Hmm... thanks for all this gent's.
Moxon mentions Emerick (emory) and tripoli. Rotten stone I've heard of as a sharpening stone (The Village Carpenter) but not for polishing, but it makes sense.
Thanks for book titles.
Filing can give the desired result for some items but not for others. Burnishing was certainly used as an everyday method to obtain a shine, sand seems to have been more of a monthly thing ot 'whenever it was really needed'.
I have never come across a mention of case hardening with reference to cooking utensils. Please let me know where this comes from.
For the most part, old kitchen kit was made from wrought iron; only the well-to-do merchant / large-scale farmer / squirearchy class and upwards could have afforded steel. The quality of finish, as well as of metal, clearly increased with cost too. There are some superb pieces in the British Museum (as one would expect) but smaller collections interest me more and usually show what someone of the yeoman level would have had - well made stuff, a bit of steel here and there, but mainly wrought iron. The very poor (a large majority) had little access to metal until the early 19th Century, their utensils for the most part being made or wood, bone and horn - very little of which has survived; any iron they had would probably have been of poor quality or suspect origin... unless a gift.