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What is the best way to seal a heavy duty plastic garbage bag to use as a vacuum bag? I have a vague recollection that some kind of putty can be used, but I do not know what kind.

thanks

I don't know the exact name/product spec, but I use 'mastic tape' which is sold in (some) building supply places for glazing work-applied to the window frame and the glass is pressed against it. It comes in a roll- the mastic strip is about 1/2" wide and 1/8" thick, with paper backing along the mastic strip.
It's real 'sticky stuff' and handy around the shop for other uses as well .....(a dab on the end of a screwdriver will hold the screw/bolt in place, etc...)
It's quite cheap.
I believe other folks have just folded the bag end around sticks and used spring clamps, but the mastic will seal around a hose if you are using a makeshift setup (as I do).

Cheers
John

One of the products I use for sealing when doing quick-and-dirty vacuum bagging is Frost King Fingertip Rope Calk. It is like the mastic tape listed above, only the 1.25" tape is made of 8 round cylinders about 3/16" diameter. You can use the full width tape, or you can pull off just a couple of the ropes. This stuff is cheap, seals good, and never drys out.

If you are bagging small stuff, try using a ziplock bag. cut a small hole to stick your vacuum line in, seal it with rope calk. Then lay up your project, stick in in the bag, zip it closed and start the pump.

-jd

If using a regular garbage bag, I have a perforated hose I use for getting vacuum in (so it won't self-seal). I toss the hose in, pull the bag around it, and put three zip ties on it.

Works like a charm!

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services