These diamond knife cleaning rods are made from very strong, pressed styrofoam.
1) Bevel the tip of the rod to a 45° angle with an oil-free, clean and sharp razor blade.
2) Dip the bevelled tip in absolute alcohol (ethanol) and shake off any excess.
3) Starting along one side of the knife, pass the rod along the entire cutting edge, applying little or no pressure.
4) Repeat the pass in the other direction, using a different portion of the rod. Marks from each pass should be visible at the tip of the rod.
This procedure can be repeated if necessary.