We just installed a wood stove in our old fireplace and this thing worked! We used it to seal all the flexible duct connections to the oven itself. There were no concerns about air leaks. Overall the product has worked great so far. When we applied it, after a day it was hard and the oven was ready to use. I've read other reviews that say you need to reuse the product after a year, so I plan to check it out and get back to you. But all in all this is a great product.