Doser Accuracy - Page 3

Grinders are one of the keys to exceptional espresso. Discuss them here.
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#21: Post by HB »

Dan Kehn

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#22: Post by RegulatorJohnson »

in my esperience (espresso experience) i have found that clumping is related to surface oils on the beans. no surface oil (dry beans) no clumps, slimy, oily beans will give me the clumps every time. some beans start out dry then age and begin to show surface oil. these beans don't clump at first, then they do clump when the oil is present.

that what happens for me. YMMV.

2012 BGA SW region rep. Roaster@cognoscenti LA

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#23: Post by Fullsack »

I have found that I can better compensate for the age of the beans by increasing the amount of beans that I grind rather than making the grind finer. At least that tends to be true with the Ponte Vecchio Lusso I have been using.
LMWDP #017
Kill all my demons and my angels might die too. T. Williams

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cafeIKE (original poster)
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#24: Post by cafeIKE (original poster) »

Since I came into a LOT of stale coffee recently :(

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#25: Post by malachi »

cafeIKE wrote:Clump breaking, Stockfleth's move, 30# nutating tamps, PF tapping, puck polishing, etc. are pretentions. Espresso survived a very long time without them. Their introduction has done nothing to improve consistency, especially in shops where far too much emphasis is placed on the 'show'. Perhaps paddle-thwacking begat them all?
I have to call full-on bullsh** on this.

I'm sorry - but I've never had a shot in Italy of the quality of the best shots in Scandanavia, Australia and the US. Sure... it's hard to get undrinkable espresso in Italy (and easy to get that in the US). But great shots? No comparison.

Because in Italy "drinkable" is good enough.
Espresso is a cultural icon - and a tradition - and you don't change that sort of thing.

Outside of Italy - people are trying to push things forward because they are not hide-bound traditionalists.
cafeIKE wrote:When a doser is used as designed, a volume of coffee is dropped in the basket, reasonably well centered. A gentle pressure on the coffee spreads it out in the basket. When paddle-thwacked, the coffee is loaded up on one side and needs moving. A heavy tamp on an uneven distribution results in severe density gradients.
Untrue - on both counts.
While you are correct on what happens when the doser is used as designed - there are three things you skip over.
First - as ambient humidity and temp change, the grind must change - which results in the volume dosed changing. As beans age, the grind must change - again, resulting in the dose changing.
Second - accuracy of dose in a commercial environment is vital. With the variables in play, the "doser" model you describe is unlikely to result in accuracy greater than 0.5g. That's not viable unless you're using coffees that are incredibly forgiving (see Italian blends with high counts of CD Brazils and robusta).
Third - a skilled barista can "paddle thwack" dose to a consistent accuracy of 0.1g and with consistent bedding within the portafilter. This is not opinion - it's simple fact.
cafeIKE wrote:When a basket is overdosed coffee expands to the shower screen. Grind must be coarser to allow water to pass due to the extra screen compression on the puck. If distribution is poor and heavily tamped, the water will force its way through the less dense areas of the puck that are not even more heavily compressed by the shower screen, i.e. channel.
Coffee does not expand within the portafilter until the pressure release valve is triggered. In other words... after the shot is stopped.

The point of updosing certain coffees is actually largely to allow for a coarser grind as this creates a different flavour profile.

Absolutely true that poor distribution will result in uneven extraction. Thus... the importance of the "pretentious" techniques you deride.
cafeIKE wrote:With a proper finely ground dose, the puck may barely touch the shower screen in a small area. As coffee is removed, any resulting pressure is relieved. Only water pressure is controlling the flow through the puck. The puck is more fluid and less likely to channel. This paper on Coffee Percolation is most interesting. It's a bit heavy on the math, but the concepts are reasonably well explained.
1 - "Proper"?!?! That's dogma. Pure and simple.
2 - And, of course, the paper is also dogma. Interesting - but dependent upon a number of assumptions that are largely (as mentioned above) tradition rather than science.
cafeIKE wrote:Which brings us back to :
Dosers are "by volume" devices.
The issue at hand is how repeatedly a given doser volume matches a dose by weight.
Dose volume and weight rarely track well over time in a volume environment. The combination of the ambient environment variables, additional variables (like grinder temp) and changes to the coffees themselves mean that it's best to choose to dose by one or the other and try to be consistent with that one.

It's the consistency to one of the two that really matters.
Most people who make quality coffee at home seem to try for consistency of weight over time.
Most (good) pros seem to try for consistency of volume over time.
This makes perfect sense. In a commercial environment it's simply unrealistic to try and be consistent by weight. And in a home environment, it's hard to get enough practice in to be able to be consistent by volume.
Both produce good results.

Don't believe anyone who tells you that they do things the right way.
Experiment for yourself. Think for yourself.
If it tastes good to you - it is good.
Dogma stops progression.
There is no golden rule.
"Taste is the only morality." -- John Ruskin

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#26: Post by malachi »

RegulatorJohnson wrote:in my esperience (espresso experience) i have found that clumping is related to surface oils on the beans. no surface oil (dry beans) no clumps, slimy, oily beans will give me the clumps every time. some beans start out dry then age and begin to show surface oil. these beans don't clump at first, then they do clump when the oil is present.

that what happens for me. YMMV.

It's one of the common causes.
Static charge is another.
And certain kinds of beans just seem to clump heavily (moisture content perhaps?).
"Taste is the only morality." -- John Ruskin

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cafeIKE (original poster)
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#27: Post by cafeIKE (original poster) »

malachi wrote:Third - a skilled barista can "paddle thwack" dose to a consistent accuracy of 0.1g...
malachi wrote:I have to call full-on bullsh** on this.
:wink: because were it the case shots would be far more consistent than they are. Tell us who can consistently dose to this accuracy and we'll send over someone with a 0.001g balance and a film crew. The instructional video will be worth millions.

Shots in Italy are consistent. Find a good shop and you receive consistently good espresso. Yes, Italian espresso can leave a lot to be desired, but seldom is it undrinkable. I've left as many shots on the bar as I've finished in the rest of the world.

In America, England, Canada, Mexico, [almost any country], you may get a good shot by sheer chance and the likelihood is inversely proportional to the "show". The probability of getting an equally good shot on a repeat visit is below 50%. Some shops and baristas do better than others, but too many baristas learn the "show" before the basics.

I wish I had a tenner for every time I've [sotto voce] "What the F... is that?" I don't give a rat's ass if the barista thinks he's an artiste, 15ml of jet-black tar or 100ml of cafe-au-lait is not espresso.

Over a million air miles have found very few shops, other than an Italian style, where I can consistently walk in day after day, on any shift, and receive a great shot. If the shot is merely good, and close to it's predecessors, the shop is in the extreme minority. I'm not counting *$, or any other place using automatics, as a 'shop.' They are simply caffeine purveyors. :cry:

One may like the BBQ glop foisted on the public as espresso, but that does not make it espresso.
A hamburger made from filet mignon is not steak tartare, no matter how impressively the chef formed and flipped the patty on the grill.

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#28: Post by malachi »

That's your experience.
Don't generalize to assume it's universal. Read "The Black Swan" for one good illustration of why this is a bad idea.

IMHO - the habit of assuming that one's experience is generalizable or in any way represents "reality" is the primary cause for much of the disinformation on this site.

In my career I trained a fair number of baristas.
One of the "tests" in training was always consistent dosing. Get your grinder dialed in. Dose and distribute. Dump onto a digital scale (I used a jeweler's scale). Repeat 10 times. If they couldn't stay within 1/3 of a gram, they were not ready to work the bar. Goal was a consistency of +/- 0.1g. This was for entry level baristas.

Feel free to believe your opinion.
But, as noted above, just because you believe it doesn't make it true.
"Taste is the only morality." -- John Ruskin

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cafeIKE (original poster)
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#29: Post by cafeIKE (original poster) »

The habit of disregarding one's experience and that it represents "reality" is a primary requisite for a "delusional" diagnosis. :wink:

IF my experience was limited to a few shops around my home town, I'd agree it did not represent reality. However, as the missus will attest, we leave no puck untamped. Either we're the unluckiest espressionists or our experience is typical. As we apply more diligence in searching out espresso than we do in finding fine dining and we are an order of magnitude more successful diners, great espresso is as scarce as hen's teeth.

In Good espressos I've had away from home you list but 12 shops. If you visit only these shops when traveling, that is not reality. If you, as I do, search out ALL the shops in the area and the reality is not as I suggest, you should have a list of several hundreds.

It's one thing to dose to 1/3g in practise and quite another in production. I'd be quite surprised if a random sample of any barista's production attained much better than ±0.5g. Perhaps, I'll start to carry around my scale and "Hang on! I don't want to drink it, just weigh it." :roll:

There are two sides to the bar and I'm on the other. The proof is in the cup.

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#30: Post by malachi »

The reason I only listed @12 shops is because there is no way I'd recommend a shop that I've not (personally) had great espresso from. And there just aren't that many such shops in the US.

But your point was that the Italian way of dosing is inherently superior to the "thwacking" style (and that no baristas can be more accurate than a doser as a secondary point).

My point is that, just because 99% of all coffee bars in the US produce espresso that is inferior to what you get in Italy - this does not mean that the Italian way of making espresso is superior to what is practiced in the remaining 1% of US coffee bars.

At this 1% (and I'm being generous claiming such a high percentage IMHO), you are likely to see all the things you deplore (thwacking, grinding per shot, updosing, no robusta blends, etc.). You're also likely to find truly great espresso.

In terms of the accuracy of dosing thing... The test I mention earlier is, as I said, for entry level baristas. Now imaging that same barista (at one of the 1% shops) after 2 years of service. If it's a busy cafe and they're working full-time, this means that they have probably dosed somewhere between 75,000 and 125,000 times. The same technique based on the same training. The same dose, in the same baskets, with the same machines and the same grinders and likely the same coffee... Believe me... you get real consistent.
"Taste is the only morality." -- John Ruskin