How important is tamping coffee for an espresso machine

18

I observe that coffee servers (I refuse to use the term barista) will apply pressure to the coffee grounds using a variety of methods and pressure. This seems to vary wildly and I'd like to know how important is this? Is there some general rule of thumb when it comes to recommended pressure?

My thoughts were that the fineness mattered the most for espresso machines and that reasonable enough pressure when tamping is enough but what do expert's use and believe.

EdChum

Posted 2015-01-27T20:34:58.077

Reputation: 1 345

Answers

14

Let's start off with what the function of the tamp is.

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Function

The tamp is cylindrical in shape and is ideally just snug enough to fit into the portafilter smoothly. What the tamp does, is prime the coffee bed to be met with water. What we know about the water is that in general, in commercial machines, water is applied with 9 bars of pressure. Physics tells us that pressured water flow will take the path of least resistance. By this logic, the tamp functions by making the coffee bed smooth, even, and robust enough to be hit with 9 bars of pressure and extract evenly.

Barista Health

Note: In no way am I a qualified physician. This is not to be considered medical advice.

If the surface one tamps on is on the proper level, the barista should be able to tamp with their elbo at a 90 degree(ish) angle, and their wrists in a semi-straight path to prevent damage. The barista can then use their body weight, and not muscle, to perform the tamp. By leaning into the tamp with the correct path, one can achieve about 30lbs of pressure.

Experiments with varying pressure

Personally I have experimented with varying pressured tamps and have found that applying a greater pressure than 30 lbs produced little effect, at most, a longer extraction. There are other variables that should be adjusted instead, such as the grind size, to achieve such an effect.

John Snow

Posted 2015-01-27T20:34:58.077

Reputation: 1 299

17

Tamping is one of three key controls you have over the espresso brewing process; The others are dose (the amount of coffee used) and grind coarseness. Together, they allow the coffee machine operator to produce a puck of the correct density and consistency through which the pressurized water can be pushed through.

While techniques vary, the "rule of thumb" is to apply roughly thirty pounds of force evenly across the puck; however, the key is consistency. Keep your variables the consistent and you'll be able to dial in the best end-product.

I've been able to pull great shots using anything from just the weight of the tamper itself to my full weight pushed onto a puck, keeping all of the other factors where they needed to be to create the correct puck density.

See this video below for more detail: What is the Right Way to Tamp?

Kyle Macey

Posted 2015-01-27T20:34:58.077

Reputation: 1 219

Kinda related then is why do some people when freshly grinding the coffee feverishly swing the lever that dispenses the ground coffee into the espresso holder, they do this repeated lever action with the grinder that puzzles me, perhaps I should post that as a question – EdChum – 2015-01-27T20:49:45.450