I still hear people talking a lot of talk about how a harder or lighter tamp will affect the flow rate of a shot. I'd have to disagree from experience. Holding the dose constant I've tamped from 10 to 80 lbs of pressure and still ended up with consistent flow rates. example 18g dose 10lb tamp 27seconds to 2oz. then holding 18g constant tamped up to 80 lbs and still getting to 2oz in 27 seconds +/- 1 second.

I really believe that it's primarily the amount of coffee and the particle size of the grounds that ultimately have the most influence on flow rates. I've even skipped the tamp altogether expecting a gusher, but surprise... still poured near 25 or so seconds. Didn't taste that good... much different flavour profile; puck looked like it was tamped though... The pressurized water is tamping the puck harder than most of us will ever be able to anyhow.

I think that different tamping pressures could possibly change some of the dynamics of the extraction within the puck... ideas anyone? I think I may have noticed that blonding & thinning strands occurred sooner when tamping with excessive force (60 lbs +).

would like to get some feedback and see if anyone has other evidence to the contrary, or just other insights...

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and that is why I love this forum. We discuss things.
as Mr. Jarrow stated, the amount of pressure produced by the espresso machine is going trump any amount of pressure you might be tamping with. while tamping at a specific pressure is, absolutely, a good habit to form in order to create a totally consistent system when pulling shots, it is in many ways an exercise in lip service.

a quick test to illustrate this theory-
grind and evenly dose/distribute a shot without tamping it. chances are, it will pull damn near exactly the same as a tamped shot. the puck will also look the same as if you tamped the living daylights out of it.

not to imply that tamping isn't a crucial part of pulling a shot. it keeps our gaskets cleaner, closes up channels and looks utterly cool. however, it's really all about proper dosing and distribution. if your doses are uneven, there's not a tamping method in the world that will save you.

so yeah, i'd put the whole "tamp with 30lbs of pressure" myth in the file right next to color blind dogs and goldfish with 2 second memories. find a tamping method that works for you and run with it. keep it level and consistent, and it's gravy.

way back when- italian baristas all tamped with 90lbs pressure. that was like, the standard back then. which makes us all total wussies anyway...
Yesterday I brought my scale to work, dosed and distributed two portafilters identically, then tamped one normally and the second with as much weight as I could.

The shot with all of my weight on it took two seconds longer to come out of the portafilter, but otherwise looked normal.

Two of my coworkers and myself all tasted the resulting espresso. The first double was sweet and smooth and exactly what we expected. The second one was too rich and had a harsh finish.

Thanks for showing the math Luis!
Yeah, as all are saying, it don't matter a bit. Elvin, Mike Cannon, and I just went and tested this... we pulled (multiple) control shots (10 - 30 lbs), and then a few shots without tamping at all, and then a few shots with 80+ lbs tamp pressure. We did these all as deconstructed shots and found that there was no difference. Channeling is more likely to occur in a zero pressure tamp, but 10lbs is more than enough to force out air bubbles that may be in an untamped puck. Otherwise, no difference, whatsoever.

And while we're at it, here's another myth to put to rest : Phil Collins did not actually ever witness a drowning or a murder or something like that. Mr. Collins made up the lyrics to "In the air tonight" on the spot cause he wanted something dark sounding.

Zak Rye - Italians at 90lbs? No way. They barely tamp at 5 lbs. They don't even put the pf on the counter.. they tamp holding it in their hand, and they like to make fun of Americans for our over zealous tamp styles.
If you've pulled enough shots with a naked portafilter, you've probably pulled some shots with overheated water and actually watched/heard the air being pushed through the puck before you start to see the first few drips. I have.

Jonathan Jarrow said:
Well said Jesse. I realize that the ambient air is O2, I have just wondered about it, since it is present in the puck at the time of extraction. To be quite honest, I sincerely doubt that it affects overall flavor in comparison to many of the other variables in espresso extraction. However, I'm just curious about any small effect that it may or may not be causing.

Jesse -D-> said:
Jonathan:

The ambient air is O2 and the gas that creates creama is CO2. This is where I disagree with your theory. The ambient 02 would be displaced by any water that entered the puck. When the oil and H2O emulsify, only then does the liquid (now espresso) have enough suface tension to contain bubbles. Water alone does not have the power to hold gas.
Re: 5lbs.

That's now. He was talking about "then". They did, in fact, USED to tamp at around 90lbs. Now days, it's barely at all.

Ian Shaughnessy said:
Yeah, as all are saying, it don't matter a bit. Elvin, Mike Cannon, and I just went and tested this... we pulled (multiple) control shots (10 - 30 lbs), and then a few shots without tamping at all, and then a few shots with 80+ lbs tamp pressure. We did these all as deconstructed shots and found that there was no difference. Channeling is more likely to occur in a zero pressure tamp, but 10lbs is more than enough to force out air bubbles that may be in an untamped puck. Otherwise, no difference, whatsoever.

And while we're at it, here's another myth to put to rest : Phil Collins did not actually ever witness a drowning or a murder or something like that. Mr. Collins made up the lyrics to "In the air tonight" on the spot cause he wanted something dark sounding.

Zak Rye - Italians at 90lbs? No way. They barely tamp at 5 lbs. They don't even put the pf on the counter.. they tamp holding it in their hand, and they like to make fun of Americans for our over zealous tamp styles.
Zak, I'd love to see you guys go for 90lb tamps. I think you could easily make a few more bucks in tips if you started jumping around while tamping. I missed ya on Monday dude :(.
Ian Shaughnessy said:
Yeah, as all are saying, it don't matter a bit. Elvin, Mike Cannon, and I just went and tested this... we pulled (multiple) control shots (10 - 30 lbs), and then a few shots without tamping at all, and then a few shots with 80+ lbs tamp pressure. We did these all as deconstructed shots and found that there was no difference. Channeling is more likely to occur in a zero pressure tamp, but 10lbs is more than enough to force out air bubbles that may be in an untamped puck. Otherwise, no difference, whatsoever.


Thanks for posting and for looking at this.

No difference at all? Gotta say I'm surprised. Sometimes rules are total bullshit, but many times they have a little basis in something factual.

Let me ask... no difference in time to extract the target volume? No difference in flavor? Also what machine were you using... was there pre-infusion involved?

I'm not challenging your conclusion... just looking for some detail. Again, frustrated by being 5 hours from my machine and unable to experiment in person.
Jason Haeger said:
Re: 5lbs.

That's now. He was talking about "then". They did, in fact, USED to tamp at around 90lbs. Now days, it's barely at all.

Aren't they the ones that put those stupid plastic noses on the front of their dosers for us to tamp with?
I tend to find a difference of flavor, but I think that's due more to compression and head space than actual tamp pressure.

It's the extraction time thing that I think doesn't really change. But there is more to extraction than time, and therein lies the difference(s). My $.02.

Brady said:
Ian Shaughnessy said:
Yeah, as all are saying, it don't matter a bit. Elvin, Mike Cannon, and I just went and tested this... we pulled (multiple) control shots (10 - 30 lbs), and then a few shots without tamping at all, and then a few shots with 80+ lbs tamp pressure. We did these all as deconstructed shots and found that there was no difference. Channeling is more likely to occur in a zero pressure tamp, but 10lbs is more than enough to force out air bubbles that may be in an untamped puck. Otherwise, no difference, whatsoever.


Thanks for posting and for looking at this.

No difference at all? Gotta say I'm surprised. Sometimes rules are total bullshit, but many times they have a little basis in something factual.

Let me ask... no difference in time to extract the target volume? No difference in flavor? Also what machine were you using... was there pre-infusion involved?

I'm not challenging your conclusion... just looking for some detail. Again, frustrated by being 5 hours from my machine and unable to experiment in person.
Using an FB-80 with pre-infusion, Mazzer Rober with a dose timer, 21 grams, 24-26 second extractions, six way deconstruction with total extraction volume around 1 oz. Coffee was our Big Truck blend.

There wasn't really a difference from 5lbs to 80lbs. I mean, the aforementioned math is 496 lbs hitting a 58mm, and since the pre-infusion probably eliminates the differences in initial head space there's not any physical reason why there would be a difference.

Brady said:
Ian Shaughnessy said:
Yeah, as all are saying, it don't matter a bit. Elvin, Mike Cannon, and I just went and tested this... we pulled (multiple) control shots (10 - 30 lbs), and then a few shots without tamping at all, and then a few shots with 80+ lbs tamp pressure. We did these all as deconstructed shots and found that there was no difference. Channeling is more likely to occur in a zero pressure tamp, but 10lbs is more than enough to force out air bubbles that may be in an untamped puck. Otherwise, no difference, whatsoever.


Thanks for posting and for looking at this.

No difference at all? Gotta say I'm surprised. Sometimes rules are total bullshit, but many times they have a little basis in something factual.

Let me ask... no difference in time to extract the target volume? No difference in flavor? Also what machine were you using... was there pre-infusion involved?

I'm not challenging your conclusion... just looking for some detail. Again, frustrated by being 5 hours from my machine and unable to experiment in person.
i think the general idea behind a standard tamping pressure is to ensure that all your baristi are regulating their doses. in other words, if you keep your espresso bean consistent, and know your 18g dose sits right at the ridge line on a portafilter basket with your standard 30lb tamp, then you will likely pull more consistent shots.

of course (as has been determined) tamp pressure between 10lb-80lb isn't a huge determiner of the espresso's taste. i've just always viewed it as a tool to keep everything consistent.

as a side note, i would imagine most people are tapping the portafilter during dosing to ensure the espresso settles? i usually do it on the top of the dosing chamber itself but i saw Gwilym Davies do it on the dosing fork at the WBC this year. that's one major factor i learned in sydney that helped my espresso go from shaky to good.

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