We stopped "tapping" in 2006.

Instead, we "thump."

Thump = thumping the portafilter on the counter between tamps, instead of tapping with the tamper.

Our reasoning: if, theoretically, you wanted to hit the portafilter with the tamper, and with as little force as possible, and your goal was to BREAK the tamped puck or break the seal with the side of the basket, you'd strike it... pretty much where baristas do now. A lateral and slightly-downward blow with the tamper-handle on the upper-edge of the portafilter.

"Thumping" the portafilter moves the loose grounds to the middle, but the puck is cradled by the basket, with the force-vectors of both moving together. With a "tap," your force-vectors are working against each other.

Ninth Street Espresso in NYC adopted this practice last year.

A no-tap works too.

Just remember to dose and distribute properly, please!

I must say, that you guys got me all confused now.

You recommend others (and probably do it yourselves) to get a good if not great tamper, and people spend 30-200$ on that. I've never seen anyone here advices against buying a good tamper, and now you say things like:

"tamp is at the bottom of my list of critical success factors."

"Despite all of the ritualistic observances attendant upon it, tamping is unnecessary. You can pull an excellent shot with no tamp whatsoever"

and there are more...

I've got to ask: If its that not important, why even bother with the tamper?

Good question, and it is confusing isn't it.

There are as many techniques as there are baristas, if a no tamp shot works good for you, than go for it. When I say the tamp is at the bottom of the priority list, I am not saying that you do not need to tamp, or that a sloppy tamp or ill fitted tamper will not cause problems. However in the grand scheme of the espresso ritual, the tamp is the easiest to learn and least critical in my opinion. Far more important is the quality of grind, consistency of dose and evenness of the distribution. Think of it as the icing on the cake. Even the best looking icing will not improve a bad cake, but improperly made icing will diminish the quality of the final product. In my opinion, you still need a properly fitted tamper and a good tamp but if your grind/dose/distribution is off no amount of tamping will help.

Based on my experience and posts by others, I have come to the conclusion that the tamp serves two useful purposes:
1) the compacted surface of a tamped puck provides more resistance against channeling, especially when the first blast of pressurized hot water hit the coffee grinds;
2) the tamp locks in the distribution.

In support of the first point, I'll quote from Mark Prince's Tamping Science article on CoffeeGeek:

First, ground coffee is a wide range of particle sizes within it's scope of "espresso grind", and those grounds form a kind of interlocking puzzle when compressed. The more pressure exerted on the interlocking pieces, and the tighter the overall fit is.
...
Simply put, when you tamp by hand, you're tightening up the pieces of the puzzle at the top of the formed puck quite a bit; less so by the time you get midway down the puck, and very little, if any tightening at all by the time you get to the bottom few millimeters.

After tamping, I typically brush stray coffee grinds off the lip of the basket and invert it briefly. After a 30# tamp, the puck never falls out (well, almost never ). This is good evidence in support of the second point.

kramerica wrote:"tamp is at the bottom of my list of critical success factors."
"Despite all of the ritualistic observances attendant upon it, tamping is unnecessary. You can pull an excellent shot with no tamp whatsoever"
and there are more...
I've got to ask: If its that not important, why even bother with the tamper?

This may be an issue of semantics. Tamping may be less important than grind, dose, and distribution, but it's still a critical factor in puck preparation.

Back on track: what about tapping?

Nick wrote:Our reasoning: if, theoretically, you wanted to hit the portafilter with the tamper, and with as little force as possible, and your goal was to BREAK the tamped puck or break the seal with the side of the basket, you'd strike it... pretty much where baristas do now. A lateral and slightly-downward blow with the tamper-handle on the upper-edge of the portafilter.

I think Nick is absolutely correct with this observation. A good way to dislodge a tamped puck from the basket is to invert it and rap it on the side. The side tap is very effective in breaking the seal between the puck and the basket. It increases the chances of side channeling during the pour, and may introduce microfractures inside the puck. Quite simply: tapping the side of the basket should be eliminated from puck preparation.

A downward tap (or "thump") before tamping is a completely different animal. The downward thump is an extremely effective way to updose. In the following, I first dosed a LM/Synesso 14g ridgeless double basket and leveled to the rim without any tapping. Then I redosed the same basket, giving a couple of sharp downward raps before leveling. The dose difference was almost 6 grams (!).


The downward thump clearly causes redistribution of the coffee grinds, filling in air pockets as well as settling the grinds evenly throughout the basket. This is a valuable technique in the barista's arsenal, if used prior to the tamp. However, since the tamp serves to lock in the distribution, you should not do anything to disturb the puck after tamping - including thumping. Just lock in and pull your shot.

I find this subject somewhat interesting whenever it seems to come up. Many individuals, including myself, will state that skills such as tamping and incorporating a tap are way down on the list of important steps to a properly extracted shot of espresso. However, just as a preceding post states, that does not necessarily mean that tapping is unnecessary or without consequence (although many people will argue that it is not needed). It's just that it is ludicrous to obsess about "if" or "how" to tap without first being proficient in the preceding variables such as coffee, grind, dose, redistribution, etc. But, a preceding post made a good mention of this already, so I digress...

Speaking of variables, I think that some things get lost in the discussion of tapping when the argument is simply whether or not to do it. IMUO, I think that there is great importance to not applying too much pressure with the tamp that is preceding the tap. There is the frequent mention of a preceding "light" tamp, but that has different meanings to different people.

If the preceding tamp is of significant pressure, then the likelihood of the puck fracturing and/or losing significant side seal is more likely when it undergoes a tap. I believe the likelihood of such problems occurring is more so with the side tap than with a counter tap or "thump" as Nick describes above. Give some thought to what he mentioned about vectors. Remember, the coffee cake is not uniformly compressed / interlocked from top to bottom, so certain parts of the puck will be more prone to shifting and causing trouble as the differences of compression between the top and bottom of the puck increases (a heavy initial tamp increases the differences of compression throughout the puck). It is difficult to correct such fractures or losses of side seal with a repeat tamp when the coffee has already been significantly compressed.

Then there is the use of a flat versus convex tamper. There is usually little mention of what type of tamper geometry the individual is using when discussing the success or failure of incorporating a tap. After taking Thought Experiment Theory 451 (yes, it is a 400 level course), one would expect a convex tamper to more easily correct side seal issues on the second tamp than a flat tamper.

But, when getting into all of this stuff which further generates more questions and debate, it is much easier to tell people "Eliminate the tap".

Coming in a bit lately
(I wanted to see the most of answers by the more experienced ones)
I have a question: what was originally the purpose of the tap?

As for my own to-tap-or-not-to-tap, I have a little story to share.

When I first learned anything about espresso preparation, I learned to 'tap with minimum force to dislodge coffee from the inner wall of the basket' (guess who wrote it... or maybe you should remember). So, literally, I started doing it.
Then, after having read a bit more, I started wondering if I do achieve the aim, that is the 'dislodging...', because all the loose coffee grounds above the puck were still there after my 'minimum force tap'. So I started to tap with more force... only to find that there is absolutely no reasonable force to make the grounds go their way down onto the surface of the tamped coffee (the unreasonable force just spoils the whole puck). So, I decided to give up tapping. Yet I didn't give it up for long, you see... my shots are more likely to channel when I don't tap:

1. dose->wdt->light tamp->tap->30pounds tamp->go: better then
2. dose->wdt->light tamp->30pounds tamp->go,

but I did not remove the tamper from the basket after light tamp in the 2.

So, I thought for a moment and concluded that maybe Schomer wasn't thinking of the loose grounds above the puck on the basket walls (or not only about it)? But anyway, after watching some videos (one with fancy four taps by one HB-elder and one with some forty taps by an all-laughing woman) I decided to have a try of tapping twice... and well, it works: no loose grounds above the puck, no side channeling.

OK, so that's the story; don't forget my initial question
And disclaimer: I don't mean the no-tap way is wrong. Maybe I should for instance remove the tamper from the basket after the light tamp before the 30pounds tamp to have better results with no-tap?

Now for the no-tamp zone: I have no experience with no tamp, but what strikes me is this: if I would like to try the no tamp, then I would have to downdose very much to avoid compressing the loose puck with the dispersion screens.

And for the importance of the tamp: with grind off, floating dose and poor distribution truly there is nothing to tamp (unless you want to have a go pressing down a bathroom scale ), but once you have these three down in your basket, then when you screw up the tamp, it's all gone (OK: maybe only for me learning to tamp was not the easiest part).



EDIT: I typed it in before reading Matthew's post. Well, I'm capable to do a lot of typing!

I admit to being a tapper most of the time. During grinding I rapidly thwak the doser lever while rotating the portafilter and tapping the bottom of the portafilter on the grinder portafilter fork. After sweeping the coffee level with the basket a leveling tamp with basically no force, just the weight of the tamper is followed by a very light tap on the rim with the tamper handle to knock down most the grinds clinging to the side. Then a traditional heavy (~#30) tamp.

Maybe a bad habit. But when I catch myself to not tap there has been no direct correlation with the quality of the shots pulled on the MicroCasa a Leva or Ponte Vecchio Lusso.

If I decide to go with a much finer grind and the very light, my pseudo "no tamp" the process of preparing the portafilter ends with the leveling "tamp".

With either tap, no tap, tamp , no tamp if the degree of grind, dose, distribution are on the shots are usually acceptable. So I guess an answer to the question is: No good reason to tap, just a habit. Should stop. Excessive motion serving no real purpose.

kramerica wrote:I've got to ask: If its that not important, why even bother with the tamper?

You may find it interesting to read the Tamper Road Show

A close fitting tamper minimizes the mess.
A tamper piston of the 'proper height' maximizes off level indication. Proper height varies by machine and dose level.
A curved base may allow a tad more updosing in some instances.

Using the 4M's and assigning values to importance
Miscela : 8 : if the coffee is crap, nothing else will help
Macinazione : 4 : with good coffee, you're half way there, now it needs to be properly ground
Macchina : 2 : it's just hot water
Mano : 1 : if all of the above are spot on, it's a doddle.
Tamper : 0.1 : or less than 1%

Paramount is that it fits your hand and is comfortable to use.

you know what happened today?
I wanted to have a try with the rap-against-the-counter and in spite of all the anticipation I forgot to do wdt.
I dosed, did rap the pf against tamping stand three times and in that moment I realised I forgot to wdt. I didn't want to be spritzed with coffee (I was in a suit for I just returned from a job interview) but I said 'oh well' and just proceeded with a light tamp and a tamp.
It was a good shot! around 24s, tasty, even bidding...
a lesson to learn: simplicity?

RapidCoffee wrote:Based on my experience and posts by others, I have come to the conclusion that the tamp serves two useful purposes:
1) the compacted surface of a tamped puck provides more resistance against channeling, especially when the first blast of pressurized hot water hit the coffee grinds;
2) the tamp locks in the distribution.

In support of the first point, I'll quote from Mark Prince's Tamping Science article on CoffeeGeek:

I see merit in the "first blast" argument, but the channeling explanation seems wrong.

The swelling of the puck tightly against the sides of the basket and the interpenetration of grains that occurs as a result of hydrostatic pressure is orders of magnitude greater than any interlocking that occurs mechanically as a result of tamping. You cannot quarry stone with a tamper, but you can with a dried peg and some water. It is this swelling under hydrostatic pressure throughout the puck, not merely a carapace of interlocking grains, that prevents channeling. If this weren't the case, you'd see channeling in untamped shots; you don't-not with a proper preinfusion.

Tamping, while unnecessary, does have some benefits, IMO, especially if it is a light tamp. With a light tamp you get all the benefits of a tamp (headroom & protection against the force of the "first blast") and none of the bad effects of a heavy tamp. A heavy tamp can lead to side-channeling, perhaps not directly, but indirectly; a heavy tamp is often used in conjunction with overdosing, and an overdosed basket is one more susceptible to channeling, not less susceptible, especially if the machine is one where pressure is allowed to increase inordinately in order to overcome great resistance from the cake.

Regards
Timo