Question: Thanks for your quick answer to a previous question. We finally bought a woodstove and now have a question about the chimney. We heard that some brands of double-walled metal chimneys have been found to prematurely corrod due to cholorides in the silica insulation reacting with moisture creating hydrocholoric acid. Do you know how true this is and if it is a problem, is metalbestos one to avoid? Answer: This was a problem with certain brands of chimney a number of years ago. We have not had any instances of this with Metalbestos in our 6 year history with them.Certain climates, such as humid ones like Hawaii, etc, seemed to aggravate the problem. I think you are OK with most, if not all, brands today.