On a recent vacation to New Hampshire ( Jackson, in the White Mountains - unbelievably beautiful ), I came across a product in a mom and pop hardware store called 'Mid-Maine Creosote Sweep". It's a black powder that you sprinkle 1/2 a cup on hot coals twice a week to lessen/prevent creosote buildup on your chimney liner? Has anyone heard of this or a similar product? Any positive results- or just snake oil?