I caught about 10 minutes of Ask This Old House this last weekend and saw something I'd like to try and find. I cant recall if it was Tommy or the plumbing guy (forget his name) that was helping someone install a new radiator in a bathroom. When it came time to solder the copper pipes, they had a piece of white woven material they put behind the pipe that kept the torch flame from catching fire to the joist behind the pipes. Anybody know what this stuff is called and where to get it? At some point in the future I have to redo a short section of pipe running to the water heater and it's about an inch from the joists. That stuff looks like it would work great.