A Short Guide to Grinding Coffee

I want to up my coffee game. I know that buying whole bean coffee is better, but I’ve never ground my own coffee at home. I bought a package of fresh roasted bean. What do I do next? Do I just toss my newly bought beans in a blender and hope for the best?

While there are many things that can improve a brew at home, grinding coffee correctly for the chosen brew method is among the top. There are two things needed to do to manage this process.


First, grind the coffee to the correct particle size.

Second, make sure the coffee is grinding consistently, each particle the same size as the next.


Why is the grind important? The quick and dirty explanation is this: the process of brewing coffee is simply combining water and coffee, extracting the correct amount of water soluble pieces of the roasted coffee bean i.e. dissolving the coffee in the water. If the contact between bean and water is short, the coffee particles need to be more fine to allow for faster extraction. If contact between bean and water is long, it is better to have a coarse grind, limiting the speed of extraction. Examples: a French press allows the bean and water to be in contact for an extended period of time. Therefore, it is best to use a coarse grind on a French press (also allowing the filter to catch the grounds). While making a pour over, the water is in contact with the bean for a very short period of time - often just seconds. The bean should be ground fine to allow for quicker extraction.

If the water touches the coffee for a short period of time, it needs smaller pieces to dissolve. If the water touches the coffee for a longer period of time, it needs larger pieces because it has more time to dissolve the coffee.

Why does a more fine grind lead to quicker extraction? If water ran through a filter full of whole beans, the water would extract or dissolve very little. This is because the outside of the bean is hard and dense, the water moves through the larger pieces very quickly, and the total surface area that the water touches is small. So the more fine the grounds, the more surface area of that bean is exposed, allowing more of the coffee product to quickly dissolve. The trick is to avoid both under-extraction and over-extraction. An over-extracted cup of coffee will taste harsh and bitter. An under-extracted cup will taste weak and watery.

A well extracted cup of coffee can be accomplished by first, selecting a grinder. This will fulfill the second of the two criteria listed above.


Grinders

There are a number of different grinders on the market. But a simple breakdown yields two different categories. There are blade and burr grinders.

Blade

Blade grinders are basically coffee blenders - cheap and adequate for a price conscious consumer. They are a great entry point for coffee lovers because they allow for freshly ground coffee with some versatility on grind size. But if a buyer has a few extra bucks to spare, it might be worth looking at burr grinders. The whirling blades slice the beans, and the only way to control the size of the coffee particles is to run the grind cycle slower or faster. This leads to a lot of inconsistencies with the final product. The end of the grind cycle will yield both fine and coarse particles, which can lead to over or under-extraction. And the lack of uniformity in particle size prevents you from grinding the coffee fine enough for espresso or coarse enough for a French press. Not only this, but if you run the cycle too long, the blades can become hot and scorch the coffee!

Burr

There are actually two different types of burr grinders. A standard burr grinder (also called a flat burr grinder) leverages two disks to smash and crush the beans into a uniform pieces. The conical burr grinder does virtually the same thing, but the beans enter the burrs vertically through a conical set of teeth. A lot of people argue that the conical burr grinder has a cooler grind, eliminating the likelihood of scorching the bean. They will also say that the conical grinder takes less maintenance and effort to get a consistent grind. While probably true (the conical burr grinder tends to cost more), both will do the job well in a home setting. In both cases, the greater the separation between the disks, the larger the grind size, allowing the user the ability to quickly adjust to different modes of brewing. The uniformity of the grind will make it much easier to brew any style of coffee, meeting both of the grind requirements we stated above: correct size and consistency.

In my personal experience, the biggest benefit I received from having a burr grinder was the ability to consistently brew a variety of different methods. I’ve experimented with the French press, the pour over, and espresso at home, simply because I chose a good grinder for my coffee.

Once a grinder is selected, the only thing left to do is select a brew method and grind level.


Grind Size

Coarse

Cold Brew, French Press - Very similar to the size of chunky sea salt. The particles of coffee are distinguishable and large.

Medium Coarse

Chemex - The coffee is gritty and the individual pieces are still mostly distinguishable. Close to the size of coarse sand.

Medium

Drip Brewers - A texture similar to rough, normal sand. Particles approximately table salt sized.

Medium Fine

Pour Overs - Should be difficult to differentiate between individual pieces of coffee. Much smoother texture. Slightly more fine than salt.

Fine

Espresso - More fine than granulated sugar, though more coarse than flour. Almost impossible to see an individual piece. Smooth to the touch.

Very Fine

Turkish - Close to four consistency. Powdered.

The most important part about the grind level is tweaking it to taste. As mentioned earlier, if you notice the coffee tasting overly sour, acidic, or salty, the coffee is likely under-extracted. The next brew should have coffee particles slightly more fine than the last. If the coffee is tasting bitter or hollow, it is likely over-extracted. This would imply that the coffee was too fine, and need to be more coarse on the next brew.