The Norton Flattening Stone is the new low-cost way to flatten waterstones. The coarse silicon carbide grit with diagonal grooves quickly flattens waterstones. Uses Due to their tendency to wear concave, finding a good way to flatten your waterstones is critical. Simply rub this stone on your waterstone with plenty of water until the waterstone is completely flat. If flattening is done on a regualr basis, this process is very fast and keeps your stones ready to use.