Ditting 807 Lab Sweet observations - Page 4

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mtbizzle

#31: Post by mtbizzle »

coffeeOnTheBrain wrote:Thank you for sharing the graphs. What makes you think of fines migration? Maybe the raise in pressure at the end?
The rise in pressure relative to flow. Some people dont put any stock in the "resistance" line, but take a look at the resistance line on these, and think about the fact that the coffee puck is *losing* solubles (mass).

I can't rule out lots of stuff - user error, bean, just the profile (not decreasing flow enough). I don't know why it has happened, i've just observed it.
"All people by nature desire to know" -Aristotle

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Jeff
Team HB

#32: Post by Jeff »

Rising pressure to maintain relatively constant flow suggests strongly that the "resistance" of the puck/basket system is increasing with time. Similarly, decreasing flow with relatively constant pressure driving extraction would suggest the same. With puck erosion, you'd generally expect resistance to decrease with time, not increase.

"Fines migration" has been discussed as a potential cause for this.

I don't put much stock into reading the fine details of the "resistance line", but this is a long-lasting feature, not a tiny perturbation.

mtbizzle

#33: Post by mtbizzle »

Jeff wrote:
"Fines migration".
Yup that is my hypothesis, I try not to claim knowledge where I'm just making an educated guess though. Prima Rep mentioned 'unusual flow dynamics' so I wonder what exactly they are meaning, if it is the same behavior, if there is some hypothesis they have. Pretty vague description
"All people by nature desire to know" -Aristotle

coffeeOnTheBrain

#34: Post by coffeeOnTheBrain »

How about this idea based on Gagne's idea of flow increases due to less solubles in the water rather then less particles blocking the flow.
The Lab Sweet burrs might grind in a way that the coffee is extracted in 2 phases. One which starts immediately and one phase later causing the "increase in puck resistance" or rather "thicker" coffee, causing higher pressures when flow stays the same.

Maybe different chemicals get extracted in that later phase.
Maybe the Lab Sweet pronounces this effect more than other grinders, if it exists at all.

coffeeOnTheBrain

#35: Post by coffeeOnTheBrain »

mtbizzle wrote:... i've just observed it.
Did you ever stop the extraction before the effect occurred?
Maybe even a side by side taste test. Would be interesting to know what the difference in taste is.

mreloc
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#36: Post by mreloc »

FWIW here's a vid of my extraction on an aligned (marker top and bottom burrs) 807 with maybe 20#'s through it. I roast medium/light- and this is a Colombia/Kenya blend. I don't note any significant pressure climb and the stream comes together pretty well, although a bit wiggly near the end. 17g in/20 seconds.