Zassenhaus publish the following Care Instructions including how you should clean the Zassenhaus Coffee Mills:

The correct maintenance of your coffee and corn mills

You should clean your mills at least once a year because in the course of time oil contained in every coffee bean settles on the grinding mechanism. If the oil becomes randic (eg on warm days) the freshest coffee no longer tastes good. An intermediate cleaning restores a tasty coffee flavour.

Express cleaning

Grind a small amount of raw peppercorns or uncooked rice. This dissolves oil residues of coffe in the grinding mechanism in the best and most eco-friendly way. Grind some beans afterwards and the mill is now ready to prepare aromatic coffee and espresso