. It stuck 100%, I had to chisel, scrape, clean and re prep the mould with wax alone to get my insert done. Then re-prep the mould with Frekote to carry on moulding with prepreg.