Ground coffee flies everywhere with static
Grounds cling to the chute, jump out of the cup, and scatter across the worktop.
Applies to: Espresso machine, V60 (pour-over), Espresso, Filter coffee
Why ground coffee flies and clings
CoffeeHQ explanation
Breaking a coffee bean apart and dragging the pieces across metal burrs separates electrical charge, the same way a balloon picks it up from a jumper. Each particle leaves the grinder carrying a charge. Like charges repel, so light particles and flakes of chaff spray outwards instead of falling, and charged particles stick to the chute, the cup and the counter.
Published measurements of coffee grinding found that moisture governs how much charge builds: beans with more water in them charge less, and a small amount of water added just before grinding reduced static markedly. That fits what people notice at home. Static is worse in dry winter air and with central heating, and often worse with darker, drier roasts.
Causes, most likely first
There are 3 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 3 · Commonly the cause
Static charge generated during grinding
- What to change
- Grind into a dosing cup first and let it stand a moment. Some people also stir a drop or two of water through the beans: in one study a small amount cut the charge by at least half, and it changed how a dark-roast espresso ran. Whether water belongs in your grinder is for its maker to say.
Cause 2 of 3 · Reported, not independently verified
Dry air, which makes static worse
- What to change
- Expect it to be worse in winter and in heated rooms.
Cause 3 of 3 · Commonly the cause
Grinding into an open basket rather than a cup
- What to change
- Grind into a dosing cup, or fit a dosing funnel to the portafilter.
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.
- Grounds cling, jump and scatter with staticThe possibilities, the quickest check and one thing to change first
Add a trace of moisture, or give the grounds a moment
Wet the handle of a teaspoon, shake it off, and stir it through the weighed beans before grinding. That is all the water the method needs; visible wetness is too much. Check the grinder's manual first, since a few manufacturers advise against it.
If you would prefer to add nothing, grind into a closed container or a dosing cup and leave it for half a minute before opening or tipping it. Charge leaks away quickly, and coffee that has rested for a few seconds behaves far better than coffee caught as it leaves the chute.
Easily confused with
- Clumping — The same charge that scatters loose grounds binds packed ones together. Reducing static usually reduces both, but clumps also come from oil and from the chute.
- Retention — Static holds grounds inside the grinder as well as outside it, so a sudden rise in retention on a dry day is often static.
What not to change at the same time
Do not add moisture and alter the grind setting together. Damp beans grind slightly differently, so confirm the shot time at the old setting before adjusting.
How to tell it is fixed
Grounds fall straight down into the cup or basket, the chute stays largely clean, and there is no halo of chaff on the counter.
If that changed nothing
If static stays severe with a trace of moisture, check that the grinder's outlet and any anti-static flap are clean; packed fines there generate and hold charge.
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.