With the help of a fellow woodworker, I've found the OEM source for the most incredible vacuum sealing tape available. This is not a knock-off. This is the same high density on-board gasketing tape included with dedicated high-end industrial vacuum clamping systems such as those from ShopBot, C.R. Onsrud and Holtzer.
The tape is coated on one side with an acrylic pressure sensitive adhesive. The foam's 1/4" (0.25") thickness assures conformability to a wide range of substrates and its 3/8" width allows a tighter radius for small parts from the substrate on your CNC router or vacuum clamping/templating jig.
What Is it Used For?
If you are making your own vacuum frame press, this is tape that is used to seal the frame to your workbench. Here are some of the benefits of using a frame press instead of a vacuum bag.
Review by Brian Vaillancourt
I have used this 3/8 x 1/4 vacuum gasket tape for a couple dozen projects to date. I built a 3'x5' vacuum frame press based on Joe's design (I went with 3/4" melamine for the base layer) and used this tape direct to VS Polyurethane material, in two rows. No leaks, and just as good as new now. Don't forget the 0.061" breather mesh for both sides of your work piece, especially for flat projects.