ARO Core Aluminum Espresso Extraction Chiller, One or Two.

A frozen slug of solid aluminum that the shot runs over on its way into the cup. Chilling the first seconds of an extraction keeps volatile aromatics in the liquid instead of the air, and the difference in the cup is a sweeter, rounder shot. Most chillers are stainless balls, sometimes hollow ones filled with gel. ARO machined this one from aluminum on purpose. Shipped direct from ARO Espresso.

Why aluminum

Aluminum conducts heat roughly twelve times faster than stainless, so it pulls temperature out of the first part of the shot quickly. It also has a lower heat capacity, so it equalizes with the espresso and lets the back half of the shot warm the cup again. In practice you leave it in for the whole double at 1:2 and the espresso lands at drinking temperature. Experiment with exposure time if you want to tune it.

Shape

Pointed at both ends with about ten percent more surface area than a sphere, so the flow attaches and sheets from top to bottom. A separate support plate sits on almost any cup and holds the chiller centered; the plate's outer ring gives you something to hold without warming the metal.

Use

Chillers live in the stand in the freezer; give them at least an hour. Plate on the cup, chiller in the plate, cup under the portafilter, pull the shot as normal. The stand doubles as an insulator on the way to the machine.

One or two

One chiller with a one-slot stand, or two chillers with a two-slot stand for back-to-back shots. Both include a single support plate.

Ships direct from ARO Espresso.