Extraction pattern, how important is it?

[Abe Carmeli]

Regardless of whether I use a flat or a convex piston, Stockfleth or Schomer distribution, I notice that the first moisture to appear at the bottom of the basket is around the perimeter. From that point it gradually spreads to the center. We are talking about a second or two, not 10 seconds. There is no channeling in the shot, and judging by the beautifully cohesive puck after the knock, the saturation in the puck is even.

Question is - how does that pattern of progression affect the shot? Do you ever get simultaneously even moisture at the bottom of the basket, and if so, have you notice an improvement in the cup?

[PeterG]

I am not the most expert at diffusion patterns.

But it seems to me that, on both my LM and E61, there is a 'dead zone' right in the middle of the dispersion area. Water seems to come out of the dispersion screen in a donut pattern. I guess this is because the water comes out of the dispersion screw sideways. Methinks this is what causes the effect you describe, (which I observe as well)

Given what I posted earlier about tamper shape, one way to fix this might be a concave tamper design; which would compress the outer rim more tightly than the inner zone, perhaps offsetting the donut effect.

In practice, I don't necessarily think this is a huge deal. The outer coffee extracts a couple of seconds longer than the inner coffee, and this may lead to increased complexity in the cup. Be cool to experiment with though, I agree.

Peter

[Abe Carmeli]

Given what I posted earlier about tamper shape, one way to fix this might be a concave tamper design; which would compress the outer rim more tightly than the inner zone, perhaps offsetting the donut effect.

.
I tried a concave tamper as well. Man, it took me an hour to dig that one up. It made no difference. The extraction also starts at the basket out-most circle, and spreads inwards.

[malachi]

As Peter says, it depends on the dispersion method of the machine. If you see that sort of progression with an LM (for example) it is a sign that your distribution is center-weighted. But if your machine's dispersion method is not center-weighted but rather periphery weighted, then it's not a sign of anything per se.

[another_jim]

Baskets themselves tend to become convex with age (unless you tamp them outside the PF like I do). This means the coffee will be deeper at the center, and this may slow down the saturation of the center of the puck.

In any case, I haven't noticed this pattern with my shots. On the other hand, if the dispersion fills up in a second or two; I woudn't have. I'm so used to not watching in the first 10 seconds, when the pump ramps, I hardly ever watch. But on the naked PF, the coffee actually starts to ooze out after about 7 seconds, although it doesn't start dripping until about 10. By that time, it's well distributed.

[DavidMLewis]

Regardless of whether I use a flat or a convex piston, Stockfleth or Schomer distribution, I notice that the first moisture to appear at the bottom of the basket is around the perimeter. From that point it gradually spreads to the center. We are talking about a second or two, not 10 seconds. There is no channeling in the shot, and judging by the beautifully cohesive puck after the knock, the saturation in the puck is even.

Question is - how does that pattern of progression affect the shot? Do you ever get simultaneously even moisture at the bottom of the basket, and if so, have you notice an improvement in the cup?

I had that problem with one of the baskets on my Techno. Turns out, to make the story short, that the basket in question had a more bowed bottom than the others. When I put the basket in question upside down on the counter, put a piece of hardwood on the top, and hit it with a mallet, it made the bottom flat and the extraction then began evenly across the bottom. And yes, it did taste better; that's my story and I'm sticking to it.

Best,
David