A year ago I installed a wood-burning fireplace insert and depended on it totally for heating our home. I was amazed at how efficient the stove is, but now there's a problem. The lower part of the chimney near the stove is coated with a black glaze which I cannot remove with a scraper or even with a torch. I'm told that it can be dangerous. Do you know of a chemical that can remove the glaze and prevent it from building up? Don Hathaway Mechanicsville, Va.
You're probably talking about a buildup of creosote which can take many forms. If allowed to remain in the chimney, it can cause a serious fire hazard which, of course, you do not want.
There may be a draft problem which should be corrected.
If the creosote were crumbly you could remove it with a chimney brush. But you say it is hard and resists removal with a scraper or even a torch. I do not know of a chemical to do the job.
You should call a chimney sweep or chimney-maintenance firm (check the Yellow Pages) and get after the problem right away. You don't want to risk a chimney fire, which can be a frightening experience to anyone in the house at the time.
Also, it can result in severe and costly damage to the chimney and even threaten the house itself.
Regular chimney upkeep should not be neglected. It's always cheapest in the long run.