Tamp pressure does matter

Beginner and pro baristas share tips and tricks.
Charlene
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Postby Charlene » Dec 18, 2016, 2:45 pm

Watched a video last evening which lead to making a software controlled pressure adjustment on the PuqPress.

This Scott Rao video presents an extraction flaw wherein the start of extraction was not uniform across the bottomless portafilter screen rather, it started along the outside edge on one side.
In my case, it was the edge closest to the portafilter handle.



After first ensuring the grinds were indeed uniformly distributed prior to tamping, the problem remained. Then, a corrective action was taken to increase the tamp pressure from 30 pounds to 32 pounds.

That was just enough tamp pressure increase to eliminate that problem.


...split from PuqPress Automatic Tamper Rocks! by moderator...

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Viernes
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Postby Viernes » Dec 21, 2016, 10:33 am

Charlene wrote:After first ensuring the grinds were indeed uniformly distributed prior to tamping, the problem remained. Then, a corrective action was taken to increase the tamp pressure from 30 pounds to 32 pounds.

That was just enough tamp pressure increase to eliminate that problem.


Are you sure about that?

I really don't think you're going to solve any problem only with tamping 2 pounds harder...

Don't get me wrong, I have a Puqpress and I love it. But commenting on such "solutions" sounds a bit "magical".

Charlene
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Postby Charlene replying to Viernes » Dec 21, 2016, 3:29 pm

Hi Viernes,

Achieving a perfect cup of espresso seems to be a bit magical. Don't know if that is possible for many home batistas including, moi.

It's the challenges of the quest that inspires.

With all other variables at nominal, if the grinds are inadequately distributed, adding several pounds of pressure is not likely to overcome uneven infusion but... it may improve the outcome to some degree.

The ability of adding or subtracting a precise pressure change value on the tamper is there for the using.

In the case I cited, adding two pounds worked. It overcame an apparent defect in my method of grinds distribution.

With that problem identified, what I did was to go in search of information to improve my method of distributing grinds in the portafilter before tamping and discovered a documented method to improve it.

I tried it and indeed, an improvement was achieved (stirring the grinds with a thin probe such as a dissecting needle).

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redbone
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Postby redbone » Dec 21, 2016, 3:57 pm

I think many use to believe it was about magic but many here including recent work done by John of D.E. is showing that it's a science as much as it's an art. Ratios, consistency and managing variables are a greater part of the equation in making a perfect cup. Some machines are more forgiving with regards to tamp pressure than others.
I highly doubt all variables being equal that anyone could taste the difference in the cup between 30lbs or 32lbs of tamp pressure.

There has been some testing done on this by Socraticoffee that concluded "Tamping pressure, in the given range we assessed (5-20 kg) yielded no significant impact on TDS nor did it significantly impact the extraction itself". http://socraticcoffee.com/2015/07/the-impact-of-tamping-pressure-on-espresso-extraction/
ON A QUEST FOR BETTER ESPRESSO


Rob
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HB
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Postby HB » Dec 21, 2016, 5:53 pm

redbone wrote:There has been some testing done on this by Socraticoffee that concluded "Tamping pressure, in the given range we assessed (5-20 kg) yielded no significant impact on TDS nor did it significantly impact the extraction itself".

That's consistent with other reports I've read over the years. Michael Teahan reported at the SCAA conference that he found no difference between a 30 and 300 pound tamp (my searches indicate it was part of his presentation "Fundamental Principles of Espresso Machine Design", but I have not found a copy; anyone know if it's online?).

Charlene wrote:In the case I cited, adding two pounds worked. It overcame an apparent defect in my method of grinds distribution.

To demonstrate that's the cause, prepare two identical baskets, one tamped at 30 pounds and the other at 32 pounds. Mark one of the baskets on the underside for later identification. Place the baskets on a lazy susan and spin it several times without looking. Now pull two espressos and pick your favorite. Repeat at least 3 more times. If you pick the one tamped at 32 pounds every time, you've demonstrated the cause. If you don't get it right every time, see A note on comparison tests for how many trials with correct identification are required to demonstrate statistical significance.
Dan Kehn

mike guy
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Postby mike guy » Dec 21, 2016, 9:34 pm

Another resource on tamping pressure. Maximum density pressure seems to indicate minor pressure adjustments wouldn't matter.
https://baristahustle.com/how-hard-should-you-tamp/

chrisbodnarphoto
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Postby chrisbodnarphoto » Dec 21, 2016, 10:36 pm

redbone wrote:There has been some testing done on this by Socraticoffee that concluded "Tamping pressure, in the given range we assessed (5-20 kg) yielded no significant impact on TDS nor did it significantly impact the extraction itself". http://socraticcoffee.com/2015/07/the-impact-of-tamping-pressure-on-espresso-extraction/

As discussed earlier in the thread, they DID admit that a change in flavour was still possible. TDS doesn't equate to flavour profile, so there is some suggestion that flavour/taste and tamp pressure could still be directly correlated ... or, in the very least, the theory has yet to be proven otherwise.

Charlene
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Postby Charlene » Dec 21, 2016, 11:05 pm

Hi Dan,

The study rebone cited was in reference to what he apparently thought I was implying.

All things being equal, I see no way that extra tamping force could make a shot better tasting unless it lessens distribution defects hidden from view beneath the surface of the grinds.

What I empirically witnessed was the effect of additional tamping force overcoming grinds distribution defects in my portafilter basket.

Does not, tamping have a distributive effect on empty spaces within the grinds?

Here's an experiment...

Have a group of baristas do an 18 gram dose in their hidden-marked portafilter then do a blind swap between themselves, then each tamp and return the portafilter to its owner for brewing and see how the shot compares with each barista's previous shots.

If each of us subconsciously, over time, zero in on the pressure we use that is associated with good shots, the tamping force has been calibrated to what typically lies in our own personally prepared grinds in the portafilter, not someone else's.

I am starting to visualize aspects of tamping, tampers, and those who tamp... with putting, putters, and those who putt. I LOVE the game of golf and its traditions. I played golf for many years and was part of that culture but the home barista community is new and different.

Could be, I unknowingly stepped on sacred ground for ever posting this post.

HB wrote:That's consistent with other reports I've read over the years. Michael Teahan reported at the SCAA conference that he found no difference between a 30 and 300 pound tamp (my searches indicate it was part of his presentation "Fundamental Principles of Espresso Machine Design", but I have not found a copy; anyone know if it's online?).


To demonstrate that's the cause, prepare two identical baskets, one tamped at 30 pounds and the other at 32 pounds. Mark one of the baskets on the underside for later identification. Place the baskets on a lazy susan and spin it several times without looking. Now pull two espressos and pick your favorite. Repeat at least 3 more times. If you pick the one tamped at 32 pounds every time, you've demonstrated the cause. If you don't get it right every time, see A note on comparison tests for how many trials with correct identification are required to demonstrate statistical significance.

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redbone
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Postby redbone » Dec 22, 2016, 9:35 am

chrisbodnarphoto wrote:As discussed earlier in the thread, they DID admit that a change in flavour was still possible. TDS doesn't equate to flavour profile, so there is some suggestion that flavour/taste and tamp pressure could still be directly correlated ... or, in the very least, the theory has yet to be proven otherwise.


That may or may not be so but I highly doubt a 2lb difference in tamp pressure can be detected in the cup based on any study I've read or trials done at home. Even less chance a difference in taste can be detected when changing tamp pressure from 30lbs to 32lbs.

* A discussion on tamp pressure is an entirely separate thread best discussed elsewhere. This thread was about the PugPress of which I've voiced my opinion and no longer care to further promote or discuss. Carry on and enjoy.
ON A QUEST FOR BETTER ESPRESSO


Rob
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Charlene
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Postby Charlene replying to redbone » Dec 22, 2016, 12:03 pm

In my considered view, a discussion on tamp pressure has everything to do with this post.

I innocently, but for good reasons, chose to go with what I have come to realize is a controversial tamping route by buying this tamper I am bound by it now to dial in a tamping pressure that works right for the grinds I personally create in my portafilter.

We all experiment in the beginning with tamp pressure in learning the craft of espresso making, right? I am no different.

You made a false determination as to my motives for posting this post.

 
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