In the semi-automatic machine, water pressure and temperature must be stable and consistent, and according to our expert, the pressure shouldn't be too high. Typically, coffee is brewed at a pressure of about 10 bars, and an ideal water temperature is around 195 degrees. Generally, the more expensive the machine, the better the equipment inside that regulates these two factors. High-quality machines tend to have a mechanism called a PID, or proportional-integral-derivative, controller. The PID's function is to maintain constant water temperature with extreme accuracy, down to the degree. Two central problems plaguing inexpensive espresso machines is that they lack a PID, meaning the temperature of the brewing water can fluctuate up and down and yield inconsistent results. Inexpensive machines often advertise that they have 15 or 20 bars of pressure as a selling point. But, higher pressure is not the priority, and too much pressure can actually lead to over-extraction and bitterness in your espresso shot. Therefore, we looked for a machine with good temperature and pressure control.
A portafilter (or group handle) attaches to the grouphead of semi-automatic and piston-driven espresso machines, and carries a tamped puck of coffee grounds within its basket. It is usually made of brass for better heat retention, and is attached by a plastic or wooden handle. The portafilter forms a seal with the espresso machine's gasket, and directs high-pressure hot water through the coffee puck. After-market retailers also sell bottomless portafilters that minimize the espresso's contact with any metal. A bottomless portafilter is one tool baristas use to analyze the quality of the coffee grind and the evenness of the extraction and allows for a visual check of "channeling" or the condition in which water is able to pierce a hole in the espresso puck during the brew process leading to poor extraction. Often, baristas use knockboxes to store their spent espresso grounds after they have pulled a shot.
Picking up a bag of coffee beans from the roaster is a great way to make sure you have fresh beans. Because coffee gets damaged as it’s exposed to air, espresso connoisseurs recommend using beans within two weeks of their roast date. But you won’t want to use them the same day that they’ve been roasted — they need a few days to de-gas from the roasting process.
Our collections also include plenty of accessories to help you prepare and serve your delicious coffee. Serve coffee in style on one of our Williams Sonoma coffee tables. Browse a selection of consoles, side tables and rectangular tables that complement almost any space. If you opt for a capsule machine or a stovetop espresso maker, you may want to choose some accessories to enhance your drinks. Coffee accessories such as mills and scales can help improve flavor. If your maker of choice doesn’t include a frother, our collections offer a variety of options, from small handheld devices to slightly larger models that can froth a few cups of coffee at once.

It can take a little while to get to know the ins and outs of a new coffee maker. In CR’s labs, each drip coffee maker we test brews roughly 65 cups by the time our engineers are through with it. And brewing is just one of many aspects we look at. We test for handling and convenience, too, so you can choose a model that helps you sail through morning madness. 
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