Longer pre-infusion for less channeling?

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lassepavoni
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#1: Post by lassepavoni »

Asking for my La Pavoni Europiccola :roll:

Seems that my puck prep is pretty sub-par, so I am trying to weed out the mistakes one by one. Obviously ''being consistent'' isn't something you do up front, but something you learn to master the longer you try. Short of trying everything possible at once, I want to start out and try to fix as many variables as I can from the beginning and work my way slowly through to perfection... or something like that.
I have noticed that about every other shot shows signs of channeling. It starts out okay, slowly dripping at the beginning, but then suddenly starts to run fast and look pretty blonde. Most of those shots tend to be on the acidic side (i.e. not to my liking), while some of them do taste pretty well. Anyhow, this is the sort of inconsistency that I'd like to reduce to a minimum.
Having to start somewhere, I'd like to know whether I am better off using a long pre-infusion to evenly wet the puck, or avoid the PI altogether and directly apply pressure. Obviously my own observations are inconclusive and I have no idea if that is due to the PI or not, so I want to decide to PI-or-not and stick to it, while I work my way through everything else that I may mess up.

Thanks in advance for all your tips and opinions.
Regards, Lasse
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PIXIllate
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#2: Post by PIXIllate »

Using a Levercraft style WDT tool is probably the number one best way to produce a more consistent density puck and therefore less channeling. Saturating the puck quickly and then holding a low pressure to allow the puck to swell is also a good way to promote even density and integrity within the puck but if you don't get the dry grounds in a good state before locking in the portafilter PI isn't going to be magic.

bgnome
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#3: Post by bgnome »

What grinder do you have? Your profile implies you are using a Timemore Chestnut. If it is a C2, it can be a bit tricky to get dialed in, particularly for an LP. Preinfusion helps with channeling, but puck prep is usually the main culprit. A puck screen can also help, different baskets, dosing, etc.

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lassepavoni (original poster)
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#4: Post by lassepavoni (original poster) »

PIXIllate wrote:Using a Levercraft style WDT tool is probably the number one best way to produce a more consistent density puck and therefore less channeling.
Levercraft seems to be shipping from the USA only. What about this one from Coffee Sensor? https://coffee-sensor.com/product/ultra ... s-needles/
Shipping cost from Romania to my island is still prohibitive, but I have ordered there before and was pretty happy with what I received.

bgnome wrote:What grinder do you have? Your profile implies you are using a Timemore Chestnut. If it is a C2, it can be a bit tricky to get dialed in, particularly for an LP. Preinfusion helps with channeling, but puck prep is usually the main culprit. A puck screen can also help, different baskets, dosing, etc.
It is a Chestnut G1 with a modified click plate for 1/3 steps ('22 La Pavoni Europiccola unusable out of the box). Probably not the best or easiest-to-work-with grinder for a Pavoni, but at the moment I am more suspicious of my technique than the grinder. I have it dialed in so far as to straddle a middle ground between gushers and chokers, and I am able to adjust for small changes due to aging of the beans, or when trying a whole new batch of different beans.
Regards, Lasse
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mrgnomer
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#5: Post by mrgnomer »

You can make a WDT with a wine cork and accupunture needles. I got my needles from Amazon.

What roast are you using? The extraction sounds like what I get with a drip light roast. A roast for drip is tough to extract for espresso. I've gone progressively finer with a Ceado E37j and SSP HU burrs and get to a choking point that finishes with a fast extraction. There's not a lot of crema, the pour looks muddy but the taste is fruity bright. I like it.

The roast is an artisan 10 day old Humure Rwanda. The roaster did not mark it as either light or drip but really looks and behaves like one.
Kirk
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lassepavoni (original poster)
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#6: Post by lassepavoni (original poster) »

I am doing WDT already. Started out with a single toothpick, and advanced to a selfmade tool with three sewing needles arranged around a wooden dowel. Might as well be that those needles are still too thick and I am digging trenches instead of distributing the grounds. Will certainly have a look into more refined WDT tools.

In terms of roasting I am firmly on the dark side - more into third crack, rather than into third wave 8) . I like a thick, sirupy, almost mousse-like consistency with a strong taste, that lingers on for the next five minutes on the tongue. I pull the shots with a hot machine and plenty of pressure, ground pretty fine till not far from the choking point. That's why it starts out with a drip rather than a stream.
I am mostly roasting the beans myself on a modified popcorn machine, but also try different roasts that I find interesting; they all have in common that they are 100% robusta :shock: . I can't stand the caffeine, actually, but I found out pretty soon that I totally prefer the taste of robusta over any arabica that I have tried.
Regards, Lasse
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Jeff
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#7: Post by Jeff »

Using anything much over 0.5 mm has potential to make things worse rather than better, at least with medium and lighter roasts. I presently use 0.25 mm. If I wasn't concerned about the filter paper at the bottom, 0.3 or 0.4 mm might work just as well. I am guessing that dark roasts may be even more sensitive. The closer you get to the choking point, it seems the more likely a shot is to channel by finding an easier path to the basket bottom. If finer needles for WDT doesn't improve situation, a longer soak may help preserve puck integrity. As you explore, you may find that the longer contact time needs a shorter duration high-pressure extraction to achieve similar flavors.

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

Just pulled out the micrometer: my needles are 0.9mm thick, so probably too much. I will definitely get myself some finer needles, or a proper WDT tool with 0.4mm needles or even finer, and see if that makes things better. Since I usually only pull some shots at the weekend, this may take some time for me to test out thoroughly.
Regards, Lasse
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baldheadracing
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#9: Post by baldheadracing »

To me, Europiccola implies puck screen if one wants to be consistent. After all, handling the water jet that 'randomly' comes out of the shower screen in that machine was the issue that puck screens were invented to fix. (I use the Coffee-Sensor 0.2mm one, but the original BPlus style works as well. I just wanted the thinner screen to avoid possible headspace issues.)

FWIW, when I got my first Europiccola, it took me about 100 pulls before I was able to match the consistency of a spring lever group machine - and that was with a brew pressure gauge and plotting grouphead temperature and top-of-puck temperature for every shot. (I was going to do a "100 pulls - 100 graphs" post :lol:.)

For pre-infusion in a Europiccola - assuming that you are using the stock pressurestat setting of 0.7bar-0.8bar, pre-infuse until first drips start, and then pull down. Pre-infusion should take less than ten seconds, and closer to five seconds. You can change it up after you get consistent results.

ETA: I always WDT on the Europiccola with a home-made Levercraft-type tool. (My Levercraft WDT tool is upstairs with the spring lever machines.)
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Kaffee Bitte
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#10: Post by Kaffee Bitte »

Wdt is not just about declumping it is also distribution. I find the declump easy. Getting the grinds evenly distributed prior to tamp is the most important part and the hardest to know when you got it.
My homemade wdt tool will end up often leaving some voids or I will not notice that one side has more coffee than the other. And boom channeling or spritzing. I realized I tend to end my distribution to one side so have learned to adjust for it. Also I tend to finger smooth the top of the grinds prior to tamp. This can usually give you an indication that a section has less or a void. Should feel a little return pressure, if your finger feels none that little region is probably light
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