Portafilter

Clamps a basket of ground coffee into the group head and holds it there against brew pressure — and in one of its forms, shows the barista exactly what the water did on the way through.

A handle, a body, a seat for the basket, and lugs that engage the group and pull the whole assembly up against a rubber gasket. Beyond that, the portafilter contributes to the cup in exactly two places. The first is thermal: the body is a solid mass of metal sitting at room temperature between shots, and brew water gives up heat to it before it reaches the coffee — which is why a portafilter parked on the mat produces a first shot noticeably different from the one that follows it. The second is the underside, and it is the one worth understanding before buying anything. A spouted portafilter has a chamber below the basket where every jet of coffee leaving the filter is collected, mixed and split between the spouts; the flows recombine, so whatever variation existed across the bed is averaged out before anyone can see it. A bottomless portafilter has that chamber machined away and the basket's underside exposed to the air. Nothing recombines. Each region of the puck now reports for itself, and anywhere water found an easier path shows up as a jet, a spray or a pale streak while the shot is still running. That is not a preference and it is not an upgrade — it is a measuring instrument, and what it measures is channelling, which is otherwise invisible until it appears in the taste of a drink nobody can explain.

• Own one portafilter per group plus at least one more in rotation, and treat the spare as a temperature decision rather than a convenience. The metal has to be hot before the water goes through it, and the only way a barista gets a hot one on every drink is to have one warming in the group while the other is being dosed. A bar that owns exactly as many portafilters as it has groups has decided, without noticing, that every shot will start from a cooling body.
• Buy the bottomless deliberately, as a training and calibration instrument, and say that out loud when you buy it. It is the cheapest diagnostic on the bar: it converts "the shots taste inconsistent" — an argument — into a visible fault a new barista can watch themselves cause and correct inside one session. It is also the wrong thing to run a milk rush on, and buying it as a service default is how a team ends up wiping the counter between drinks.
• The portafilter, the basket and the tamper are one decision, not three. The basket has to seat properly in the body and the tamper face has to reach the basket wall, and a mismatch anywhere along that chain leaves an unsupported ring of coffee at the edge for water to escape through. Order them together, and check the fit physically rather than from a compatibility chart.
• Judge the handle by the hundreds of times a shift it is gripped, not by how it photographs. Length changes the leverage needed to lock in, material decides whether it is comfortable to hold after an hour in a hot group, and both land on the same wrist that is already absorbing every tamp. This is the field where an operator's own hands are better evidence than any specification.
• Do not buy a bottomless to fix consistency. It reports the fault; it does not correct it. The correction is grind, distribution and tamp, and it is entirely possible to spend the money, mount the instrument, watch the spray every morning and change nothing that the spray is telling you — which is worse than not owning one, because now the fault has been seen and tolerated.
• If the menu sells a single shot, calibrate it as its own drink or stop selling it. A single basket run on the double's grind gives a fast, thin, sour shot, and it will be served to the customer who ordered the smallest thing on the menu and formed their entire opinion from it.
• Count spares against replacement lead time, not against breakage rate. A cracked body or a stripped lug takes a whole group out of service, and a group out of service during the week it takes a part to arrive costs more than every spare you would ever buy.
• Specify a body you can get inside. The chamber under a spouted basket collects coffee oil continuously, and spouts that do not come apart produce a portafilter that is cleaned on the outside and never underneath. The taint arrives weeks later, tastes like stale oil in every drink, survives a change of coffee, and is usually blamed on the roaster.