The same coffee, ground on three different settings. From left: coarse, medium, fine.

Matt Roney | Contributor

Welcome to the first entry of The Barista’s Kitchen, a series of posts each focusing on a different technique or piece of equipment accessible to the home-based coffee enthusiast.

It’s my goal not just to help home baristas make the best coffee they can, but to introduce ways in which one may tweak and play with the brewing process, so that each cup can reach its fullest potential.

In general, it’s the brewing methods themselves that get the most attention. An espresso machine is sleek and flashy; a French press, elegantly simple; and a vacuum pot arcane and interesting.

There are, however, a few essential pieces of equipment that often go overlooked. One is the gram scale — any serious coffee hobbyist should have one, as it’s the only way to ensure correct bean dosing. Another is a nice water filter — I’ve yet to find a coffee that goes well with chlorine.

The most important piece of equipment, though, for anyone genuinely trying to brew great coffee, is the grinder.

It’s common sense that coffee ground immediately before brewing will be fresher. Part of the reason is a process called oxidation, which causes it to go stale. When it’s in its whole-bean form, coffee is better protected from oxygen. Also, many of the gasses that give coffee its aromas and flavors dissipate over time, and increasing surface area by grinding speeds up the process.

But it’s not just a question of freshness. How coffee is ground is one of the major factors determining the effectiveness of extraction — basically, how much of your beans’ oils, solids and gasses make it into the cup.

A cup that’s been over extracted is said to taste bitter, while one that’s under extracted tastes sour. A perfect cup of coffee requires that the grind and the dose — as well as other factors, such as water temperature — work together to achieve the right extraction.

The finer the grind, the greater the surface area, so more compounds will end up in your cup with a fine grind than with a coarse one. Plus, water will flow more slowly through a fine grind than a coarse one, picking up still more compounds along the way.

A good grinder will give you a consistent, even grind at any setting ranging from very coarse to very fine. Unfortunately, though, the most common home grinders — the “whirling blade” sort — just aren’t up to the task. The grind tends to be very uneven, which will lead to a very uneven cup of coffee.

Remember, different coarsenesses lead to different extractions, so, if a lot of your grounds are very fine while others are very coarse, you risk a cup with traces of both bitterness and sourness. It’s not appetizing. Plus, the blades often spin fast enough to actually burn your grounds. And after the roaster worked so hard!

There are alternatives, of course. For the home, the most practical coffee grinders both for consistency and affordability are burr grinders. Rather that chopping your coffee with one fast blade, they actually crush the coffee between a hard surface and a rotating wheel covered in sharp "burrs."

Hand-powered ones like this travel burr grinder are quite inexpensive, while electric ones tend to start around $100, like this Capresso Infinity. Either will do the job, and you’ll immediately find your coffee improving.

Matt Roney is a barista at lab cafe and a contributor to Radio Free Chicago. He can be reached by email here.