Extraction science, brewing standards and hardware analysis for people who weigh the dose to a tenth of a gram — labelled bench-tested or research synthesis, never blurred.
I weigh the dose, log the shot, and publish the numbers — or say plainly when the gear isn't mine to measure. Everything here carries one of two labels so you always know which you're reading. How we test →
Paper keeps all but a trace of the cholesterol-raising cafestol out of the cup. Metal is not one thing: a reusable nylon filter measured against paper let through eight times as much, a French press 35 times. What that means in cholesterol, and what is and is not known about taste.
The SCA has had a certification standard for home grinders since 2022 and has never listed a grinder under it. This summer a 'Home Filter Grinders' tab appeared on its certification page; it is now hidden, and the only thing behind it is a coffee maker. The one lab that approves home grinders is the lab the SCA sends its own tests to — and its version of the test asks for more.
Two of the most-linked grind charts on the internet disagree by 300 microns on the same brewing method, and one of them sources its numbers to reader feedback. Meanwhile the three documents that were obliged to define a coffee grind — two standards and a brewer certification test — all refuse to give a single number, and the one lab that published measured medians for drip put them where the charts say French press.
Every page answering this question gives you the same paragraph about surface area and over-extraction, and none of them gives you a size. The experiments that did measure it found something more useful and less flattering: in drip, a grind change large enough to move strength by a fifth was not reliably detectable, while the shape of the brew basket was. And bitterness, in the study that separated the two, tracked concentration rather than extraction.
The physics and chemistry of the shot: pressure and flow profiling, TDS and extraction yield, puck preparation and channelling.
Open pillar → 5 piecesPour-over, immersion and cold brew — grind, temperature, agitation and the paper itself.
Open pillar → 4 piecesSingle-dose grinding, burr geometry, particle distribution, retention and alignment. Flat versus conical, and what actually reaches the cup.
Open pillar → 2 piecesTampers, WDT tools, baskets, scales, cleaning chemistry and the small kit that quietly decides shot quality.
Open pillar → 1 pieceBoiler architecture, thermal stability, pump and group head design — from entry-level single boilers to prosumer dual boilers.
Open pillar → 1 pieceMineral architecture, SCA targets, buffer and hardness recipes, and why the same beans taste different in another city.
Open pillar →
Most gear sites tell you what they think. This one tells you where the number came from. Every piece carries one of two labels before you read a word of it: research synthesis, meaning the hardware is not mine and every figure is attributed to whoever did measure it — or bench-tested, meaning I bought it, measured it, and published the rig alongside the result. Nothing sits in between, and nothing borrows someone else's numbers without saying whose they are.