Dead spots midway through the shot, bitterness

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GurgenPB
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#1: Post by GurgenPB »

Hello

I would appreciate the community's help on this.

I'm fairly new to higher end equipment. Currently have a Slayer SG and Lagom P100. when I work my way down from a coarse grind to a finer one to get an approx. 20-25ec pre-infusion, 25-sec flow on the Slayer with what should be great light roasts, I get dead spots on the PF, and the shots tase bitter/over-extracted. It's obvious from looking at the inverted knocked out puck, that the bottom of the puck is not extracting and is channeling at the very bottom around the dark spots (attached image)

Light Roasts
18g in/36g out (VST 18gram basket)
Slayer SG (94 deg C)
Lagom P100 (700rpm, 0.6-0.7 grind setting, properly zeroed)
meticulous puck prep (RDT, WDT, tap on counter, w/ and without porcu-press, tamp with a Decent self leveling tamper)

Please help,
Thank you
- Gurgen





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spressomon

#2: Post by spressomon »

Try stretching the ratio to 18/36 or even 18/45 by grinding coarser. Seldom do I find 18/26 with your perimeters using a "light" roast...desirable.

Also, how often are you backflushing the machine? How often are you backflushing with cleaner? Condition of the shower screen?
No Espresso = Depresso

GurgenPB (original poster)
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#3: Post by GurgenPB (original poster) »

Thank you very much for your response... that was a bad error: it's 18g in and 36g out (not 26).(sometimes 40)

Original post corrected. I backflush once a week, clean the shower screen, etc about once every 3-4 days. I think I'm as meticulous as it can be. Make about 5 shots per days.

Appreciate the help.

zefkir

#4: Post by zefkir »

You're grinding much too fine. Also PI is not really necessary with a P100, often counter productive even.

More sensible shot parameters would be 18:36 in 22s (counting from pump start) or 18:54 in 20s. It'll change quite a bit depending on the coffee.

GurgenPB (original poster)
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#5: Post by GurgenPB (original poster) »

Thank you. I would love to understand why (the p100 factor).

Thank you for the last point.

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spressomon

#6: Post by spressomon »

Are you getting first drips at 20-seconds or just going to FB at 20-seconds? Have you checked your pre-brew flow rate? Just guessing from the appearance of the first photo, you might have a very low flow rate that is preventing the puck from being saturated and/or just too fine a grind for that bean.

Although generally used for medium-dark and darker roasts, anything is worth trying to try to determine the issue(s): Take PB to 5-6 grams in cup then to FB until you have 22-25g in cup then back to PB until you get 36-40g in cup. Ideally, the total amount of time for the PB-to-FB-back to PB and ending with 36-40grams in the cup should take about 60-seconds +/-. Adjust grind accordingly.

Caveat: I have zero experience with the P100 so maybe defer to @zefkir's above post about same not needing any PB/PI. FWIW/FYI: I am using a 6YO Kafatek Flat with the then stock Mythos burrs. Most of my espresso time is in the medium-light and medium playground. I have found few "light" roasts worthy. Have you tried other beans and/or roast levels?
No Espresso = Depresso

GurgenPB (original poster)
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#7: Post by GurgenPB (original poster) »

Hi @spressomon. Thanks for chiming in again.
Are you getting first drips at 20-seconds or just going to FB at 20-seconds? Have you checked your pre-brew flow rate? Just guessing from the appearance of the first photo, you might have a very low flow rate that is preventing the puck from being saturated and/or just too fine a grind for that bean
I go to FB only after the bottom of the PF is saturated, that happens at about 18-22 seconds. Only then I go to FB. It's dawning on me that I just went for "light roast setting" of 40-45 grams (most recently 40g) in 30 seconds when tuning the needle valve) and didnt think about it much until now.
Although generally used for medium-dark and darker roasts, anything is worth trying to try to determine the issue(s): Take PB to 5-6 grams in cup then to FB until you have 22-25g in cup then back to PB until you get 36-40g in cup. Ideally, the total amount of time for the PB-to-FB-back to PB and ending with 36-40grams in the cup should take about 60-seconds +/-. Adjust grind accordingly.
Didn't know they use this for mostly medium-dark roasts. The video said in general terms that the extended PB is used to lower acidity, didn't know that is mostly for med - dark roasts. Again, I'm just now learning all this. I have tried doing the extended PB to 5 grams, but that had no effect as far as addressing this problem .. I'm not getting a lasting saturation at the bottom, the puck wets and is expelled uniformly in the beginning and the uniformity breaks up immediately and i get spotty extraction.
Caveat: I have zero experience with the P100 so maybe defer to @zefkir's above post about same not needing any PB/PI. FWIW/FYI: I am using a 6YO Kafatek Flat with the then stock Mythos burrs. Most of my espresso time is in the medium-light and medium playground. I have found few "light" roasts worthy. Have you tried other beans and/or roast levels?
Yes I have... and I do gravitate toward medium-light roasts.. But I tried THIS bean and was able to somehow pull a decent shot that was amazing... and i still can't replicate it. Not even sure if you'd consider this light, or medium-light. Again, I'm learning... and always appreciate your and everyone else's help.

I think it's a combination of being too fine and too slow of a PB in this case. I'll work on this... perhaps ill add a video. Thank you again.

GurgenPB (original poster)
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#8: Post by GurgenPB (original poster) »

zefkir wrote:You're grinding much too fine. Also PI is not really necessary with a P100, often counter productive even.

More sensible shot parameters would be 18:36 in 22s (counting from pump start) or 18:54 in 20s. It'll change quite a bit depending on the coffee.
Interesting... so a 1:3 ratio should be pulled faster (coarser grind) to avoid overextraction/bitterness than a 1:2 shot. Makes sense.

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spressomon

#9: Post by spressomon »

To clarify: Sometimes, depending on how a certain bean is behaving/pulling I will use the PB to 5-6grams in the cup then FB to 22-grams in the cup and finish the shot back at PB. Most often, I use this technique (told to me by Nick at Slayer years ago) with medium roast level (City+, Full City) and a little darker to get a sweeter shot.

Whereas, lighter roasts, City+ and City (City is as light as I have used), I'll start with 20-second PB to get first drops...then straight to FB for the majority of the pull...tapering the last few grams/seconds back at PB. Taste and then adjust accordingly.

The most difficult aspect of making really good espresso for everyone but especially novices, is being able to know, from the flavor notes of a given shot, what perimeters to adjust to get to bullseye/2-ring out. To expedite getting to this point, one really should employ the services of a really good barista. That will save you hundreds if not thousands of $$$ in wasted coffee. But, typically, most folks want to put the priority on buying hardware before learning...

There are a number of good teachers on YouTube...Lance Hendrick gets it across very well IMHO.

One last thing: What brew % are you using? And where does the brew pressure top out during the highest psi/bar of the pull?
No Espresso = Depresso

GurgenPB (original poster)
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#10: Post by GurgenPB (original poster) »

Thank you so much for the guidance. Points well taken.

I'll try all of this and keep learning. I still struggle with tasting individual notes and would love to learn more. I have watched ALMOST EVERYTHING on YouTube over the last 2 months on the subject, most better videos more than a handful of times. Would love to find a local barista to teach me but don't even know where to begin to find one.

I realized I didn't Keene as much of the finer points in my years if Breville ownership as I should have. Want as into it then.

Learning now and appraisals your help.