Hello!

While extracting (with a bottomless portafilter) I have spots in the basket, where it seems that no coffee flows through + it "sprays" a bit. No matter how good I prep.
I didn't have this issue in the past (even with less prep), it occures some weeks ago (I already tested it with different coffee).

Any ideas what I am doing wrong?

I recorded a short video - maybe that helps (even though at this angle you can't see the issue too well, but you can see at least one spot where it seems like no water/coffee is flowing through the basket holes)

(LM/VST 15g basket - 14g in 28g out, 7 sec preinfusion + ~23sec extraction)

The quality of the coffee or grind.

You may be reaching the limit of consistency for your grinder at that particular dose size and coffee type. If you get inconsistency or spritzing, try dosing down and grinder finer.

I change coffee pretty frequently on my subscription program. I've run into coffee that requires a coarse grind and does very well, and other coffees that are more fussy and require finer grinding for consistency. In that case, I dose down and grind finer until it works and adjust the beverage output to taste.

Also, factors such as the temperature of the beans when ground can make quite a difference.

Your video actually looks fine to me. Yes, there are some gaps, but that's not necessarily "bad" if your shot tastes good.

nuketopia wrote: Your video actually looks fine to me.

Me too. The way you described the problem I was prepared to see some random jet spray, but it looks like the coffee emerges pretty uniformly across the basket.

To the point on coffee or grind, it might be interesting to see another short vid on your grind, to see if and how much clumping you get. Not sure if you already incorporate "WDT" (stirring the dry grounds), but if not, you might experiment with that.

yeah, the extraction could improve some, but like others said, it's not horrendous and if your shots taste ok, you probably don't need to worry too much. That said...have you removed your shower screen and cleaned your group head recently? Anything that messes with your water flow from the group will also mess with your extraction. Things that always need checking are bean freshness, dose consistency, distribution consistency. WDT might be helpful, as was suggested already. I'd ask how old your burrs are, but I don't think there's a single person who's anywhere close to wearing out the burrs on a Sette, as it hasn't been on the marked long enough for that to happen.

Have you tried using a coffee distribution tool? I think that could help in this case, as I have a sette and after using a distribution tool, it helped the consistency and the results of the extraction.

Thanks for all your replys!
I do use a WDT tool & distributor. I also disassembled and cleaned the group head recently (1 week ago).

Hey.

Change basket to something that doesn't allow you to grind so fine. I had some models of Vst , Ims, Reneka microsieve and now I work with original Kwdw 18 g basket that is similar but not the same to a ims competition 18g.

With Vst because of the increased whole surface you grind finer. And the finer you grind the worst even extraction you will have, specially if the grinder doesn't help. You put the grinder outside its comfort zone.

Use a ims basket, grind coarser with 17-18g, top up the pressure up to Max 7-8bar (not 9+) and try different styles of preinfusion if you can (variations).


The spots that get dry(blonde) modify flow on the naked baskets are spots that compress and the flow doesn't go there anymore and it's forces to exit somewhere, so you end up in a uneven extraction with biterness/harshness/salty taste. This is so subtle that most people don't distinguish that taste, but it's there.

Incomplete PI means some areas in the bottom of the puck are still dry. When pressure is applied the air collapses and the remain dry until water permeates and they spritz.

Extend PI and/or reduce dose and/or grind coarser.

Extended PI asks for even finer grind, so this is not a solution.

I believe the problem is the grind is to fine, and the grinder he is using is not so exceptional with super fine grind.

I can obtain the same ratio in the same total time by using 2 totally different profiles that ask for different grind size but the same weight.

20 sec PI with slow flow (1g/sec free flow) then pull for 30 sec with a decreasing profile. 18g in= 45 g out in 50 sec.
5 sec PI with medium flow (4-5 g/sec)- diminish the flow at minimum (1g/sec) until you have the naked basket filled with coffee on the entire surface, then pull the shot until you hit 45g out the time will be 50sec (Adjust grind to get 50sec).

The shots are very different in taste, the grind coarseness is different and for most people the second extraction will be better (because it favors a inferior grinder).

Extend PI at the current fineness. I did not say grind finer.

I also specifically said coarser. Not "finer".

It may indeed be a grinder quality issue but he can always grind coarser and updose.