Now that I've got your attention.... :grin:

Brady and I decided that this weekend has been kinda slow on BX, so I thought I would generate some controversy. Please consider the following:

We performed an experiment at Counter Culture's Training Center during the Southeast Regional Barista Jam based on an observation made by Brent Hall. He mentioned that the 30 or so pounds of pressure exerted by the barista while tamping the dose in the portafilter was essentially negated due to the extreme pressure placed on the puck during extraction. In other words, your espresso machine has bigger muscles than you. Other than channeling, why bother then? So we tried it, dosing into the portafilter, leveling, and then, skipping the tamp, locking into place and pulling the shot. It worked.

Now, is it consistent? I doubt it, but that would depend on the barista, same as the tamping procedure.

The question that arises in my mind is this: have we given the proper importance to the leveling process, as this is where we deal with clumps and allocating the coffee evenly in the portafilter?

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Also...

Eric said:
Dissolved solids = muddy.

Not really. I think by "muddy" Paul meant "wet and not as solid" after the extraction was complete. As I recall, this has more to do with the expansion of the puck and how much room it had as the shot completed. If it had grown to the point that it met the dispersion screen you'd have a more compressed and "drier" cake. If it expands less and has room to spare, it will not form as solid of a puck AND that room will be taken up by water, which will remain on top of the puck after the pump cuts off.

Were they muddier or just messier? Messier, I understand... Will pull some more shots tomorrow and see what I can see...
You are correct, Brady. I was referring to the appearance of the puck. However, I am recalling that we did this experiment following the class on "Dialing in Espresso" where we had broken down the espresso blend into its component bean varietals, in order to understand the taste and structure of the espresso shot. As I recall, at least one of those varietals, the Gayo, was a washed process bean, and may have been what we were grinding to perform this experiment. Which means that even with tamping, the puck looks muddy with water remaining on top of the puck after the pump is cut off. A natural or pulp natural would have a drier puck.
I think this is arguably the most important part of this discussion. Every time I have tried experiments with tamping the two things I always find to have the most significant change is flow-rate/time (especially within the first ten seconds), and the rate at which liquid (at the bottom of the basket) goes from no flow to maximum allowable flow based on particle size (grind). These are two very similar and linked concepts, however they are different.

Though an extraction may seem to pull in the same amount of total time no matter the tamp pressure, the first ten seconds or so are noticeably different. I believe this has to do with the variance in pressure between what the pump is putting out, what is between the group and the puck, the atmospheric pressure that the espresso is ultimately flowing into, and the effect of the puck's beginning density has on the relation between the previous three (like Fraser has similarly stated), but I also could be way off base.

What this means scientifically... I'm not sure... yet. What this means to my tongue... generally tamped shots taste more developed, and, well, better (I know, kind of a generic descriptor, sorry).

Fraser Jamieson said:
Take the portafilter out of your machine. Start the machine. Read the pressure gauge. Well, it probably says 9 Bar, but there is currently 0 psi at your head. Without resistance, there is no pressure.

The way to measure post puck pressure is to use a spoutless portafilter with a line pressure gauge screwed onto it. The density of the puck will change the dwell time of the pressure rise.

If the coffee is lightly packed, it will easily allow water flow at less than 1 Bar. The machine has 9 Bar "available" but that's not what's happening in the portafilter.

My experiance is that it tastes better when tamped. But...I've tried it and also been pleasantly surprised.

I'm still a tamper fan.

Paul Yates said:
James raises another question, and I don't think we've answered it. Why does the untamped puck look so muddy and messy, as compared to the tamped puck, if the pressure placed by the group head is the same? Does tamping regulate bloom? Does it affect how dry the puck is afterwards?
As a newbie to baristadom, I find this very interesting and some the experiments I have yet to try. Just tasting the difference sounds like fun. Difference between tamp and no tamp. In my beginnings with my spro machines I thought that one of the major reasons for tamping what keep the mess to the group head to a mimimum. I see now there is way more going on with the man behind the curtain, so to speak.
Thanks Paul
Nice way to get our attention Paul. "Throw away your tamper" Sounds like throw away your Bible.
Yean, I figured it would be like cutting my arm while swimming in the shark tank....nothing like blood in the water to get the sharks excited! Plus, I like to get my geek on every once in a while, and what we've been discussing is serious geek-territory. Like, I didn't understand hardly anything Andy just said, but that's because I am a newbie, also. But I am geek enough to gnaw on it until I do understand it. Ok, I have used the word "geek" way too often in a positive light...this is frightening!
Hey while we are at it, lets all use old coffee,
that was roasted months ago ...and move to super autos! Oh wait the Mermaid already does that. I feel better since I let my inner shark boy out!
Andy Atkinson said:
Though an extraction may seem to pull in the same amount of total time no matter the tamp pressure, the first ten seconds or so are noticeably different. I believe this has to do with the variance in pressure between what the pump is putting out, what is between the group and the puck, the atmospheric pressure that the espresso is ultimately flowing into, and the effect of the puck's beginning density has on the relation between the previous three.


This is a more in depth at basically what I was trying to get at when i said "But, the fact still stands that water will take the path of least resistance (ie channeling.) No matter how well you think you are dosing and leveling your un-tamped puck in the basket, there will be gaps from where the espresso has not settled, creating spots where more water, and therefore more dissolved solids, will pass through the puck in the early stages of shot extraction. Tamping takes out the likely-hood of channeling and the guess work, giving you something that you can for sure say, that shot was evenly distributed and packed and will not have any channeling because i took all the guess work out." But to elaborate on it, I dont mean channeling in the sense that there are huge fissures or that the puck would largely be lopsided, but more in a sense that without the tamp eliminating the gaps the water flow will change the extraction in the beginning. But by the middle to end of the extraction the same rules for a normal tamped extraction will take place because of the bloom and such...
Geek is good. Geek is good. Leak is bad, leak is bad, Geek is fun and good. There I said it too much too. Now Paul can you say "Coffeee Geek"
Wear the badge with pride...
Joe
for me the uniform cup quality is the most important. i don't think one step is more important than the other ones. all important:
Doseing uniformly, distributing uniformly, leveling and tamping uniformly. I beleive, this is the way to have nice steady shots.

even so i drank very good espresso from a barista who didn't paid too much attention to their preparation technik and tamped neglectful. That was good, but i think that "quality" was not so conscious. (and consistent)

anyhow, i like tamp!
Mike said:
Hey while we are at it, lets all use old coffee,
that was roasted months ago ...and move to super autos! Oh wait the Mermaid already does that. I feel better since I let my inner shark boy out!

Got something useful to add here, Mike?
Eric said:
(snip)...But to elaborate on it, I dont mean channeling in the sense that there are huge fissures or that the puck would largely be lopsided, but more in a sense that without the tamp eliminating the gaps the water flow will change the extraction in the beginning. But by the middle to end of the extraction the same rules for a normal tamped extraction will take place because of the bloom and such...

OK, that makes more sense. So not channeling as much as a more rapid flow of water through the puck initially. Will have to play with this with specific attention to the flow rates at different times to see if that holds water (no pun intended).

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