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When you are researching a subject every once in a while you run across quirky little bits of information that are not all that pertinent to our study of history but it does answer a question sometimes not even asked. I found this bit of information when doing research for an article on buff leather. It seems there was quite demand for surplus buff leather to be used for polishing and sharpening. Ken Knopp and I are working on this article that will answer a few questions about buff leather. This was published in a sportsman magazine in 1803.
A common knife-board covered with thick buff leather, on which is put emery one part, Crocus Martis three parts, in a very fine powder mixed into a thick paste with a little lard or sweet oil, spread on the leather the thickness of a shilling, gives a far superior polish and edge to knives; and it does not wear the knife a quarter so much as the common method of using brick dust on a board. These buff-leather boards with emery and crocus martis are sold at 10s. 6d. each in London, under the presence that something more than emery and crocus martis is used. This is also the great secret for taking out notches from pen-knives, giving razors a superior edge, & c.
Crocus Martis: A polishing powder consisting of iron oxide.