There are lots of ways to clean a coffee or spice grinder out there. I've previously tried using bread but found it gummed up and wasn't very efficient. I also tried both sugar and salt, but those seemed too fine to really grab all of the oily coffee grounds.
So how do I clean my coffee grinder? A small amount of rice and a paintbrush or toothbrush. Easy! :D
P.S. Don't ever clean your coffee grinder? You should give it a try! The oils from the coffee beans can go rancid over time, so you may be pleasantly surprised at how much better your coffee tastes after cleaning your grinder.
Step 1: Add the Rice to the Coffee Grinder
For most standard size coffee or spice grinders, you only need 1/4 cup rice. You can use any type of rice you want as long as it's dry and uncooked.
If you have a larger coffee grinder, just add enough rice to cover the blades entirely.
Step 2: Grind It Up
Process the rice until it is a fine powder. It should change in color slightly - turning a very light tan.
Step 3: Pour Out the Powder and Clean Up the Grinder
Tip the rice powder into the trash or a compost bin and then use the paintbrush to scrape out any excess powder.
If your grinder is especially stinky (or if you use it for both spices and coffee!), use a paper towel dipped in plain white vinegar to wipe it out. Keep the lid off and let it air dry completely before using again. The vinegar smell will go away as it dries.
And there you go! Enjoy your fantastically clean coffee grinder. :D