Sister bought a house. A very old house. Lots of mystery around a whole lot of hidden spaces. No bodies so far, but this was one of the things she showed me and asked if I had any idea what this might be. To me it has the look, feel and thickness of Kapton materials I've used over the years as an electronics assembler. This is a whole dang spool, 14 inches in width and the spool has approximately 3/4 inch of this stuff wrapped around a heavy cardboard spool. What do YOU think it is?