Why your shots run too fast, and why grinding finer stops helping

A shot that blows through in twelve seconds has an obvious first answer: grind finer. That works right up until it does not — and past that point, grinding finer makes everything worse.

The reason is that there are two entirely different causes of a fast shot, and only one of them is about grind size.

Cause one: the grind really is too coarse

Symptoms are undramatic and uniform. The shot runs fast, the stream is even, the puck comes out wet but intact, and the coffee tastes sour and thin — under-extracted across the board.

Grind finer in small steps. This is the ordinary case, and it is what grind adjustment exists for.

Cause two: channelling

Symptoms are dramatic and uneven. The stream sprays or splits, one spout runs before the other, the shot starts pale and then goes blonde early, and the puck has a visible hole or crater. The taste is the giveaway: sour and bitter at the same time, because part of the puck over-extracted while the rest barely wetted.

Grinding finer here is actively counterproductive. Finer grounds raise resistance everywhere except the existing crack, so more of the water goes through the crack. You end up at a grind setting that would choke a well-distributed puck while still getting a fast, hollow shot.

How to tell in one shot

Look at the puck.

• Even, smooth, holds together, uniformly wet: grind problem.
• Hole, crater, pitted surface, or a wet patch on one side: channelling.

And look at the stream in the first five seconds. Espresso should start as a single dark drip that turns into one or two steady streams. Anything that sprays sideways or splits into three is channelling, every time.

Fixing channelling, cheapest first

Free:

• Stop tapping the portafilter on the counter. Tapping settles fines to the bottom and can crack the bed. It is the most common cause of channelling in home setups.
• Level before you tamp. A bed that is higher on one side compresses unevenly no matter how hard you press.
• Tamp level, not hard. Above about 15 kg the extra force changes nothing measurable. Level matters; heavy does not.
• Do not knock the portafilter after tamping. That is how a sealed puck gets cracked at the edge.

Cheap:

• A distribution tool (WDT). Stirring the dry grounds with fine needles breaks up the clumps that come out of every grinder. It is the single most effective fix for channelling in home espresso, and it costs very little.
• A paper filter under the puck. It evens out flow at the base and keeps the screen cleaner.
• A calibrated tamper, if your tamping is inconsistent between shots.

Only after all of the above:

• A different basket. Precision baskets have more consistent hole patterns, and they help — but they help a well-distributed puck, and they will not rescue a badly distributed one.

The stale-coffee case

One more possibility worth naming: very fresh coffee, within about three days of roast, degasses hard under pressure and can crack its own puck. If shots suddenly turned erratic when you opened a new bag, rest the bag a few more days before rebuilding your whole routine around it.

Where the money actually goes

Almost everything on that list is free or costs less than a bag of coffee. The expensive part of an espresso setup is the machine and the grinder — and that is the part where the store you buy from matters. Across the products several of our tracked stores sell identically, we currently see a typical spread of $68 between the cheapest and dearest. See what that looks like.