Thread: The Black Polish

Here's the info Oz:

"...BOULDERING STONE. - This name is applied by the Sheffield cutlers to the smooth translucent flint pebbles, found in gravel pits, with which they smooth down the faces of buff and wooden wheels, by abrading any large grains of emery, or other powder contained on their surfaces. [...] The bouldering stones are usually selected of about the size of a hen's or pigeon's egg, and of a flattened form; and the flat side becomes gradually worn down and smooth from its continual application. [...] Metal laps are "bouldered down;" first, they are supplied with a little emery and oil, which is spread with the fingers, and then pressed into the metal and worn down fine and smooth with the bouldering stone, and wood laps are first anointed with flour emery or fine flour emery; they are then well bouldered, and are lastly waxed by holding a small piece of wax against the revolving wheel; these processes greatly reduce the cut of the powders; and unless the bouldering stone is plentifully applied the colour or high gloss cannot be produced on the works..."

In looking for it I also found a bit more about dressing the face of the lead wheel. After the face has been trued, the face is lightly hatch-marked with an old razor. This allows a large charge of emery/polish to be taken up. As the work progrsses, the hatchiing gets smoothed away, leaving the polish embedded in the surface of the metal. In the final polishing, another piece of blade or piece of razor steel is used to scrape the surface of the lead as the wheel revolves, removing a very thin skim of material and leaving hardly any polish at all - at this point powdered charcoal is dusted on the wheel to give the final lustre.

Regards,
Neil.

Wow Neil they really built their gear from the ground up. I'm sure as with Japanese sword polishing all the minerals in the stones etc get impregnated in to the steel giving the 'colour' & depth to the polish. Different ball game to the old Chrome oxide buff.

I think natural emery rock is available thru Indian suppliers but who would go to all that trouble these days.