Channeling?

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Evan

Channeling?

Post by Evan »

Hey guys..first post here. I received my Mini Vivaldi a few weeks ago, and pretty much everything is going smoothly. However I'm concerned about some "holes" in my pucks that occur each time I pull a shot. I know that "puckology" is generally neglected but it's still bothering me.

I dose 16 grams into my bottomless PF. Grinder is a Baratza Preciso. 30lb tamp using an Espro calibrated tamper, and Cafelat tamping stand. After grinding into the PF, I use a toothpick to stir the grounds and break up any clumps. I then give the PF a whack or two on the rubber tamping stand to settle the grounds before tamping.

Shots run 34-37 seconds (including the 6 second pre-infusion) on average for 32g of espresso by weight.

I don't notice any obvious signs of channeling from my bottomless PF, but I don't think my eye is very trained for that anyways.

Any idea what could be causing these holes? They are usually around the bolt imprint.

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Thanks so much!
LDT

Re: Channeling?

Post by LDT »

I was hoping someone would answer this post. I've seen this before but never paid much attention since it didn't seem to affect taste.


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timbo

Re: Channeling?

Post by timbo »

I too have recently picked up an S1 Vivaldi II - the plumbed in one. I have a Mazzer Mini "E" and actually noticed quite a bit of channeling in the first couple of weeks. I moved to the 'toothpick' technique as well - actually I'm using a jeweler's screwdriver, it seems to break up the clumps better, and have had a lot better success since then. I typically do a 'deep' stir of the grounds to fluff them up, and then finish with shallower strokes that level out the basket and break up visible clumps. I tap my pf lightly on the counter to settle the puck, then use a light 'nutating' tamp to seal the edges, followed by the 30lb straight down tamp. I am totally interested in making this ritual more brief - but this level seems necessary to produce consistent shots, so i'll stay with it for now.

I wouldn't worry too much about the pucks after the shot is pulled, when the 3-way valve kicks in, it causes lots of disturbance at the top of the puck, so i'm not so sure that the holes you are seeing mean anything. If you've got a bottomless portafilter, there are a bunch of things to look for:

- pin-hole sprays - these are pretty easy to see - and they make a mess. They are a sign of channeling, which is caused by bad distribution
- gushers - fast blonde extractions caused by coarse grind
- drippers - sludge clinging from the portafilter for 20 seconds is caused by too fine ground
- early blonding - this is when the stream turns blond before any "tiger striping" occurs - i think if everything else is right, this is usually due to the coffee - too old, bad roast, etc

A good extraction, and there are loads of these on youtube, have 8ish seconds of dark dripping from multiple parts of the basket, then, coming together into a single stream for the rest of the shot, with lots of dark and blond 'tiger stripes' for about 15 seconds, ending in a more distinct 'blond' phase, where the shot is normally cut. For 16g of coffee you are looking for 1.5 to 2 oz of espresso.

I find that unless the bottomless portafilter is behaving properly (ie. giving me the show i expect), then there is something wrong with the way i've prepared the basket.

Then again, if it tastes awesome and has that texture that i am looking for, I don't really care what the puck looks like, or what the bottom of the basket looked like during extraction!
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