Does average pull time include preinfusion?

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d-blank
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#1: Post by d-blank »

Hi all.

I have not aware of the preinfusion till recently, I am in the stage of changing my machine, so I have found some manual one you can control the preinfusion.

as far as I know preinfusion takes anywhere from 5 to 8 sec, but I watched some youtube, shots from the GS3 is actually close to 9 or 10 sec when you see the first drops of espresso.

so, for a shot takes about 25 to 28 sec, does that including the preinfusion time in it? or it should be 25 to 28 plus some 5 to 10 sec for preinfusion to complete the shot?

Thanks

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JmanEspresso
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#2: Post by JmanEspresso »

When I use pre-infusion on my machine, I set it to anywhere from 2-6seconds.. Most often 3 or 4.

40seconds is my general rule of thumb, for the longest Ill let a shot run. On my current setup, in general, shots that run much longer aren't as enjoyable. I do expect the total run time of a shot to be a bit longer, when I use Pre-Infusion, purely because, with or without P/I, I dont want to see any drips until a couple seconds after the pump starts. So if a shot runs 29seconds without any P/I, if I add a 4sec P/I, Ill aim for a 33sec shot.

But, there are exceptions and limitations and situations that will always be different... It all depends on the coffee Im using what I want to do with it.

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another_jim
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#3: Post by another_jim »

It's not an easy question to answer.

First off, I prefer the term "dwell time" for the time from turning on the pump to seeing the first drop. Every manufacturer claims that their particular device for controlling the dwell time is preinfusion, while everyone else's is not. So I get a sinking feeling whenever I hear the word "preinfusion."

A classic E61 can go 10 seconds before one sees the first drop. A group where only the gicleur and head space above the puck to control the dwell time may only have 3 seconds if the basket is over dosed. Moreover, the initial flow, when it does start, can be in drops, or can switch on like a faucet, depending on group, basket, and dose. So how does one account for these variations?

My contention is that there is no taste information to be gained simply from knowing how long a shot went. It is the flow rate of the shot at roughly the middle point, say 15 to 20 seconds after starting the pump, that really tells you whether you are pulling a lungo, normale or ristretto. A person should learn to judge the flow at this point of the shot.

As a rough guide for learning how to judge the flow, I would (hesitantly) propose these numbers:
  • Shot time = Flow time + half the dwell time
  • Standard Double = 27 to 30 seconds, 1.5 ounce volume, 1 ounce weight
  • Ristretto Double = 30 to 35 seconds, 1 ounce volume, 0.5 ounce weight
  • Classic Normale Double= 22 to 27 seconds, 2 ounce volume, 1.5 ounce weight
  • Halve the weight and volume, but keep the times the same, for singles
Jim Schulman

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cannonfodder
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#4: Post by cannonfodder »

Varies by machine/coffee/infusion pressure. The end goal of preinfusion/dwell time is to saturate the puck before the system comes to full pressure. When I had my two group, I had a delay on make timer so I could dial in the time. I would get full saturation of the puck prior to the pump kicking in but not so much that I get droplets forming on the basket. Since your extraction has started during the preinfusion, just at a slow rate, I would factor that into the shot. So it would not be 6 seconds of preinfusion at mains pressure than 28 seconds for a total of two ounces in 34 seconds. It would be more like 31-32 seconds. On my elektra it comes to full pressure almost instantly. I tend to run shorter on the times with it, instead of say 28 seconds, I will go 24-26. Again, times vary by machine/blend/dose/etc...

The easiest thing to do, get yourself some good coffee, a notebook and a stopwatch. Then make notes. What tastes the best for that coffee? That is obviously not factoring in the changes you can make in dose.
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Peppersass
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#5: Post by Peppersass »

another_jim wrote:It is the flow rate of the shot at roughly the middle point, say 15 to 20 seconds after starting the pump, that really tells you whether you are pulling a lungo, normale or ristretto. A person should learn to judge the flow at this point of the shot.

As a rough guide for learning how to judge the flow, I would (hesitantly) propose these numbers:
  • Shot time = Flow time + half the dwell time
Jim, how are you defining "Flow time"? Is it the time from the first drops emerging to the end of the shot?

Also, I don't understand the relationship between the "Shot time" equation and judging the flow rate from the 15-20 second point in the shot.

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another_jim
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#6: Post by another_jim »

Peppersass wrote:Jim, how are you defining "Flow time"? Is it the time from the first drops emerging to the end of the shot?
Yes
Also, I don't understand the relationship between the "Shot time" equation and judging the flow rate from the 15-20 second point in the shot.
Use a timer, and make normale and ristretto shots that fit the rough time frames I gave; then learn how the flow looks for each style. Judge the flow after it's settled in and is running steadily in the middle of the shot. A ristretto is a thin stream just beyond a dribble, while a normale is a thick stream just short of gush. The regular shots are somewhere in between.

These judgments require some experience, and at first you'll need to use a timer as a reference. But I find I get more of a sense of how the shot is doing from watching the flow than from watching time and volume. On the other hand, who doesn't like watching a waterfall? So maybe its just that. :wink:
Jim Schulman

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Peppersass
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#7: Post by Peppersass »

another_jim wrote:I find I get more of a sense of how the shot is doing from watching the flow than from watching time and volume.
Ah. I get it. Thanks. This is really interesting. I don't recall seeing any previous mention of a correlation between observed flow rate at mid-shot and the type of shot being pulled. I've used the flow rate to judge whether a shot is progressing within reasonable bounds (i.e., is going to be a sink shot or not), but haven't realized that this can be taken to another level.

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michaelbenis
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#8: Post by michaelbenis »

I think Jim's reply here is pure gold in directing attention to the pour and not just the time.

In my experience getting the extraction right is about getting a feel for the consistency and flow rate of the cone. Concentrating on that rather than the stopwatches and maths could help many people learn to make a superb espresso....er....faster... :?
LMWDP No. 237

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another_jim
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#9: Post by another_jim »

When I see Barista Championship competitors critiquing shots, they mostly go by flow. Checking the "mousetails" is also part of the old Italian barista lore. This is partly just based on convenience, since it's faster to look at an instantaneous flow. But once you've pulled a few good shots, checking to see that the flow develops in the same way in subsequent shots conveys a lot more information, although qualitative and harder to interpret, than just the time and volume.
Jim Schulman

AidanC
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#10: Post by AidanC »

I have never timed my shots but i prefer the taste of a flow similar to that of a ristretto. I like to use sight and stop my shot either when in blondes or try to cut it short just before the blonding process.

The way i tell that I have had full extraction is when I knock the puck out and I dont see any oil. If I see a little oil i know I could have ran it longer. I aim to see a smidgen of oil residue left in the basket and see no blonding. That is how i tell my shot time is my personal "ideal".

I guess I'm more a touchy feely sorta person, I'm not really into digitizing everything, that makes me go insane.. You could say I'm analogue :)

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