What sort of oil is used? And are there conspicuous benefits (observed by you owners) other than bragging rights?
,What sort of oil is used? And are there conspicuous benefits (observed by you owners) other than bragging rights?
Go further, and the idea becomes that the shell patent is the oil curing patent, and the corollary is that smooth pipes were never oil cured. The shell was indeed a "shell" for real, a hard and yet gummy coating (anyone who has ever worked with linseed or tung oil will be well familiar with what happens if a glob dries). All the text in the "About Smoke" catalog would back this up - the smooth pipes were ostensibly all Calabrian briar, Dunhill believing that to be the tightest and least likely to foul, and all the shells (according to the book) out of some fairly poor algerian wood that Dunhill had been sitting on and wondering what to do with. I doubt very much that every Calabrian block produced a smooth, but that's beside the point. As stated, oil curing is a way to stabilize the wood both in terms of flavor and moisture content. Entirely unnecessary if you have well cured wood (the proof being Castello pipes and other good marks which are not oil cured being perfectly acceptable pipes). Pineseed, linseed, olive oil, mineral oil, flax, peanut oil etc have all been used (any decent tasting, hardening oil with a high smoke point, really).
Also, I'd be very curious to see a smooth pipe with the oil cure patent number on it. The innertube number, sure. Any examples?
The passage I find fascinating is this: Lines 1 through about 20 of the 2nd page of the patent. "The result of the treatment is that the grain of the wood is hardened and stands out in relief to a certain degree, but the oil coming to the surface creates an impervious coating. For the purpose of a further treatment with oil it is therefore necessary to remove the impervious coating. This cannot be done in the ordinary manner by "buffing", which simply removes the projecting portions or parts in relief, before the abrading tool reaches the lower portions...."