Grinding
Single dosing a grinder
Weigh the beans for one brew, grind them, and get all of them out. Keeps coffee sealed and makes switching between coffees practical.
- Skill level
- Intermediate
- How long it takes
- An extra thirty seconds per brew
- Equipment needed
- Burr grinder, Digital scale
- Steps
- 4
Why it works this way
The alternative to keeping a hopper full of beans on top of the grinder. Single dosing weighs out one brew at a time, which keeps the rest of the bag sealed and lets you run several coffees without cross-contamination. It also exposes retention: with a hopper, the coffee that stays behind is replaced by identical coffee and nobody notices, whereas single dosing makes every gram left inside a gram missing from the dose. That is why single dosing and purging are usually learned together.
What you need
Required
Helpful, not essential
How to do it
Weigh the beans for one brew into a cup.
This is the dose you intend, and it is not necessarily the dose you will get.
Add them to the empty grinder and grind.
Some grinders benefit from a light tap or a bellows puff during grinding to help beans feed.
Clear the chute with a bellows or brush.
This is where the retained grounds are, and where the missing grams come from.
Weigh the ground coffee, and adjust the input next time to hit the dose you want.
If 18 g of beans yields 17.6 g of grounds, weigh 18.4 g in. Retention is fairly consistent for a given grinder.
How to tell it worked
Doses that land where you intended and coffee that tastes of the bag you opened rather than of the one before it.
If it did not work
What you saw, what to change, and why the change works.
Beans stall and will not feed into the burrs
Change: Tap the grinder, or use a bellows to push them down.
Without a hopper's weight above them, the last few beans can sit above the burrs.
Output is consistently several grams short
Change: Clear the chute more thoroughly and consider whether this grinder suits single dosing.
Some grinders retain far more than others; it is a property of the design.
Grounds fly out of the cup with static
Change: Add a few drops of water to the beans before grinding.
A very small amount of moisture reduces the static charge grinding generates. This is widely used and is known as the Ross droplet technique.
Common mistakes
Weighing beans in and assuming that is the dose
Every brew is short by the retained amount.
Instead: Weigh the grounds.
Diagnose a specific problem
The science behind it
- Retention (grinder)
Leftover grounds from a previous grind still sitting inside the grinder, mixing into the next one.