I am not certain what barrier foil may be, exactly, although occasionally in our museums we use household, heavy-duty aluminum foil as a barrier layer. It is not especially tough, and will not take much physical abuse. For that reason, Marvelseal 360 (or the heavier 470) is a good choice. We bought a roll from a wholesale vendor, at significant cost. Gaylord Brothers, the archival vendor, sells 50-foot rolls of either variety, which is about the smallest quantity I have seen on sale. The cost is about $150.
