AssafL wrote: Why would coffee be different?

Well, exactly!
If the air between grounds springs back the coffee puck (I was lazy in writing "coffee" or "grinds") then a rather well publicised and/or adopted thought experiment in "maximum compression to prevent channeling" during tamping seems to mean rather less to me.

Ah. Now I get your point.

It is one of those "if I were able to meet my 90's self" I'd tell myself that the problems I had extracting were not related to how Har I tamped but crummy wheezy grinder.

One hypothesis regarding PI is that allowing water to wet the puck and replaces these air pockets with water. Water is incompressible thus allowing flow when the pressure is applied. Without PI the puck would collapse the air pockets and there would be no path for fluid through (as your movies show).

I'm a relative noobie but I've always raised my eyebrow at the "distribution" tools. If you're only affecting the surface it would be incorrect to call it distribution. Grooming is a much better word and I'm glad it's being discussed as such here. If the whole idea is to have as flat and even puck as possible then I can see the point of grooming the surface. The top of the puck being uneven could indeed lead to an uniniform puck. However, I'd say intentionally overfilling a basket and scraping off the excess would be a much more effective way to create and even top than one of the OCD type devices.

I'd also say one of the main reasons to tamp is to normalize the substrate and create uniformity by removing the air and it's rather impossible to evenly distribute coffee into a portafilter before tamping. I.e. you tamp to even the substrate in the portafilter. When loose substrates (at least in my limited understand of the physics of loose particle substrates) are compressed they have a tendency to fill gaps and redistribute themselves, so tamping in essence is a method of grounds distribution. The fact that it is possible to tamp unevenly (lopsided) sort of shows this concept. Otherwise the level of our tamp would be at the whim of the evenness of the coffee in the portafilter before tamping. If tamping were purely for pressure's sake then the simplicity of process provided by pressurized portafilters would be all the rage, yes?

So my opinion is that distribution tools don't do much that an relatively even, eyeballed, distribution of loose grinds into the portafilter and firm tamp won't do. However, the only real way to test the effectiveness of grooming would probably to use weighted grinding and an automatic tamping device. In my own experimentation with different things I've 3d printed and played with the best results seem to come from a simple strike off of the portafilter and immediate and even tamp. I'd even go as far as to say that the tools which limit that error factor of tamping are more valuable than "distribution" tools. Again, this is all anecdotal and opinion.

I tried the needle stirring technique one morning, years ago, and never went back to it. With no other changes in the work flow or coffee the extraction was so much slower than I had been experiencing I never tried it again. I can only theorize as to what the actual casue was, but I think it causes the fines to settle at the bottom of the mass of coffee.

Distribution tools? Not for me.
Distribution TECHNIQUE is another matter.

As a general rule, do what works for you to gain consistency, and thus control over your extractions. But make it as simple as possible. The more steps it takes, the more convoluted the process, the more difficult it is to identify and fix what causes a problem.

And even after all that, there remains only one question.. how did the espresso taste?

Randy G. wrote:I tried the needle stirring technique one morning, years ago, and never went back to it. With no other changes in the work flow or coffee the extraction was so much slower than I had been experiencing I never tried it again. I can only theorize as to what the actual casue was, but I think it causes the fines to settle at the bottom of the mass of coffee.

Randy, I remember your original post, and I will repeat my response: fines migration is pure speculation, and highly unlikely within a dry coffee grinds bed. Slower WDT extractions are almost certainly the result of more even grinds distribution and reduced channeling. The obvious cure for overly slow extraction is to coarsen the grind and/or reduce the dose, not to reintroduce channeling.

Let's try not to perpetuate the fines migration myth, OK? There is absolutely no evidence that this occurs during puck prep. It may occur during extraction, but even that is questionable.

mrjag wrote: 3. Tamp as usual.
4. With the tamper still held at the compressed position, measure the thickness of the tamper protruding above the basket. Subtract this measurement from your total thickness in step one to get your compressed puck measurement.

I was just thinking... after my recent clip which seemed to indicate a reduced recoil after subsequent tamps, perhaps air could slowly dissipate/leak during a held tamp and if it takes a while to measure (after some nerve damage I'm clumsy; it'd take me ages) that might affect the result.
Great idea, still. I'd love to see it implemented.

RapidCoffee wrote:Randy, I remember your original post, and I will repeat my response: fines migration is pure speculation, and highly unlikely within a dry coffee grinds bed. Slower WDT extractions are almost certainly the result of more even grinds distribution and reduced channeling. The obvious cure for overly slow extraction is to coarsen the grind and/or reduce the dose, not to reintroduce channeling.

Let's try not to perpetuate the fines migration myth, OK? There is absolutely no evidence that this occurs during puck prep. It may occur during extraction, but even that is questionable.

First, I said, " I can only theorize..." I have been doing this long enough to be consistent enough in my preparations that if I change just one factor and find such a dramatic difference to hypothesize what it might be. SO maybe a "hypothesize" is instead of "theorize" would have been more important.

Beyond that, if you can say that it is impossible that there were enough fines in the mix, or at least to say, that there could not possibly have been enough small particles in the grind to get into or near the holes in the basket to have caused what I experienced then I won't mention it again.