I often heard worries in the coffee community about a difference of quality in the coffee grind size distribution when grinding with a full hopper versus a single dose of coffee in an otherwise empty hopper.

The idea behind this is that coffee beans forced through the rotating grinder burrs have no choice but to go through whatever openings they encounter between the burrs. In contrast to this, a single bean in an empty hopper will bounce around and may end up passing through a larger hole between the burrs when the opportunity arises, because nothing is forcing it to pass through very fast. This bouncing around of a bean is what “popcorning” refers to.

As a result of this effect, beans that popcorn will end up getting ground somewhat coarser on average. Grinding a single dose of coffee in an otherwise empty hopper will therefore generate two…