Grinding generates static electricity through friction, and charged grounds repel each other and cling to everything.
When it is worst
Dry air — winter, heating on, low humidity. Light roasts, which are drier and harder. Plastic chutes and bins, which hold charge. Single dosing, where a small quantity of beans passes through a large grinder.
The fix: RDT
The Ross Droplet Technique. Add one or two drops of water to the beans and stir before grinding.
That is all. The trace of moisture dissipates the charge, and the spraying, clinging and clumping stop almost entirely.
It costs nothing, it does not affect the coffee, and it does not damage the grinder — a drop or two on 18 g of beans is far less moisture than the beans absorb from humid air.
Use a spray bottle set to a fine mist, or wet a spoon handle and stir.
What else helps
A metal dosing cup rather than plastic, and grounding it by holding it.
A bellows to puff retained grounds out of the chute.
Anti-static mats under the grinder — marginal.
What does not work
Rubbing the bin, tapping harder, or grinding slower. The charge is generated at the burrs.
The one caution
Do not overdo it. A visible film of water on the beans can cause clogging and, over time, corrosion. Two drops on a dose, not a spray of water.
Last reviewed 8 August 2026