Finer grind, lighter tamp or coarser grind, harder tamp?

Beginner and pro baristas share tips and tricks for making espresso.

#1: Post by Ricci »

What's more prone to channeling?

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#2: Post by HB »

The tamp is at the bottom of my list of channeling culprits. Whether you prefer hard or light tamps, it doesn't matter, just be consistent. The actual grind setting doesn't come to mind as a contributing factor either, except for really fine grinds for ristrettos, which require solid puck prep to avoid channeling since the flow rate is so slow.

Channeling causes are more likely (a) stale coffee, (b) uneven puck prep, (c) poor quality grinder, and (d) "unforgiving" espresso machine. There are kludgy workarounds for (d) such as lowering the brew pressure with deeper baskets to lengthen preinfusion time by increasing puck-to-shower-screen clearance as well as equipment-specific tricks (e.g., initially opening the steam wand valve on a single boiler espresso machines to temporarily decrease brew pressure). There's no fix for (c) other than upgrading.

On a related note, I'm reminded of this sad truth noted by Jim long ago (2007) in Umpteenth inexpensive grinder thread:
another_jim wrote:Newbies invariably attribute their inability to pull two identical shots in a row to the lack of sufficient equipment settings they can change between shots. The fact is that the entry level equipment used by newbies is much more unforgiving than the commercial equipment people buy after they decide they'll pursue home espresso. This creates a double whammy, the people with technique good enough to use entry level equipment have moved beyond it; and the people buying it will have their weaknesses mercilessly exposed. The upshot is that entry level equipment gets a lot of unfair criticism; and that newbies get a very long hazing learning to cope with it.
Dan Kehn


#3: Post by Nate42 »

Forget about trying to use your tamp as a flow control variable. Focus on tamping consistently. I suppose if you did a hand stand tamp it could fracture the puck and lead to channeling, but the simple solution there is don't do that. I find the easiest way to tamp consistently is just push until the puck is fully compressed - ie "push until it pushes back". This doesn't require anywhere near the 30lbs of force that used to be considered standard.

As to grind, too coarse a grind may well reduce channeling, but that's small consolation if your result doesn't taste good. Too fine a grind can contribute to channeling, but if you need a grind that fine for good extraction of a particular coffee, you have to find a way to deal, which is why long preinfusion and pressure profiling is a thing. You need to dial in your grind by taste, and focus on good puck prep to minimize channeling.

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#4: Post by mgrayson »

Some baskets are more prone to channeling than others. I found VST particularly difficult, but that was not a universal response.

It's a less expensive experiment than upgrading the machine.

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#5: Post by cafeIKE »

No, if a basket consistently channels, the dose/grind is incorrect for that machine / basket combo.

IMO, basket [and tamper] chasing is only effective for a small subset of available coffees. Get a coffee/machine/basket dialed and you are good to go... until next week/month/year.

Some coffees are amazingly stable and others will require constant futzing.

Other than level, tamping is irrelevant, both pressure and shape, except in a small subset of dose/screen interfaces.
Grind controls the flow rate.
Distribution trumps both grind and tamp.
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#6: Post by Jeff »

The only thing I would add is that VST and other high-flow baskets tend to be demanding on both prep and grind quality. Unless you've got the technique and gear to take advantage of them, they can make your espresso worse. The EPNW HQ 14 (doses like an "18") is an example of a high-quality, yet forgiving basket. There are others as well.


#7: Post by DamianWarS »

Ricci wrote:What's more prone to channeling?
tamping techniques are no longer a conversation with the exception of keeping it level and being consistent. from what I understand hard or light tamps don't have enough impact to matter so just tamp consistently. Nutating tamps perhaps are the exception but they are wildly inconsistent and to be honest, even a perfectly executed nutating tamp I can't see being evenly distributed and it will probably leave areas more jammed and others unaffected which will only promote channels. if you want to decrease the resistance of the puck with a fine grind and increase the resistance with a coarser grind (outside of grinding coarser/finer) I would dose down/up to accomplish this rather than attempting to tamp lighter/harder.


#8: Post by exidrion »

Jeff wrote:The only thing I would add is that VST and other high-flow baskets tend to be demanding on both prep and grind quality. Unless you've got the technique and gear to take advantage of them, they can make your espresso worse. The EPNW HQ 14 (doses like an "18") is an example of a high-quality, yet forgiving basket. There are others as well.
I bought IMS baskets because they were the only ones available from a local store here, not knowing this. Personally, although I have been having more channeling, I feel like it's a good way to improve because you do have to be so meticulous :mrgreen:

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#9: Post by cafeIKE »

Jeff wrote:VST and other high-flow baskets
How does one determine a high flow basket :?:

Changing the dose ±¼g or the grind ±0.0015mm can change the flow and taste significantly.

It is the INTERACTION of Coffee*, Grind, Group, Screen and Basket not necessarily in that order which determine flow AND TASTE.
Put another way, local experiences may not mirror remote.

* In an SO roast, not all beans taste the same. Try crunching a few and see how they can differ. Some coffees are more variable than others. In a 60/40 blend, it is fairly certain not all shots contain the same proportion of each component, each bean of which varies from its neighbor. In a complex blend, variation could be higher. [We've all shaken the cashew tin to get the whole nuts and shift the broken bits to the bottom. :oops:] IMO, WDT** as much as distributing also homogenizes the vagaries further reducing potential problem area.

** For whatever reason, the Niche anti-popcorn bean feed disk retired WDT here.


#10: Post by DamianWarS »

cafeIKE wrote:How does one determine a high flow basket :?:
this would seem to be a simple test. take a basket with a claim of high-flow with one that does not have this claim and start pulling shots with them. it's an interesting idea however to change the basket for a higher flow shot or conversely a slower shot