A. Even the best of pipes may occasionally turn sour, for some unexplained reason. To make a briar sweet-smoking again, first clean the pipe thoroughly. Then plug the stem with a pipe cleaner, fill the bowl with a good pipe-cleaning fluid from your pipe dealer, and let the pipe stand overnight. Then remove the liquid cleaner, dry the pipe thoroughly and let it stand another twenty-four hours. Now break in the pipe again using mild tobacco.
Extract from Weber’s Book Of Pipes, c. 1962
Pipe Sweetener available here – http://www.eacarey.co.uk/shop/accessories/pipe-sweetener.html