Release Liners: What Are They and Why Do You Need Them?
For tape, because of how it is dispensed, the adhesive part must contact its own backing yet still be able to unwind easily. To achieve this, the backing must provide a low-adhesion release surface. In other words…not stick to itself!
Paper tapes need a coating known as backsize, as well as a low-surface energy coating known as a release coat. Plastic films only require a release coat.
The backing on foam tape won’t allow the adhesive to come in contact with it
For aluminum foil tapes, the act of unwinding it from its own backing will cause it to ripple and distort the foil, which will adversely affect the contact area as well as the appearance.
For all of the above, the best solution is to use a facing material with a low surface energy, usually a paper or a plastic film that has been treated with a silicone release coat. They could also be a polyethylene film that already has a low enough surface energy to work as release facing, or even a silicone-coated polyester film.