The shot changed unexpectedly after a grind adjustment
A small grind change produced no effect, or a much larger effect than expected, or the effect arrived a shot late.
Applies to: Espresso machine, Espresso
Why the first shot after a grind change misleads
CoffeeHQ explanation
A grinder never empties completely. Some coffee stays in the burr chamber and the chute after each dose, and it was ground at whatever setting the grinder was on at the time. When you change the setting, the next dose is a mixture: part old setting, part new. The shot it makes tells you about the mixture. It is common for that shot to barely change, and for the one after it to jump further than expected.
The second cause is the other things that changed without being decided. Coffee a day older resists water a little less. A machine that has been on for an hour is hotter than one switched on ten minutes ago. Beans taken from the freezer grind differently from beans at room temperature. Each is small, and any of them can be mistaken for the effect of a one-notch grind change.
Causes, most likely first
There are 4 likely causes, listed with the most probable first. Work down the list and change one thing at a time, so that when the problem goes away you know which change fixed it.
Cause 1 of 4 · Commonly the cause
Retained coffee at the old setting
- What to change
- Purge after every adjustment; the first shot afterwards is a mixture of two settings.
Cause 2 of 4 · Commonly the cause
Two variables changed at once
- What to change
- Return to the previous setting and change only one thing.
Cause 3 of 4 · Reported, not independently verified
Coffee ageing between sessions
- What to change
- Expect to re-dial as a bag ages, particularly in the first weeks after roast, while it is still losing gas.
Cause 4 of 4 · Reported, not independently verified
Beans switched between frozen and room temperature
- What to change
- Grind consistently from one state or the other; frozen beans fracture differently.
If none of these fixes it
Check the cleaning and descaling guide. Equipment that needs maintenance can cause several of these symptoms at once, and no change of recipe will correct it.
Work through it for your setup
The causes above are general. These go to the part of a diagnostic that takes this symptom one check and one change at a time.
- Less coffee comes out than went inThe possibilities, the quickest check and one thing to change first
- The same setting gives different results from day to dayThe possibilities, the quickest check and one thing to change first
- Dialling in espresso: the workflow
Purge, then judge the second shot
After any adjustment, run a few grams through the grinder and discard them before dosing. How much depends on the grinder: single-dose designs hold almost nothing, while grinders with a long chute and a hopper can hold several grams. Then pull the shot, and treat it as provisional. Make your next decision on the shot after that, at the same setting.
Easily confused with
- Retention as a standing problem — Retention is the mechanism. This is its most visible effect: a shot that does not match the setting you just chose.
- Coffee that is ageing — If shots speed up gradually over days at an unchanged setting, the coffee is the cause and the grinder is innocent.
What not to change at the same time
Do not change grind and dose between the same two shots, and do not change the grind twice before tasting a purged shot. Two unread adjustments in a row is how a dial-in gets lost.
How to tell it is fixed
Two consecutive shots at the same setting land within a second or two of each other, and a one-step change moves the time in the direction and by roughly the amount you have come to expect.
If that changed nothing
If consecutive shots at one setting still wander by many seconds after purging, the variation is coming from the dose or the puck. Weigh the grounds in the basket for the next five shots before blaming the grinder.
Espresso dial-in assistant — Enter the two shots either side of the adjustment. The assistant names the one change it would make next and what must stay the same while you make it.
Related issues
Work it out
Interactive tools that take you through this one change at a time.
Learn the technique
Step-by-step guides to the skills this problem comes from.
- Adjusting grind sizeMove the grind in the right direction by a useful amount, and know what to expect from the change.
- Purging a grinderClear coffee left inside the grinder so the next dose is the coffee and the setting you intended.
- Storing and freezing coffeeSlow staling for coffee you will drink soon, and slow it further for coffee you will not.
- Resting roasted coffeeLet a fresh roast settle to the point where it brews predictably, without waiting until it has gone flat.