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 →
In a healthy brewer, most of the heat you miss is lost after the coffee leaves the basket, and the two problems have different fixes. The SCA caps a certified carafe at 85 °C on purpose, UC Davis could not taste 87 °C from 93 °C once extraction was matched, and a thermometer in the basket tells you which problem you have.
Every guide treats channeling as a fault you either have or you don't, caused by grind, distribution or tamp. The published physics says something stranger: uneven flow between pathways is always present, it feeds on itself, and for most of a shot it hides behind an average that looks fine. Here is the causal chain, from the first 6.7 seconds of wetting to what the spent puck looks like under an x-ray.
The espresso world sells three puck prep tools and has run a controlled trial on one of them — which lost. The peer-reviewed literature says the tamp exists to level the bed, not to compress it, and the arithmetic says why: the pump presses the puck about twelve to twenty-four times harder than your hand can. Here is what has actually been measured, including the study that made a puck deliberately uneven and got a more stable shot.
Every page on this search tells you a wet puck means your grind or your tamp is wrong. A measurement nobody cites says otherwise: on a commercial machine at a verified 9 bar, a 20 g puck holds 20.85 grams of water — and that figure did not move when the burrs went from new to worn out. Here is what is actually in the basket, what removes it, and what the removal costs.
The physics and chemistry of the shot: pressure and flow profiling, TDS and extraction yield, puck preparation and channelling.
Open pillar → 4 piecesSingle-dose grinding, burr geometry, particle distribution, retention and alignment. Flat versus conical, and what actually reaches the cup.
Open pillar → 4 piecesPour-over, immersion and cold brew — grind, temperature, agitation and the paper itself.
Open pillar → 1 pieceMineral architecture, SCA targets, buffer and hardness recipes, and why the same beans taste different in another city.
Open pillar → 1 pieceTampers, WDT tools, baskets, scales, cleaning chemistry and the small kit that quietly decides shot quality.
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.