Grind setting vs. the effect of tamp pressure

[Re Re]

If, keeping the Golden Rule in play, does a coarser grind with a greater tamp pressure or a finer grind with less tamp pressure produce a consistently better shot?

[peacecup]

Check out the "To tamp or not to tamp" thread on the lever forum.

[timo888]

I cannot answer the question, which approach produces a consistently better shot. However, I can answer the question, which approach produces a consistently good shot: the approach that is consistent.

If it's a human, and not a machine, doing the tamping, consistency is more easily achieved with no tamp whatsoever, or a very light tamp, than with a heavier tamp of an arbitrary force.

Regards
Timo

[HB]

If, keeping the Golden Rule in play, does a coarser grind with a greater tamp pressure or a finer grind with less tamp pressure produce a consistently better shot?

Of the factors behind an exceptional espresso, the tamp is way, way down on my list of difficult skills to master. Sometimes I will "cheat" by tamping harder/softer to compensate for a grind setting that's slightly off, but only if I'm rushed. As Tim said, consistency is the key, whether it's 5, 10, or 30 pounds of pressure.

We once did an informal test to judge how consistent your average home barista was. With Kevin's permission, I've excerpted our Tamping pressure challenge results below.

Each participant was given 1 "calibration" tamp on the countertop with an Espro 30lb tamper and standard dial-type bathroom scale. Each participant waited a few minutes and the proceeded to make 6 measured tamps using a standard 58mm Reg Barber style tamper. Each CG used the same tamper and scale for all tamps.

Here are the results of the first 6 measured tamps:

Table:

A  B  C  D  E  F  G
--------------------
19 32 35 35 35 32 30
25 27 37 31 27 27 28
29 25 35 27 24 26 40
28 25 35 25 26 29 35
32 23 35 25 25 30 36
30 24 35 36 25 30 37

After the initial tamps, we pondered the meaning of all things coffee over a few shots and cappas made with some Black Cat and a "mystery blend" provided by CCC. We then proceeded to make our "for the record" tamps. Each of the participants were asked to step up to the scale and again make 3 tamps for the record. Approx. 30 seconds elapsed after each tamp:

Table:

A  B  C  D  E  F  G
--------------------
25 31 42 38 36 32 30
22 27 40 40 30 31 29
26 29 36 46 30 34 32

None of the participants are professional baristas.....Therefore we surmised that if a reasonable degree of consistency can be achieved by us CG's, then a click type tamper can be an invaluable training aid to any barista, if not a full use device.

As always, there are exceptions to the "consistency is all that matters" recommendation above. Tim pointed out and several people including me confirmed a light tamp/coarser grind does benefit multiple pull lever extractions (link).

[timo888]

The best thing to do is to set up your own taste comparisons on the kinds of questions that can be easily answered without any special equipment.

For starters, set the grind fineness, so that with ~14g in the double basket or ~7g in the single basket, and with no tamp whatsoever but simply a settling of the basket contents using some gentle raps on the countertop or some chop-chop-chops with the edge of the spoon handle, the resulting pour is steady and viscous and not too slow or too fast.

Then make the grind coarser and tamp with your ~30 pounds.

As always, use freshly roasted coffee, i.e. a week from the roast date, give or take a few days in either direction.

Regards
Timo