Another Cleanning Method: Fire Cleaning

From time to time, you will probably find that the sheer quantity of tar and other nasty things that have accumulated in the porous material of a clay pipe will result in a much decreased absorbency and thus wetter smokes, complete with the occasional quantity of "pipe juice" coming up the stem and into your mouth. The flavour of your tobacco will be marred, you will often be spitting tar and juices out, and the increased moisture will increase the chances of bite. This is when you need to clean the pipe more thoroughly, and the best method is baptism by fire.

Ideally, if you have access to a gas kiln, either in your own home or through a friend, or even by hiring space at a commercial ceramic supply shop, refiring your pipe is the perfect cleaning. The pipe is placed in the kiln, and heated to a temperature below the one it was originally fired to, but high enough to drive out and burn all the chemicals that have accumulated in the clay (cones 03 and 02 has worked for me in the past, but it is best to consult with someone who knows what they are doing and can judge what kind of firing the pipe originally went through). This is the only way to thoroughly clean your clay pipe, but unfortunately all seasoning is also lost: when the process is finished, the pipe will be almost like new. It will have regained so much absorbency that you will feel it clinging to your fingers and lips when you smoke it for the first time!

As I said, this is the ideal situation, but not everyone has access to a kiln, and of course if you don't have a number of pipes to clean simultaneously it might not be cost effective. There are other methods you might find more convenient:

Putting your pipe in the oven, with the rack as high as possible, then putting the oven on "self clean" can sometimes do the trick. You won't get as clean a pipe as from a kiln, but it will certainly set back the clock. The disadvantage of this if you have an electric oven is that the tars might not actually combust, but simply evaporate, in which case you may end up with a slight residue on the elements and other surfaces in the oven. The effect will only be slight, but you might detect a slight smoke smell while cooking in the future.

If you happen to have a self-cleaning gas oven (I've only ever seen one of these in my entire life - whether they were anything but a failed experiment I don't know), you should have no problem, as the gas burners will consume the residue more completely and drive what is left out through the exhaust. When the self-clean cycle is done, your pipe will be as clean as it can get from this method.

If you have a gas oven with a grill, or a gas barbeque, you can place your pipes as close to the flame as possible, light the gas, close the lid/door and leave it alone for a while. Cleaning will take at least 20 minutes, and may take as long as an hour depending on how hot your grill actually gets. Depending on the arrangement, you may want to turn the pipe from time to time to ensure even cleaning.

A very traditional way of cleaning your pipe, and the only one that actually contributes to the seasoning in my opinion, is to place it in a fire. Carefully arrange your pipe in the fire, then rake glowing coals overtop. (I like to get coals into the bowl, too) Your pipe is now completely surrounded on all sides by burning material. Typically, one will need to leave the pipe in the fire quite some time (I generally just leave it there until the fire burns out) and it won't appear as clean due to the accumulation of soot and such on the outer surface, but a campfire cleaned pipe has a special something about it that needs to be tried to be understood.

This is the riskiest method, in my opinion: manually immersing your pipe in a flame such as that from a Bunsen burner, blowtorch or even the gas burners of your stove or oven. You need to take extreme care not to burn yourself as the temperatures involved are high enough to do some serious damage. Keep a close eye your clothes and other dangling objects to avoid the risk of fire. In all, though, to a sensible person using this method, the greatest risk is not to himself but to his pipe.

If you are not careful to heat the pipe evenly, you will get differential expansion and this may result in cracking or spalling. While the effects may not be immediately visible, small stress fractures within the body of the pipe may make it more and more fragile until at some point it may snap in your hands as you tamp or pack the pipe. If you can't get the whole pipe into the flame, then you should run it smoothly back and forth to ensure even coverage.

While some recommend that you heat the clay until it begins to glow, this isn't really necessary. You will be able to watch the clay get cleaner and cleaner, and if it doesn't seem to be changing at all, simply move it more slowly through the flame to increase the average temperature.