You must think we just go on and on about grinders, and maybe we do — but with good reason! Your grinder is your best friend when it comes to coffee, whether it’s just a habit or a full-fledged hobby. Making sure that best friend is well cared for and happy is the best way to guarantee delicious coffee every day.
Sometimes your best friend can’t tell you exactly what’s up when something’s feeling off, so it can be helpful to know a few signs and clues to help you identify and fix what might be going wrong. Let’s take a look at some of the common trip-ups you might run into together.
Do you pre-measure your whole-bean coffee before running it through the grinder? Then you might notice that your finished dose comes up a little short. It’s not you, and it’s probably not your scale: It’s most likely the grounds retention on your grinder.
Even the best grinders on earth will often “eat” a little bit of coffee without meaning to: There is usually a space between the burrs and the dispensing chamber where the last few grounds will get stuck. Since coffee beans move through burrs with the force of gravity, the beans on top help push the beans on the bottom — but when you reach the end of the dose, those last few don’t have anything to push them through. So they get stuck like Gilligan & Co., abandoned until the next time you grind coffee.
While you can’t change the design of your grinder to prevent this problem, there are a couple things you can do to prevent it from impacting your cup.
First, purge your grinder by running just a few (say, five or six) beans through it before you start. This will push out any of the old, stale coffee that is stuck in there and will prime your grinder for the fresh coffee you’re about to prepare.
Next, up your dose just a little bit. I always weigh my whole beans as well as my grounds, and it looks like my grinder retains about .02 grams of coffee on average — just about one bean’s worth. The simplest solution is to add a bean or two to your dose, so you’ll be closer to spot-on when the coffee is ground.
Speaking of losing coffee, there’s nothing worse than grounds flying everywhere due to static, which not only makes a mess but can also affect your coffee ratio. Static electricity is created by the friction of grinder burrs against beans, which changes the charge of atoms in the coffee grounds and causes them to become imbalanced, requiring a release of energy in order to lay “at ease.”
While static is a natural fact and can’t be completely eliminated, there are a few different ways you can control it a bit better.
First, try grinding into a non-plastic container: Metal conducts electricity, while plastic insulates it, and you want conduction in order to create a re-balance of the charges. Second, don’t rush: After grinding, let the coffee sit for a moment or two in the container, and then give it a good tap or two on the counter or with your hand. You’ll usually see that the coffee will settle itself down if you let it have a little time.
The most controversial technique is called the Ross Droplet Technique (RDT), a hack that was introduced to coffee nerds in the early days of Internet home-coffee forums. Credited to David Ross, RDT uses the conductive property of water to eliminate static before it’s created. By adding the tiniest amount of water — and we mean tiny, no more than one drop! — there isn’t the same buildup of imbalanced charge, and the coffee grounds should fall easily to the bottom of your dosing chamber.
(Note that this only works with single-dose grinding: Don’t add water to a full hopper of beans. And you never want to get your grinder burrs wet, so when we say to add “the tiniest amount of water,” we mean it!)
Hot coffee grounds
If you notice that the coffee coming out of your grinder is very warm or even hot to the touch, it’s probably time to consider cleaning and/or changing your burrs. Friction creates heat, and grinders create friction, but when your burrs are dirty or dull they will create even more, which will raise the temperature of your grounds and can cause a bitter, over-extracted-tasting brew.
When your burrs haven’t been cleaned in a while, there’s a chance they’re coated with a film of coffee fines, or coffee that’s ground so finely it’s practically powderized. This film of powdered coffee will then be coming into contact with your fresh beans and grounds, increasing the friction created in the grinder and causing them to warm up. You can remove fines from grinder burrs either by (carefully!) disassembling the burr set and cleaning them manually, or by running a cleaning tablet or dry grain such as uncooked rice or pasta through the grinder.
If you clean your grinder and you’re still finding that the coffee coming out is noticeably warm to the touch, it might be time for new burrs altogether: Remember that most burrs are made of machine-cut metal and will become duller over time with repeated use. As they become dull, you’ll probably find yourself adjusting the grind size finer in order to achieve the same effect as before, when they were sharp. The finer your grind setting, the closer the burrs are to one another, and when they are very close together they will create more friction and retain more heat than if there is a bigger space between them.
Many grinder manufacturers sell replacement burrs, and if you’re using your grinder daily or multiple times daily, you may want to look into a new set every year or so. If your grinder doesn’t have the option to swap out the burrs, you may want to consider replacing it for one that does: We love the Ode grinder from Fellow and the Encore from Baratza, both of which can have their burrs replaced without chucking the whole machine.
Lots of fines and/or very slow draining
Similar to the above, if you notice that the coffee left over in your filter after a brew looks more sludgy or muddy than it used to, or if the brew itself is suddenly taking a very long time, you may also be seeing signs that it’s time for a burr switcharoo: Dull burrs have a greater tendency to create an abundance of fines, which will absorb and retain water quickly and can clog or slow the flow of water through the grounds and filter.
Can’t replace your burrs right away? You can try to grind slightly coarser and slow the flow of your pour through the grounds in order to compensate, or consider buying a sieve that can help you sift out the fines. While neither solution is as completely effective as changing the burrs, they can be an inexpensive quick-fix until you’re able to invest in new parts or equipment.
Remember that your grinder is your bestie and treating it well will have delicious and caffeinated rewards — even if it can’t lend you its car or watch your cat while you’re on vacay. (Hey, you’ve gotta make other friends, too!)