Learning to read the cup: why flaws matter more than grades

When we talk about specialty coffee, we usually focus first on the notes: cherry, cocoa, white flower, black tea. That's normal. They're the most visible part of coffee's language. But if you want to make better coffee at home, there's something much more important to learn first: recognizing defects.

Because a cup might have "notes of red berries," but if it's dominated by aggressive bitterness or a dry astringency, that information is of little use. The first thing is to understand if the extraction was done correctly. Then there will be time to refine the nuances.

The cup as a diagnostic tool

Thinking of coffee as a beautiful beverage is nice. Thinking of it as a diagnostic tool is much more useful.

Every time you taste a cup of coffee, that beverage is telling you very specific things about what happened during the extraction. The problem is that we often don't know how to read them.

Three of the most common defects are:

Excessive bitterness
It usually appears when we over-extract. This can happen due to grinding too finely, long brewing times, or very high extraction ratios. The coffee can become heavy, with a dry, lingering finish that masks everything else.

Astringency
It's that rough feeling in your mouth, like when you bite into a green banana peel. It usually indicates uneven extraction: parts of the coffee are over-extracted while other parts haven't contributed enough.

Unbalanced acidity
Not all acidity is bad. In fact, it's one of the great virtues of specialty coffee. The problem arises when that acidity is sharp, green, or dull. This usually comes from insufficient extractions due to factors such as a very coarse grind, a ratio that's too short, or insufficient coffee-water contact time.

Learning to identify these sensations is like learning to tune an instrument: at first everything sounds more or less right, but over time you start to notice when something is out of place.

First balance, then flavor

Here comes the counterintuitive part: looking for notes before finding balance is usually a mistake.

If a cup is properly drawn, the notes appear on their own. Not because you "look for" them, but because there's nothing covering them up.
When a drink is dominated by defects, you can stretch your imagination all you want, but the result will still be a confusing cup.

That's why, when we adjust recipes in the toaster or at the bar, we don't start by talking about fruit or chocolate. We talk about:

— Is it bitter?
— Is it dry?
— Is it very acidic?

And from there we adjust grinding, ratio or time.

Improve faster

This approach has a huge advantage: it makes you progress much faster.

If you're just chasing notes, you don't know what to play when something isn't working.
If you recognize flaws, you know exactly where to start.

Too bitter → you're probably extracting too much.
Very acidic → perhaps you're understating it.
Astringent → something is not flowing as it should.

It's not magic, it's a method.

When the method is properly adjusted, the notes will appear on their own. Before searching for them, make sure the cup is balanced.