I started using these late last winter on a (new to me) stove and chimney that had not been cleaned recently. I didn't see much difference, but I swept the chimney and scraped the inside of the stove during the summer and have been using them this winter so far. Really seems to help keep the creosote build up down and what does build up in trouble spots inside the stove comes off really easy. The chimney seems to be staying a lot cleaner than it normally would be. I do burn a lot of pine, but mostly cedar.