GlennT Senior Member Joined: 13 Feb 2012 Posts: 38 Location: SF Bay Area (Silicon Valley) Expertise: I love coffee
Espresso: Kraps Il Primo Steam Wanabe... Grinder: Baratza Priciso Drip: Aeropress & "Don't ask don't...
Posted Fri Apr 13, 2012, 1:55pm Subject: Why make such a big deal about tamping @ 30 pounds?
Many threads emphasize tamping at consistent pressure, sometimes even using a bathroom scale to "dial in" tamping pressure.
Frankly, I don't get it. I can understand tamping enough to assure the grounds are compressed a bit so they can expand again with the hot water. I understand the need to tamp evenly so the water flows through the PF without channeling through the side with less tamping pressure.
Why worry about Cup A tamped at 20 pounds vs. Cup B tamped at 40 pounds? A 58mm portafilter has ~ 4.1 square inch cross section. Tamping with 20-30 pounds force yields PRESSURES of 5 to 10 psi on the grounds. After that, the grounds get hit with hot water with at least 9 bar or 132 psi of pressure! Why care if the grounds get hit with 4 or 10 psi tamping when they'll just get hit with 130 or more psi of water?
Joel_B Senior Member Joined: 9 Oct 2007 Posts: 1,823 Location: Pacific NW Expertise: I love coffee
Espresso: Astra Mega II Grinder: Mazzer SJ, Virtuoso Vac Pot: Yama 5 cup Drip: nope, french press Roaster: Behmor, WP, BBQ drum
Posted Fri Apr 13, 2012, 1:58pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
Glen, im scratching my head along with you :-)
difference between 5lbs and 50lbs, yeah it will change the flow rate. Difference between 30 and 35lbs, nah. It got started then regurgitate. As long as you're tamping linear and relatively repeatable pressure you're good.
PS. Kudos to you for questioning it in the first place. Taking advice from more experienced is great, but at some point we need to know why we're doing what we're doing.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,671 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Fri Apr 13, 2012, 2:00pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
No, here we (edit, well me anyway) advise to only be consistent, regardless if you use 20 or 50 pounds, just be consistent and all is well. A lot of new people get hung up on tamping and like you said, the exact number is no big deal.
30# is offered as a good rule of thumb, a place to start. Using a scale allows you to be consistent, thats all.
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Fri Apr 13, 2012, 2:17pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
I just saw a video of two 5 year olds making espresso, and tamping it themselves, and I doubt those two reached even 20 pounds of pressure, and still they managed to pull a decent shot. So tamping really doesn't matter as much as people think it does.
Posted Fri Apr 13, 2012, 2:21pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
There is a lot of left over flotsam and jetsam from years ago about tamping force. It use to be 35 pounds. It has been shown that anything from 15 to 55 pounds will work great. One respected pro barista weighing in at (well) over 225 pounds says to do a "handstand tamp" (feet off the floor). And really, if you are in the 30-50 pound tamping pressure range it will be fine, and you don't even have to be that consistent. Try this- get out the scale and tamp on it. Press down with a SLOWLY increasing force, watching the scale's display as well as the movement of the tamper into the basket. Also, pay attention to the "feel" of the compression. You WILL find that after about 30 to 35 pounds nothing (or VERY little) happens. Tamping level counts as exponentially more important than the force used. My current universal advice is that if you find you HAVE to tamp at a very low pressure (less than 10 pounds) or at a very high pressure (over 60 pounds) then you are compensating for other factors that need to be addressed.
JasonBrandtLewis Senior Member Joined: 9 Dec 2005 Posts: 6,098 Location: Berkeley, CA Expertise: I live coffee
Espresso: Elektra T1 - La Valentina -... Grinder: Mahlkönig K30 Vario -... Vac Pot: Yama 5-cup Drip: CCD, Chemex Roaster: No, no, not another...
Posted Fri Apr 13, 2012, 4:46pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
Generally . . . in my experience . . . the more experienced people on this site never say "You must tamp at 30 pounds." Rather, they say, Be consistent in your tamp.
I've had great shots with virtually no tamp at all, and when it appeared the barista tamped the proverbial heck out of it . . . I don't have a clue what I do, in terms of pounds of pressure per square inch. It's all muscle memory: I tamp, it feels right, I stop.
MARIOBARBA Senior Member Joined: 26 Sep 2011 Posts: 126 Location: MONTREAL CANADA Expertise: I love coffee
Espresso: Ascaso DUO Prof TRONIC Grinder: Baratza Vario
Posted Fri Apr 13, 2012, 5:20pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
In Italy, and in Italian coffee bars here in Montreal, baristi don't even use a tamper. They simply use the plastic appendage on the grinder's doser to level the coffee with an upward motion and lock in the portafilter. They've been doing it that way since espresso was invented and it was good enough for people all over the world to want to emulate it. IMO tamping is over rated, I usually just use the tamper to make sure I have an even puck, I hardly pit any pressure at all.
But hey, whatever works for you.
Gandhi once said that there are as many Hinduisms as there are Hindus, I guess that there are as many barista techniques as there are baristi.
Posted Fri Apr 13, 2012, 5:52pm Subject: Re: Why make such a big deal about tamping @ 30 pounds?
I think it depends on the dose ... at least it seems to me, on my gear.
For example ... if I were to put ... say 10-12 grams of coffee in a standard double basket there would be a big difference between tamping and not tamping -- because the loose coffee would have all that room to move around in a slurry as the water hits it while a really solid tamp would hold the coffee powder into a puck shape for a longer time with just the top layer getting "soupy"
But if I put 16-18 grams in there - it would get compressed just by pressing the coffee against the shower screen to lock the PF - and there wouldn't be much difference between tamp and no tamp. The coffee would be confined between the bottom of the basket and the shower screen and wouldn't be able to move around even though not tamped firmly ... plus as it swells when the water hits it, that will press it even more tightly into its confined space.
I think 5 is pretty low. Whether 5 pounds is sufficient would depend on a lot of other factors, such as: - head room - quality of the grind (some grinders create a fluffy grind in a narrow particle range that seems to compress easier) - depth of dose in basket - dose - water distribution - if the machine has pre-infusion - pressure ramping profile
There's one way to find out! Well.. maybe two. ;-)
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