Pressurized vs non-pressurized baskets: what's in the box, and which to use

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Every entry machine ships with a small steel basket or two, and which kind it is decides whether you are making espresso or something that looks like it. Here is the difference, in the makers’ own words.

Two kinds of basket

A single-wall (non-pressurized) basket has a flat bottom full of fine holes. The only resistance the water meets is the coffee itself, so the grind, the dose and the tamp have to be right, and when they are, the result is espresso.

A dual-wall (pressurized) basket has a second wall under the first with a single tiny hole. The hole creates the resistance, whatever the coffee is doing. Breville’s manual: dual-wall baskets “regulate the pressure and help to optimise the extraction regardless of the grind, dose and tamp pressure or freshness”, and are for “pre-ground coffee and older beans that are past the 30 day roast date”. Single-wall is for “fresh whole coffee beans roasted less than 30 days” and “allows you to experiment with grind, dose and tamp”.

Why both exist

A pressurized basket makes a forgiving drink from supermarket grind, which is how a machine works out of the box with no grinder. It also makes a thick, fizzy foam the makers call crema, which is mostly the hole whipping air into the shot. That drink is fine. It is not what the rest of this site is about, and it does not improve with a better grinder, because the basket is doing the work.

Which machines ship which

Breville (Bambino, Bambino Plus, Barista Express, Impress, Pro): both kinds, one- and two-cup, 54 mm.
De’Longhi Dedica Arte and Stilosa: pressurized only (De’Longhi’s “dual wall” and “crema” filters). A single-wall basket is a third-party purchase, 51 mm by third-party measure; De’Longhi doesn’t publish the size.
Gaggia Classic Evo Pro: 58 mm portafilter with baskets for 7–18 g; the maker’s page doesn’t say which type, and the listings describe one pressurized and one not.
Rancilio Silvia: single-wall 8 and 16 g baskets.
Flair Classic and Picopresso: non-pressurized, 40 mm and 52 mm. Nanopresso: pressurized.

Thermojet, PID, manual steam, 54 mm

Breville Bambino

Breville BES450

The small machine that changed the entry level: hot in three seconds, PID temperature control, low-pressure pre-infusion then 9 bar, single-wall and dual-wall 54 mm baskets in the box, and a manual steam wand that makes real microfoam.

Heater: ThermoJet, ready in 3 s
Temperature: PID
Pressure: 15 bar pump; low-pressure pre-infusion, 9 bar extraction
Baskets: 54 mm; 1 and 2 cup, single wall and dual wall
Steam: Manual wand
Tank: 47 fl oz
Size: 11.9 × 6.1 × 13.5 in; 10.42 lb; 1,560 W
Warranty: 1 year

Suits: A small kitchen and a separate grinder. The machine most of this site assumes.

Weigh: Light, plastic-bodied, a tiny drip tray and no pressure gauge. No grinder; that is the point, and the budget.

View on Amazon

Which to use

Start on the dual-wall basket the first morning, with whatever coffee you have, to learn the machine without fighting it. Then, with fresh beans and a real grinder, move to the single-wall basket and dial in. The first few shots will be worse than the pressurized ones. The tenth will be better than anything the pressurized basket can do.

Sizes, and why they matter

The basket diameter decides every tamper, funnel, portafilter and upgrade basket you buy for years:

54 mm: all five Breville machines (maker-stated). Tampers are sold as 53.3 mm to fit.
58 mm: Gaggia Classic Evo Pro (maker-stated); the café standard, so accessories are everywhere.
57 mm: Lelit’s small machines.
51 mm: De’Longhi, by third-party accessory makers; De’Longhi doesn’t say.
52 mm Picopresso, 40 mm Flair Classic (maker-stated).

The tools page is built around the 54 mm size, with the other sizes noted on each card.

Bottomless portafilter for Breville machines

Normcore 54 mm bottomless portafilter

Normcore Bottomless 54 mm, 18 g basket

A portafilter with no spouts, so you watch the shot come straight out of the basket: channeling, spraying and uneven extraction are visible instead of guessed. Comes with an 18 g basket for Breville's 54 mm group.

Fits: Breville 54 mm (Bambino Plus, Barista Express, Pro, Touch) (listing)
Basket: 18 g included

Suits: The Bambino, Barista Express or Pro owner who wants to see what their puck prep is doing.

Weigh: A bad puck sprays the counter and you, which is the point. Fits Breville's 54 mm machines; not for De'Longhi or 58 mm. Specs are the listing's; Normcore's page for this item wasn't reachable.