Perfect product for what I had to used for.

Exactly what I needed for furnace heat exchanger reassembly.

The thermal conductivity is specified as 0.58 BTU/in/hr/sf/F at 1000F. It is listed as 10 PCF density. I couldn’t tell you what the thermal conductivity is at other densities, but that’s the value I found digging. I use this stuff and other related stuff on a 3D printer that I use with polycarbonate filament. Roughly speaking that’s 5600 BTU/hr per square foot with 1/8� thick with a 1350F EGT and 150F ambient. One way to deal with the fragility is to cut curved panels designed to follow the contours of pipes with bends, meeting with other pieces and wrap two or more non overlapping layers with scraps of copper wire until you’re ready cover it and lace it with stainless wire or whatever you were thinking. It’s good to higher temperatures than your exhaust will ever see (melts at 2150 I think).

Cannot check the technicall properties, however, its easy to cutt with scissor and I bonded with 3m fire barrier. Worked great for my needs at the firewall. Searched on the web and call the factory to know which side, but its only part of the manufacturing process, so any side is the same. I used the cloth style on view.

This is a great material for heat proofing a cowl that is close to the exhaust system. I put some on a Super Decathlon and a PA28R-201. No worries about the paint bubbling again. I used 3M 1300L Scotchgrip to attach the Fiberfrax material then spray painted it silver and sealed the edges with silicone sealant. The paint helps reflect the radiant heat and keeps the material from absorbing oil or fuel. Try it, you'll like it.

I didnt test thiis for fire resistance so I cannot rate that aspect of Fiberfrax. However, Im writing this to advise potential buyers of two characteristics. Fiberfrax will tear easier than a sheet of paper and wont tolerate working around on into tight spaces. Secondly the patterns are different from one side to the other. This is only a problem when trying to efficienly utilize the material. Because ACS fails to provide a detailed description of most of their products the only way one would know such things is to waste $50 such as I did or hope someone has provided details in a review.