another_jim wrote: {Rant mode on} The normal technique to compensate for staling is to grind finer with the same volume. Thus you use less coffee, and extract more weak tasting, heavy compounds in a coffee whose taste amplitude is already declining. In effect, this is like turning down the volume when the music is too quiet. So it's no wonder that people find too fresh or too stale coffee "undrinkable;" they keep turning up the volume when it's too loud, and turning it down when it's too soft. {Rant mode off}

Good point.
The better solution for (many) staling coffees has always seemed to be coarser grind, higher dose.

While I have always been a dose by volume guy willing to settle for inconsistency, Jim's argument makes perfect sense. I fall back on my various manufacturing jobs from time to time when certain aspects make perfect sense in the espresso world.

In this case, when I worked in chemical manufacturing, my job was to make batches of cleaners, lubricants, coolants, and various quenching fluids, among other products. EVERY ingredient was added by weight, both solids and liquids alike. Even in batches upwards of 10,000 gallons, if you needed a pound, or 40,000 pounds, it was weighed either on a scale or, for the liquids already in storage tanks, with pumps that had built-in mass flow meters. And when samples were taken to the lab, the techs didn't add milliliters of reagent, they also did everything on scales.

So Jim's argument that if you want consistency, look at your weight, is probably the most effective way to eliminate poor shots when all other things are equal. That being said, buy a scale that can be recalibrated, as they do in fact lose their reference as they are used. All of our scales at the plant were tested 3 times a year. Mind you, that when you are making batches that cost upwards of $200 a gallon, you don't want to screw something up, but the logic still applies to the home user.

another_jim wrote: both higher weights and coarser settings for staler coffees to prop up the declining taste.

It is my experience as well.

malachi wrote:2 - different combinations of dose and particle size result in different flavour profiles for a specific coffee. Experimenting with these variables can be revelatory.

That's very much my experience too, and that's discussion I wanted to drag in Jim's previous post but it went dead. Because in busy cafes environment, if the taste is expected to be consistent, one would have to use specially optimized blend in this regard. But I doubt it is this way and honestly I doubt the mentioned inconsistency of the busy cafes. That's why I wanted more discussion there because it is interesting, no?

malachi wrote: 3 - specific (edge case) environments present significant challenges. Working in SF or PDX or Chicago is one thing. Working somewhere with 50+ degree swings day to night, extremes in low humidity or humidity swings

And that is my experience also. The grind setting is stable unless the environment is stable; in other words if weather changes, grind setting change is needed. I was surprised Jim didn't mention that in his first post in this thread.

p.s.
I single dose and weight my doses.

My own experience squares with what Jim is saying except when it comes to humidity. I always dosed by weight on the SJ and here in good old England where you can get several dry days followed by several wet days, it could be necessary to adjust the grind for the same weight if on the same batch of beans.

Another exception can be coffee aging which is quite possibly very much the same thing. This is not a problem for me generally because I buy fresh-roast 250 g bags which I and my new companion get through in a couple of days. Generally speaking even on the dose-by-grind-time Ninos I do not need to make any adjustments once a bean is dialed in - even for humidity because I will get through a bag before it can really have much effect.

Hi guys,

just a note:

It's roughly 0.067 grams per bean, a granularity fine enough to allow very accurate dosing.

Roughly and very accurate don't go together well. Just checked two SO's I'm currently using, one has fairly big beans, the other has rather small beans, average bean weights are below:

20 beans of SO1: 4.40g => avrg. 0.22g per bean
20 beans of SO2: 2.07g => avrg. 0.1035g per bean

Of course the above is only average values, start adding more beans and the error can change by quite a lot. Sure you might end up with some nice accurate values when the errors summed up give a zero, but you can have rather big final errors as well. Of course blends are a totally different animal, as you have a mixture of beans and unknown mixing ratios for a given portion.

On the expense in general -- 1000 gram max/ 0.1 gram resolution scales cost $10 on Ebay

True, 0.1g resolution, but what about total accuracy, ability to hold that accuracy etc? Have a look at laboratory scales and their prices. That is of course if you want accuracy.

Regards,
dsc.

True, 0.1g resolution, but what about total accuracy, ability to hold that accuracy etc?

The $10 ebay scales are surprisingly good. I bought a pair of $10 ebay scales a year ago. A 1000g/0.1g model & a 300g/0.01g one. The 300g scale in particular sees daily use & has sometimes been handled roughly and remains dead accurate a year later. I have a proper calibration weight set (10, 100mg & 1, 10, 100, 300g) to check this as well as a real lab scale (10g/0.001g) that does not get much use due to it's large size and settling time.

No doubt lab scales are better built & more durable. But the ebay scales seem more than adequate for the task, not to mention bargains. The one potential drawback that I see with the ebay scales is that they aren't properly temperature compensated. The scales I have work like champs as long as the ambient temperature is below 30C. And are a bit wonky above that. Not an issue though unless you live in a hot locale & don't believe in air conditioning.

Not that my opinion matters much but since I made two changes, the consistency of my espresso has improved markedly. First I replaced my 8 year old Mini with a Robur E and I also started weighing my shot daily, only adjusting the timer on the grinder and not adjusting the grind (unless I changed beans). I think you could get a grinder like a Robur E to do what Jim proposes with hourly weighing only.

another_jim wrote:You need to change grind as the beans stale, because they become less dense, and you use less weight for the same volume. No change is needed to compensate for staling when dosing by weight.

I was discussing this thread with a local barista of the commercial variety today, and there's a point we don't understand.

Suppose our hapless barista always doses by volume, and is working a shift during which the humidity of the cafe rises. He notices that his flow rate has slowed down. If I understand the thread (and analogues of the quoted text above) correctly, this is because the density of the coffee has gone up, so his volume-based dosing gives greater mass, so slows the flow.

According to Jim's suggestion, if he dosed by mass instead, he would get the same flow. But surely the same mass of denser coffee, made so by moisture, now contains less "actual coffee" --- some of what we have there is additional moisture.

So our question: do we expect the taste to be consistent during such humidity changes, if we dose by mass and keep the grind the same? If so, why? We're changing the amount of coffee in the puck --- not its mass, but the mass of the "actual coffee". Does the yield magically change to compensate?

On the other hand, if the taste is going to change despite consistent flow rate, surely it's perfectly reasonable for our barista to re-dial his coffee, to get the shot to be as good as it was when he dialled it in in the morning?

I don't know what happens with large humidity and temperature changes, if for instance you are working outdoors.

The idea of "false density" caused by water absorption is very acute; I never thought of it or considered it. Thinking about it now, it seems almost like a catch 22. If you grind for each shot, there isn't much time to absorb water, so you don't need to change grind setting. If you fill the doser, the coffee can change density due to water absorption, but it's too late to change the grind.

Two thoughts: Is their a catch 22 smiley? Do Italian or other filled doser baristas tweak the doser adjustment knob, rather than the grind adjustment, to compensate for flow changes?

interesting thread