For many years, it’s been almost an article of faith that pipe smokers should smoke their pipes all the way down to the bottom of the bowl – that is, finish all the bowl of tobacco. The reasoning behind this belief is that smoking to the end of the tobacco develops a well-formed cake (carbon lining) on the interior of the bowl. Partial smoking, it’s said, will leave a cake only on the upper part of the bowl and result in a harsh-tasting pipe. Also, finishing the bowl of tobacco to the bottom prevents burnout, and leaves you with a pipe that smokes cooler and smoother.
That’s what many pipe smokers, myself included, were taught. Recently, though, the validity of this bit of conventional wisdom has been called into question. Writing in the North American Society of Pipe Collectors’ journal, The Pipe Collector, longtime pipe smoker Steve Fallon asserts that pipe smokers should call it quits when they’ve consumed around two-thirds of the bowl of tobacco.
Mr. Fallon explains that the remaining last third of tobacco will have absorbed all the leftover moisture and tars, and turn into a nasty bit of sludge. Continuing to smoke, he says, will leave much of that muck in the bottom of the pipe, waiting to intermingle with the next load of sludge from subsequent smoking. The pipe will also require more frequent relighting, due to the moisture in the remaining tobacco.
Better to smoke your pipe as long as it tastes good, and stop when it doesn’t, roughly at the point at which two-thirds of the tobacco has been smoked. Later, when the pipe has gone out and cooled down, the dottle (the remaining tobacco) can be dumped before it has a chance to foul the pipe. Mr. Fallon then recommends taking a piece of facial tissue or paper towel and twisting it down into the bottom of the bowl for a quick cleaning, along with the usual pipe cleaners run through the stem.
I usually follow this procedure, since I smoke aromatic tobaccos and they have a high moisture content; I've not noticed undue damage being done to the bowls of my pipes. Smokers of "English"-type blends (non-aromatic blends) generally find it easier to finish the entire bowl.
Fallon, Steve. "Another Smoking Controversy?". The Pipe Collector, volume 10, number 6 (December 2002), pages 20-21.