the nine requirements of a certified Italian espresso, with their tolerances
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
The figures come from the Istituto Nazionale Espresso Italiano booklet. Each band shows the allowed departure as a fraction of the figure itself.
Percolation time is allowed to run from twenty to thirty seconds — one fifth of the figure itself, and the widest band of the six. The water leaving the unit carries a similar-looking «two» after its plus-minus, but against eighty-eight degrees that is one forty-fourth: a band almost nine times narrower. The standard therefore watches most closely not the number a barista reads off the timer, but the one that cannot be seen at all without a thermometer.
The bands are reduced to a fraction of the standard’s own figure, since seconds and milligrams cannot otherwise be compared. For the two temperatures it is worth remembering that degrees Celsius are counted from an arbitrary zero, so what is shown there is a tolerance of the setting rather than a fraction of heat.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 6 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
