Hi folks,

I'm trying to do my first infusion at the moment, and I'm being driven crazy by the vacuum leaking.

The mould I made myself, it's been painted with 2k automotive paint & clearcoat, the surface finish is good but not perfect (a few minor bits of 'orange peel' texture).

I've tried bagging it three times now, the last time I tried applying the tacky tape to the bag first (which I found a lot easier actually), each time it will leak though.

I have spent ages working the tacky tape in to make sure it's firmly pressed down, no creases etc. Where the vac line enters I made sure the connector was clean and no creases etc.

Initially I had applied release agent to the whole mould, including where the tacky tape goes, after the 2nd attempt I tried to clean this off using brake cleaner in case it was causing an issue, but still no vacuum. I don't know if that could be the issue, but I presume the brake cleaner would remove the easy-lease...

I can hear the bag moving slightly as the vacuum fades and it seems to come evenly from various places, so I can't pinpoint one place where the leak is occuring.

Would appreciate any tips on this as I'm going mad!

Thanks,
Rich

Here's a bigger photo

I read somewhere about the cut edges of the infusion mesh possibly puncturing the bag, and that you should lay something over the tops of these to prevent (ie peel ply)... does this sound likely? I can understand why it could happen but would it happen 3 times out of 3?

is your mould completely vac tight? no porosity in it? what is the mould made from?

I would assume the mould is vacuum tight, it's MDF wood, then sprayed all over with epoxy primer, then polyurethane primer, then 2k paint/clearcoat... I can't imagine the paint/primer combination is porous?

Spent ages on the tacky tape, got it 100% perfect with no creases etc, I'm sure that's no the issue.

In my experience, 99.9% of leaks come from the bagging tape. It can look absolutely perfect and sealed, but that doesn't mean it is. I often have to heat up my bagging tape to 40 or 50 degrees, then go around it thumb by thumb pressing it down and sliding it around to really make sure it's down, making doubly sure to press down the pleats and hose connections. Your thumbs will be very sore by the end of it. 

If you are concerned about the mesh puncturing the bag, just run some flash breaker tape or masking tape over the edges.

Bagging is a fine art.  Once you have the experience it will become relatively easy but until then it can be the most frustrating thing trying to find that tiny leak when you've looked everywhere for it.  It can be something as small as a single fibre of fabric breaching the tape which causes a small leak.

If you try all that and still struggle, try envelope bagging to rule out porosity in the mould.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Looking at your set-up, I'd look to reduce the number of pleats and, if necessary, make each one a touch bigger as generally speaking most leaks occur around the pleats. Less pleats will, hopefully, mean less potential leak sources. I've also found thar doubling the tape over also helps keep the pleats tidier and a bit less prone to wrinkling under vacuum. 

Hi guys,

Thanks for all your advice so far.

Interesting points about the temperature, it certainly has been cold in there when I've been working, so I'll try warming the tacky tape up next time. That said, it did seem extremely sticky and well stuck to the mould when I removed it. Perhaps next time I'll bring it in the house for the bagging, rather than doing it in the garage...

I'm going to bear in mind some of these comments and have another crack at it in the next few days.