Uneven extraction

Beginner and pro baristas share tips and tricks.
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#1: Post by shadowfax »

(split from The Denver Effect by moderator...)

I wonder something.... the dark spots I am getting, I noticed, always seem to be on the side where i get the slower extraction. I can't seem to get a perfectly even extraction.

these are reasonably typical of my extractions right now:
Monday morning's shot:
Which turned into this:
This evening's:
Which turned into this:

Monday's kinda sucked. It was brewed a little hotter (5 oz flush; this evening was closer to 7oz.), but I feel like the worst of it was how unevenly it started out. Granted, they both started out unevenly, but Monday's was much worse... at any rate, they both have the dark spots on the side where you see the darker extraction.

What do you think, Chris? I suppose I should really be perfecting my distribution before I go looking for other culprits for mediocre shots, huh?

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#2: Post by malachi »

you've got uneven density in the basket.
"Taste is the only morality." -- John Ruskin

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shadowfax (original poster)

#3: Post by shadowfax (original poster) »

well, that seems obvious enough to be a tautology. I know I do, and I am having the darnedest time getting my distribution right. I've read the different methods, and used to have a lot of luck with Stockfleth's on Silvia, but it doesn't seem to work right for me anymore. Maybe I am just way out of practice. It took me almost a month to get good on Silvia, and I have had a month break from doing anything coffee related, so this is basically the start of week 2 of being a newbie all over again. the concepts are fairly solid for me, it's just... not having experience with them, I guess. I have known my distribution is off since I got the machine, and I have been, again, focusing my efforts on and racking my brain about that in addition to wondering about all this flushing and boiling points and all... I guess I'll just keep plugging away.


#4: Post by buzzword »

Newbie for the first time :-(

You can't see below the level surface; density is hidden; method or feel for density are the only things that can create even distribution.

The natural thing would be to say, for whatever reason, you've got more packed (so per malachi distributed) at around 1:30 o'clock, so add coffee at around 7:00 until the problem moves somewhere else.

malachi is like an oracle; his attention to the immediate is like a beacon shining brightly from the direction of excellence, but between me and the light is terra incognita (a Nabokov story title).

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#5: Post by Teme »

I have tried different methods for the distribution and tamping. I have noted that these have helped me eliminate the problem you describe:
  • - When dosing and the basket is 3/4 full, I tap it on the tamping mat vertically a couple of times to aid distribution. I then finish the dosing, level (no pressure, but making sure its even) and tamp.

    - When tamping, I try and avoid tapping the PF to drop the ground coffee from the sides of the PF to avoid channeling. I'd rather have some ground coffee left on the sides of the basket. If there's too much of it I'll tap, but just once.

    - Even, consistent and strong enough pressure when tamping (I tamp at approx. 15kg / 33 lb). I've noted a big difference here and my first tamp is as hard as the final tamp. I ease the pressure for the polish. If my tamp is lighter, I usually get similar results to yours (at least to some extent) and/or random sprays of coffee.

    - Related to the previous one - initially I sometimes unintentionally tilted the tamper when tamping. The puck was higher on one side than the other. I practiced to eliminate this. By extending the index finger and thumb after the tamp, and then turning the tamper to polish, with the extended fingers you feel if the there is a "wobble" that would indicate a "tilted" tamp. I now have the hang of it, but occasionally I do check, just to make sure...
There might also be differences between baskets. For some reason, I find the LM ridgeless double good in terms of my results.

I am also a relative newbie, definitely one in this company, and therefore also interested in further comments...


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shadowfax (original poster)

#6: Post by shadowfax (original poster) »

Teme, thanks, those are very good suggestions. I already do a few of them, like checking that the tamp was level. I've always avoided tapping, even straight vertical tapping. Maybe I'll give that a shot.

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#7: Post by malachi »


Now that is a scary idea.

Given that you see light density near the handle, I'd look at your dosing (make sure you're not front-loading the dose) and your distribution (you might be "working around" the handle when distributing).
"Taste is the only morality." -- John Ruskin

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#8: Post by buzzword »

! speaks :)

This is a great site.


#9: Post by Dripp »

I too have had issues for 6-8 weeks with uneven extraction. Most of the shots were ok, and rarely were they great. My best shots were decaf in the evenings. My issues were always on the right side with overextraction, with the left side being good or underextracted. In another thread, it recommended I read, or re-read as the case may be, "perfecting the naked extraction." And there, in the hall of shame, was a picture of my shots of late staring me in the face. It seems that in my efforts to cure my underextraction, I have been over filling the basket or tamping too lightly, and when inserting the portafilter, I have been slicing the top of the puck. Now I can't wait to get up and try this out.

Admittedly, I don't have a scale for the grounds or the tamp which could help me solve my woes.


#10: Post by tweeek »

malachi wrote:Given that you see light density near the handle, I'd look at your dosing (make sure you're not front-loading the dose) and your distribution (you might be "working around" the handle when distributing).
I've changed machines and got a naked PF in the last two weeks and until yesterday was seeing consistently uneven extractions. I was regularly seeing a light patch at the front (12 oclock, with 6 at the handle) of the basket. Then after reading this thread, I started to think about where the grinds were going when coming out the grinder spout.

Since that epiphany, the pours are starting to even out.