Dressing (sharpening) the millstones at the Old Stone Mill in Delta Ontario.
Roland Tetrault, master miller, teaches volunteer millers Art Shaw and Chris Wooding how to dress (sharpen) the millstones. Although the stones are made of burhstone, a hard silicious (quartz filled) rock, the grooves in the stones, which provide the cutting surface for the grain, wear down over time.
The trick is that the grooves have to be re-established while maintaining the flat surface of the stones. A board with a coating of wet red ochre is used to highlight the high spots on the stones and it is these spots that are re-grooved.