n0legs":3hvbfvz8 said:
What would the old masters have used ?
Before the introduction of man-made stones in the 1890s, UK craftsmen mostly used (imported) Turkey stones; Benjamin Seaton's tool chest (1797) contained Turkey sharpening stone and slipstones. Charnley Forest stones were also prized for the fine edge they gave, though they were slow cutting. There were quite a few other natural stones that would sharpen edge tools, some of them very slow-acting (several varieties of Welsh 'slate' - some of which are not technically slate, for example), and various imported stones (American Washita and Arkansas, for example). The variety was considerable, and the sharpening properties very variable. Some were very highly prized.
The introduction of faster-acting and more consistent man-made stones was greeted, after initial slight scepticism, with some enthusiasm. The formerly prized natural stones became, to all intents and purposes, valueless. There's an excellent account of this in Walter Rose's 'The Village Carpenter'.
In other parts of the world, practice tended to be dictated by the local availability of suitable natural stones. Thus, North American practice revolved around stones sourced from the Washita and Arkansas areas (and to some extent, still does); in Japan, stones that responded well to water as a lubricant influenced their working tradition, and whilst many of the stones used are now man-made, the tradition is still strong. I'm not too sure about the rest of Asia, Africa or even Continental Europe, but I suspect the same applies.