Your questions sent us on an interesting journey, starting with the manufacturers of woodstoves and chimneys, and venturing along the way into the art of chimney sweeping and the science of chemistry. First, the chemistry.

The main entrant in this category, or at least the most advertised one, is The Chimney Sweeping Log. On its website, the log's manufacturer explains that "specially developed minerals," dispersed as the log burns, cause a catalytic reaction that makes creosote deposits become brittle. Heat from subsequent burning causes the creosote to break away and fall as small particles.

There's nothing wrong with the science of this, says Ray Bonar of Industrial Chimney Company in St-Jérôme, Que., which makes insulated stainless-steel chimneys. In fact, when they find a badly gummed-up chimney, professional sweeps sometimes use a chemical spray or powder - the active ingredient is usually manganese - that does the same thing, turning hard-glazed or sticky creosote deposits into softer, more friable deposits that are more easily swept out.

As for the product's safety, there's nothing inherently dangerous in burning the logs in either a fireplace or a woodstove, says John Gulland, a wood-heat consultant for the Canada Mortgage and Housing Corporation, and the author of the CMHC's A Guide to Residential Wood Heating. What could be dangerous, though, is assuming that by burning the logs, you can avoid a mechanical chimney cleanout. The maker claims the small particles of creosote will "fall into the fireplace," which assumes a straight chimney flue directly above the combustion chamber, with nothing in the way - a setup Gulland says he can't even imagine. Virtually all wood-heat systems have a baffle or damping device above the combustion chamber, and flues often have bends or are offset. In fact, part of a professional chimney cleaner's job is to make sure fallen-down soot and creosote is removed from these spots, and anywhere else it could cause a flare-up. In fairness, the website for The Chimney Sweeping Log does say that burning the log does not replace the need for regular, professional chimney inspections. That being so, Gulland wonders why a cottager would even bother with the logs.