Tamper lighter with finer grind or tamper heavier with a coarser grind? - Page 2

Beginner and pro baristas share tips and tricks.
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Postby redbone » Dec 19, 2017, 8:02 pm

David, good point with regards to shape, surface and uniformity as opposed to just size.
Does seem logical when considering how they will fit together and intersect.
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Postby Charlene » Dec 19, 2017, 10:01 pm

HB wrote:I'm with Eric. If tamp pressure makes a difference, I've never noticed it. Not everyone agrees though.

Perhaps Kent Bakke could weigh in here on the subject?

What I offered was an observation of a sequence of events. That is what happened. One could readily extrapolate that there was a defect in what was thought to be a well groomed bed of grinds.

I leave the tamper pressure setting at 60 pounds and have done so for many months. I do that under Kent Bakke's advisement. Socratic Coffee proved doing so causes no defects. Is there any difference in taste between 30 and 60? Hard to tell. I would be surprised if there were. Is there a decrease in defective-pull incidence count? I would guess there is. How much is anyone's guess.


Postby bobroseman » Dec 20, 2017, 1:37 am

One can surmise that between 0 and some pressure (p1) there is a pretty dramatic change in shot quality. Then between p1 and some p2 the effect begins to diminish. Then beyond p2 there is no change in shot quality due to tamp pressure. Are P1 and P2 affected by the grinder, I wonder? Is P2 so low that any attempt at tamping is successful?
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Postby DrRoadrash » Dec 21, 2017, 1:03 pm

I've noticed no change in tamp pressure on time of extraction for fixed grind setting as long as there is an even distribution in the basket. For some time I was using a nutation tamp and that did significantly increase extraction time but I think that was more due to the fact that the nutation was correcting uneven distribution. If distribution is even I think tamp pressure has little to no effect, if it is uneven I think higher tamp pressure somewhat "corrects" the distribution and slows the extraction.

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Postby bluesman » Dec 21, 2017, 5:52 pm

DrRoadrash wrote:If distribution is even I think tamp pressure has little to no effect, if it is uneven I think higher tamp pressure somewhat "corrects" the distribution and slows the extraction.

I find that slowly increasing my tamping pressure over 15 seconds or so seems to help even out distribution. When you think about it, all those tiny particles can shift around to fill voids in the puck, unless & until they're mechanically locked in place against each other. Pinch a small pumpkin seed quickly between your fingers and it will be held there. Pinch it slowly and it will "squirt" from between them. So gradually increasing tamping pressure might logically help break up and shift clusters of ground coffee bits from denser spots to less dense unless they're already held firmly together & cannot physically break up and move. I suspect this is the major benefit of nutation and is of no value if (as you observe) distribution is already even.

Think of a basket full of particulate matter as a fluid rather than a solid, and the above makes more sense. We use fluid mechanics and principles to study blood flow, and blood is full of particles (red and white blood cells, immune complexes, platelets etc etc). Fluid is incompressible, as is a solid particle of coffee. So dense pockets of ground coffee within the puck will transmit tamping pressure if they're already locked together but shift & break up to relieve it if the clustered particles are still moveable against each other.


Postby CwD » Dec 21, 2017, 5:59 pm

I believe in tamping to full compression. If I can move the tamper further, I need to. If it won't move any further, I'm done.

More or less what's said here: https://baristahustle.com/blogs/barista ... d-you-tamp

I'm not sure it'd matter at all on a "straight to 9 bar" machine, where I suspect the pressure would compact it anyway. Since I do a pretty long low pressure preinfusion, I'd like to avoid any easy routes for water.

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Postby AssafL » Dec 21, 2017, 9:41 pm

I figure that if ramping pressure affects my pull at all it was because my basket prep failed.

In fact my first suspect in any bad (or odd) pull is basket prep. Be it WDT, grind, distribution or grooming.

I now find that grooming tools can help that quite considerably.
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