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My point was you want it as compressed as possible - anything else is not repeatable by a human making a mockery of your careful attempts to get pressure, extraction time, heat and volume consistent.
So there is no scale to tamping - it’s either tamped or it ain’t. ‘light tamp’ is a nonsense - unless you are not trying to make espresso and just pissing about. Which is what the guy was doing, it turns out.
The opposite of a heavy tamp.
The pressure at which you tamp will determine how compressed the puck is.