To tamp or not to tamp - Page 3

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peacecup (original poster)

#21: Post by peacecup (original poster) »

Noel,

If you have some time and a little coffee to burn, try a simple experiment (which I have not done so far!). Get a coarse, hard-tamp shot dialed in, and a fine, light-tamp shot dialed in. You'd need to use two grinders, or at least get the settings pre-determined. Next, just pull the two shots - in you case you could do so simultaneously on the 2-group Lusso. It would be interesting to hear your results. I may try to do so myself when I get my next batch of fresh beans. I'll just set up two different hand grinders, and do a mini taste test.

I have not read where many folks have really given much effort to dialing in a coarser-ground shot. If you use the "tamp as hard as you can" approach, you will dial in the coarsest grind that will give an ~ 30-sec shot. I know, because I used this method when I first got my Export. I gradually gone to a finer grind under the (untested) hypothesis that a finer grind will give a better extraction. At this point it is rare that I can't adjust my tamp "on the fly", i.e. by judging the dose, bean, etc., and get a good pour from most any grind. If my grind looks finer than it should I tamp more lightly, etc.

It seems to me its just as easy to be consistent with a hard tamp as it is with a light one. It may be that one needs to experiment with each bean/dose combination to get a pour suitable to ones taste.

RE; your post, I'm not sure about the hydrodynamics. It seems to me that a non-compacted mass (ie light tamp) would be very unstable when first exposed to the brew water, and that the surface layers at least would be disturbed. I've always assumed that this would lead to channels being formed in the "puck", causing an uneven extraction. A firmly-tamped a polished surface would act as a buffer, allowing the puck to remain intact while water slowly infuses it. Think of an earthen dam being hit by water, for example, vs. the same pile of earth that was not compacted. All untested theory....

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

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narc

#22: Post by narc »

PC, there is one "problem" with the Ponte Vecchio Lusso 2(PVL) in running a grind/tamp side by side. The problem has been consistent no matter what blend or SO coffee I have been using. The left group always pulls a slightly sweeter espresso. Why? Not sure. The flow volume/time out of an empty portafilter is pretty much identical if you time from when the water 1st appears to the set volume. The difference is when the water first appears relative to the lever postion. I'm assuming that might be the reason. The way I pull shots on the PVL is: Pull the lever down, hold for a 3-4second count preinfusion, release, wait until the first drops appear in 1-2 seconds, pull and release. Have not figured out, actually too lazy to figure out a way to compensate for the difference between the two groups. I look at the slight differences in taste as a positive since it's not a worse taste in the right or left group. Just a bit different.

I have on order from Vaneli's a bottomless portafilter. When it arrives I will try the two extremes of tamps. #30 and a light kiss of a tamp.
LMWDP #151

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narc

#23: Post by narc »

This morning using the new "Newd" portafilter I progressively increased the tamp pressure and fineness of grind. I know two variables make the following observation semi- meaningless. Actually 3 variables. I'm pretty sure the dose was increasing with each shot. The element I left constant was the clearance between the coffee and lip of the basket. The machine was the MicroCasa a Leva(MCaL). 1st shot was a sinker. Not sure if it was a dose, distribution, tamp or all the factors. Uneven extraction. 2nd shot, 1/2notch on the MazzerMini finer, little heavier tamp. Looked good extracting. In terms of taste subpar. For me another sinker. 3rd shot, 1/2 notch finer and harder tamp. Looked good extracting. Taste acceptable. 4th shot, full notch finer and full #30 tamp. Shot extracted how I was hoping for. 3-4 sec preinfusion, drops appeared 2-3 seconds after releasing lever, nice looking extraction. Taste for this 50:50 blend of India Mallali:Mexico Oxaca was very acceptable. More intense flavors, darker & thicker crema. I think I'm back to a heavy tamp on MCaL. Starting to feel little schizo when it comes to pulling shots.

Prior to the MCal shots I pulled couple light tamp shots with the same blend on the Ponte Vecchio Lusso (PVL). The grinder was set at the MCaL pull #3 with a light tamp. Both shots were acceptable. The PVL characteristic heavy, thick crema and sweeter bias obscuring some of the subtle flavors pulled on the MCaL.

Maybe I need to change the headspace on the MCaL to the 6mm space I leave on the PVL for a lighter tamp on the MCaL. I'm really confusing myself. Too much thought. Paralysis by analysis is setting in.
LMWDP #151

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AndyS

#24: Post by AndyS »

narc wrote:The boiler pstat is set at 1.0 +/- 0.05 bars. So the maximum pressure at preinfusion would be ~29.4 psi(1atm + 1.05 bars).
No, actually the max pressure on your puck at preinfusion is ~15.2 psi (1.05 bar). Atmospheric pressure is present both above and below the puck, so it cancels out.
narc wrote:Considering the linear water flow that hits the puck initially at a low pressure maxing to the 1.05 Bars would not the puck be basically "tamped" by the water pressure to ~30pounds?
No again, 1.05 bars on a 58mm diameter puck is equivalent to about a 60 lb tamp (~15 psi x ~4 sq inches).
-AndyS
VST refractometer/filter basket beta tester, no financial interest in the company

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AndyS

#25: Post by AndyS »

I just find this whole subject pretty funny because with my coffee, my machine and my technique, tamping pressure makes almost no difference in shot timing.

In other words, I've repeatedly compared shots tamped at 10 lbs with shots tamped at 60 lbs and found little or no difference. When people say they instinctively "correct" a grind that's a little too coarse by tamping harder, I just scratch my head, knowing it would make no difference on my setup.

Does it have to do with the fact that I dose low (13-14g) in a double basket? Is it the line pressure preinfusion that I use? Is it the fact that I am too dumb to notice the difference? I'm not sure, but it's an endless source of amusement for me to read all the fuss made about tamp pressure.
-AndyS
VST refractometer/filter basket beta tester, no financial interest in the company

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HB
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#26: Post by HB »

AndyS wrote:Does it have to do with the fact that I dose low (13-14g) in a double basket? Is it the line pressure preinfusion that I use? Is it the fact that I am too dumb to notice the difference? I'm not sure, but it's an endless source of amusement for me to read all the fuss made about tamp pressure.
Probably the first two are true. I have no way of proving it, but my WAG for pump extractions is that the tamp pressure affects the efficacy of the initial wetting and thereby impacts the puck expansion. For multiple lever pulls, I assume the puck is almost a slurry between strokes and is then re-compacted by the force of the water itself. Anyone got a transparent basket and some dyes to confirm?
Dan Kehn

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peacecup (original poster)

#27: Post by peacecup (original poster) »

Andy - can you choke your machine with a fine grind? Try keeping a good 30# tamp, and tightening up the grind until you completely choke the machine. Then use the same grind and don't tamp at all, just level it with the tamper (you will probably need to adjust the dose to leave approx. the same headspace after tamping/leveling). Does the machine still choke using the same grind fineness but no tamp?

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

grong

#28: Post by grong »

AndyS wrote:I just find this whole subject pretty funny because with my coffee, my machine and my technique, tamping pressure makes almost no difference in shot timing.
On my percolator, I mean espresso set-up, varying tamp pressure with the grind remaining constant has a noticeable effect on the flow rate and final product. I can slow it down or speed it up with varying pressure. I imagine that I fine tune the tamping pressure minutely to create an ideal extraction. This greatly enhances the entire experience. Slower shots are heavier and more syrupy, faster pulls illuminate more elaborately the subtle flavor distinctions.
HB wrote:For multiple lever pulls, I assume the puck is almost a slurry between strokes and is then re-compacted by the force of the water itself. Anyone got a transparent basket and some dyes to confirm?
In my imagination I apply the Heisenberg principle and the puck remains in perfect formation during multiple pulls, which is why, I think, I think the espresso tastes so good. I like the double pull easily as much as the single pull, though they do taste different, the single being fluffier and purer, the double more daring and worldly.

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AndyS

#29: Post by AndyS »

peacecup wrote:Andy - can you choke your machine with a fine grind? Try keeping a good 30# tamp, and tightening up the grind until you completely choke the machine. Then use the same grind and don't tamp at all, just level it with the tamper (you will probably need to adjust the dose to leave approx. the same headspace after tamping/leveling).
Well sure I can choke it with a fine enough grind.

As far as your test goes, I'm with you up until you adjust the dose. One can't test the effect of differing tamps if the dose is also changed.
-AndyS
VST refractometer/filter basket beta tester, no financial interest in the company

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peacecup (original poster)

#30: Post by peacecup (original poster) »

Well Andy, you don't need to adjust the dose. Just grind down until you choke the machine with a standard tamp pressure, then use the same grind but don't tamp. The headspace will be less is the point.

RE: Dan's assertion that the puck becomes a slurry during multiple pulls, this is not always so. With moderate (~10#) tamp on the Ponte Vecchio the puck will remain entirely intact during two or more pulls if the dose if the grind is relatively coarse and the basket full (but not necessarily touching the screen). I can say this for certain because there is no way that the solid pucks I eject from my double basket could be compacted by the piston pressure. I see I need to post some photos of these.

And this brings us back to one of the points of the thread, and is relevant to Andy's original question. I initially went with a coarser grind/harder tamp because I wanted to use a very full (but not touching) double basket (i.e. maximum dose) on the PV. This comes out around 15g, maybe more. If I fill the basket that full with a finer grind it will always choke the machine, so I needed to back off. So one reason to use the coarser grind is to get the maximum dose possible, and therefore a greater volume of espresso per shot. I've since reduced my dose requirement, so a finer grind is possible.

I do plan on running some informal taste tests ASAP between the two.

PC

PS, Andy, I do know Richard C, but mostly by reputation. He is a tireless advocate for preserving the last great wilderness in North America, the Tongass National Forest.
LMWDP #049
Hand-ground, hand-pulled: "hands down.."