How do the Pro's grind pepper? : AskCulinary - reddit
White rice. Grind 1/4 -1/2 cup (depending on the size of your grinder) white rice for a minute or so on the finest setting, dump the rice powder and use a damp towel to wipe it out and you should be good to go. The ground rice powder gives the oils left over from the spices something to grab onto. Dump out the powder and the oils go with it.