as suspected,im struggling to seal my vac fim onto the mold.i know its leaking from somewhere and i suspect its the pleats in the film,ive tried to seal it down with a roller and small bits of tape on th eobvious points but it looses all vacuum within 5 minutes.im using the 1mm thick vac bag tape from airtech and my film isnt ‘proper’ bagging film,its a clear film used for shrinkwrapping,we used to cook it for 5 seconds at 190degc to shrink it over a tray of canned food,it may just be that this film is totally unsuitable and i need to get some proper stuff but the film in itself doesnt seem to ne leaking/porous.whats the easiest way to trace leaks? i have a stethascope but cant hear anything leaking,can i use a food dye somehow?
First off, for that, lose the coupler through the film.
Just use some tacky tape around your hose and use some flow media to make sure you dont puncture the bag.
Ball up the pleats with some tacky tape and it will seal.
I have seen some molds that have had pin holes too! They would place some carbon paper into the mold, bag it and spray it with deluted ammonia to find the mold leaks. Bondline has a special coating for those…
Place some breather in the mold, bag it, vacuum it and then spray deluted food coloring wiht water around to see where you are getting vacuum leaks…
I never had any problems with those thru the bag fittings.
Quick Lock Seals!!! They work incredibly well and you don’t have to worry about buying loads of vacuum bagging tape. Saves me a bunch of money.
http://www.acp-composites.com/acp-vbes.htm
Look close to the middle of the page and you will see the product. You can get them in 72" lengths, I think.
Keep in mind though, you’ll have to order bags. I get 4 mil poly bags, 36" wide from Associated Bag Company. They seem to have the best prices that I can find.
I just throw the whole mold into the bag and it works great!!! I still use the tape and bagging film for larger parts though.
Danny
i will give this a try later,i suppose i can just spray pva as i have that already in a spray bottle.
bingo baby.
Is that the cheaper tape? We use their grey stuff, and it works well even with some wrinkles…just gotta be small enough, and squish it around alot to get it to stick to the bag. Basiclly pressing out the bag winkle, into the tackey tape, and letting it come back up, with tape stuck to it.
I can post a pic later today.
As for the vac port. make sure you have NO NO NO NO wrinkles…you can’t fix it then.
Also, yeah, get some real bagging material. You never know how perfect blown shrink wrap will be.
as hybrid said, if you must, lose the vac. port, and just tackytape the hose right into the bag. Make sur eyou have lots of breather around it, so the bag itself doesn’t get sucked in.
had an idea,if i put the bag as i still have it assembled under water and blow thru the pipe i should be able to see where its leaking 
I tried a stephoscope in the begining what a waste of time that was, so i bought an ultrasonic leak detector, brilliant piece of kit i recomend getting one. I got mine of ebay from a company oop north. If you put it in water dont let any moisture get into the bag. I`m sure i read on this site somewhere that you can use talcom powder dust it around the bag and i suppose the vac would suck some in where the leak was, at least i think thats how it would work.
Baz
i tried talc the other night and i just ended up making a huge mess lol ive just tried it under water,and blew it up,quite revealing! air is indeed pissing out of the connect valve in 2 places and a tint tiny hole in the film but my bagging tape sealed!
so i will see what i can do with the valve and looks like i will have to get some vac film now.
Hell I use the yellow tape from fiberglass supply its cheaply had by the box and I never use the silly thru bag vac ports.
To me, if you puncture a hole in your bag, you start at a disadvantage. That and it almost always leaves an imprint of it in your part. I get enough headache from the stupid lines running in my bag.
When I make pleats, I just cut a small chunk of tape and roll it up and put it in the pleat. It usually seals up.
So the through bag vac fitting was leaking, i bought one of these and tried it once then relegated it to the bin. Do as hybrid says, thats what i do and it works a treat m8.
Baz
not sure im confident on getting it to seal if i just poke the pipe thru the bag?
right ive fixed the valve problem now with some ptfe tape and had another go,this time no leaks and no holes,bagging tape appears to be not the problem i thought it was then i had an idea!
with the posh airtech valve you can disconnect half of it which then perfectly seals the half left on the bag,surely i can just pull the full vacuum,infuse the part,clamp the resin line and then simply disconnect the vac line to leave the bag perfectly sealed forever??? surely it cant be this simple!
yes it is that simple m8 get the seal right and your there. when you say poke the vac line through the bag thats not quite right. What you do is lay the vac line on the bag sealing tape so the vac line is 90 degrees to the tape then take about 2 inches more of the tape and put it tightly over the vac tube and down onto the tape thats already there. I think thats clear. anyway a bit irrelevant now you`ve sorted the leak.
Baz
currently running a test 
both chamber and clipped off bag appear to be perfectly sealed…see if it gets to 8 clock then i will be happy.
do you mean like this but with film over the top obviously? sorry about the crap picture,camera has gone flat.
yes m8 exactly.
Baz
Never had any problems with thru bag ports. Use them all the time in production parts for autoclave cures.
Just NO wrinkles under the port and make sure the hose connection is good also. Use thread tape! Dont tighten down the port until there is vacuum applied. Make sure the seal is clean and there is no fiberglass fibers there.
And the pic of ‘straws’ in the sealant tape…thats a no-no.
If there is a hole in the bag that you find, just put a piece is takcy tape on top of the bag to seal it. It wont mark through.
Bill, if you are refering to gtfours pic above its not a straw m8 it`s 12mm plastic hose, that hose is to draw the vacuum, nothing wrong with that, works just fine. I sometimes use that method amongst others and never had a problem.
Baz
yeah, we just make pleats, with tackytape strips to seal the pleats…it all works.
Our normal vac ports are QC’s with brass tubes, spiral wire inserts to make them flexible in the bag. Only started useing those flat ones since we are starting to make things almost the same size as the oven. Rather have a port that won’t get knocked off on the way IN the oven!
Still, as long as you do it right, anything can work.