How Filter3 works

Filter3 is the third version of Scott Rao’s method for making filter coffee on an espresso machine. A paper filter sits in the bottom of the basket, with a deep chamber above it for a loose bed of very coarse coffee. The Filter3 profile starts with a pre-wet of about three times the dose (roughly 66 g of water for 22 g of coffee) and a 30 second bloom, then runs a series of slow-flow stages in which the water temperature steps down as the brew goes on, which limits over-extraction towards the end. The whole brew takes about four minutes, and once the basket is locked in you only press one button.

Rao and Decent Espresso give a target of 22 to 23% extraction at 1.4 to 1.5% TDS. Unlike the earlier Filter 2.0 method, the coffee is ready to drink straight away without adding bypass water, although you can add 30 to 40 g of water if you prefer a lighter cup.

Check your machine before buying

The basket drops into any standard 58 mm portafilter, but fitting is not the same as working. Filter3 depends on the machine delivering water very slowly, around 2 ml/s, and holding that flow for several minutes. Decent Espresso machines have a Filter3 profile in the app. Owners of other flow-profiling machines have built their own versions of the profile, but you will need to set up and tune it yourself. A pump machine without flow control will not brew good Filter3 coffee.

Dialling it in

Expect to spend some time on the first brews. Start by running the profile without the portafilter and weighing what comes out: the target is about 360 ml of water in total, and if your machine delivers more, lower the flow rate slightly in the profile steps and run it again until you are within about 30 ml. A Bluetooth scale such as the BOOKOO Themis Ultra, which connects directly to Decent machines, makes this calibration quick.

To brew, centre a paper in the bottom of the basket and wet it, add 22 g of very coarsely ground coffee, shake the basket to level the bed and lock the portafilter in gently. Grind size is the main adjustment. Around 100 seconds in, Rao checks the slurry: it should reach about halfway up the basket. At 60% or higher, grind coarser next time; below 40%, grind finer. If water escapes through the holes near the top of the basket, the grind is much too fine.

Paper filters

The Filter3 papers are cut from the same paper as the NextLevel Pulsar filters, chosen for low flow resistance and a high capacity for holding fines. Most 58 mm espresso puck papers are not porous enough for this style of brewing and will not work well, so stick with the matching Filter3 papers. 100 are included with the basket, and refill packs are sold separately.

A note on finish

Scott Rao points out that some baskets leave production with small cosmetic marks or scratches. These do not affect how the basket brews.

Specifications

What’s in the box

• Scott Rao Filter3 basket