I've read a gazillion resources about pulling double shots -- in a confusing mixture of metric and American volumes (ml/oz). But here's the crux:

What is the volume -- and the extraction time -- for a double shot?!

I've read 2.0-2.5 oz in 20-25 secs, and a similar volume in 25-30 seconds, -- and various other volumes/times. What does the "ISO ESPRESSO" standard say? I can use Google (and my calculator) to convert from ounces to milliliters (or vice versa), but what is the target, and what is the time?

Thanks to the generosity of fellow HB member Jeff Sawdy (who went out of his way to purchase and send me a mini measuring cup) I'm in a position to calibrate my grind, dose, tamp, machine, etc. to deliver an optimal shot.

What the *heck* is "optimal?" That's my quandary. I've got a copy of "extractionratios-2.png" but there's no mention of extraction *times* there. Is it 20-25 seconds, or 25-30 seconds? Or (more widely) 20-30 seconds? Beyond my own tastes, what is the target zone? What do you use?

That's it in a nutshell (or "nut's-hell" as I prefer to call it).
t++

tmaynard wrote:Is it 20-25 seconds, or 25-30 seconds? Or (more widely) 20-30 seconds?

Yes, it is.

Jim

jggall01 wrote:Yes, it is.

Jim

Well, that's helpful! I'm guessing that you really mean that somewhere between 20-30 seconds is the "sweet spot" and finding the extraction time that suits my taste is the number I need to lock onto (my "bogie" as it were).

Or did you mean that 20-25 was right, or 25-30 was better, or 25.675 is "optimum?"

t++

tmaynard wrote:Or did you mean that 20-25 was right, or 25-30 was better, or 25.675 is "optimum?"

I would say put away the timer and taste the espresso, then you be the judge. For longer answers, see Timing of pull starts when? and Al's Rule.

Tom-

I think the answer is... it's all good if it tastes good to you.

Anything less than 20 seconds is too fast, 25-30 likely better, but I've pulled a number of fine shots at 40 seconds (but not most). Blonding, pour color, consistency might be the better stop factors, not volume.

Depending on personal tastes, beans, crema production, you might find that as little as 1 oz for a double is acceptable... many folks here pull 1.0 - 1.5 oz doubles.

The PNG file you refer to is from AndyS's brew ratio thread, and that is a pretty interesting way to determine what sort of shot you are pulling.... I'm finding the bulk of my current shots on Silvia in the 50% brew ratio range... Weight (while cumbersome) might be a better way to evaluate shots because the "shot density" varies from bean to bean, shot to shot with crema production. My current shots are all less than 2 ounces.

tmaynard wrote:Well, that's helpful! I'm guessing that you really mean that somewhere between 20-30 seconds is the "sweet spot" and finding the extraction time that suits my taste is the number I need to lock onto (my "bogie" as it were).

Or did you mean that 20-25 was right, or 25-30 was better, or 25.675 is "optimum?"

t++

Sorry to make light of such a serious subject (that's me I'm describing, BTW).

These are the (current) rules on my home court:

1. Judge the grind based on the appearance of the espresso stream. If the grind is too coarse, then the stream is big and gushy. If the grind is too fine, the stream ain't a stream, but just little driplets instead. Syrupy and viscous, but not quite breaking up into drops, is just right for me.

2. Stop the extraction when the stream gets too blond. For me, too blond is when there are no more streaks of color. Whatever volume you got is what you got.

3. Shot time = however long this all took.

When it is all working right, and the beans are fresh, I usually get a little more than 2 oz from 17g of ground coffee, and it takes around 25 seconds. I can't remember any good shots that went faster than 20 seconds, but I have had some good ones that went longer than 30. I think that maybe the shot time is secondary to flow and color.

Jim

tmaynard wrote:I've read a gazillion resources about pulling double shots -- in a confusing mixture of metric and American volumes (ml/oz). But here's the crux:

What is the volume -- and the extraction time -- for a double shot?!

To try and keep it as simple as possible, in a double shot aim for:

25 seconds & 2oz (60ml).....20 seconds is too short, 30+ seconds is too long.

You should then vary this volume/time, by altering the grind coarser or finer, tamping, if done reasonably well should not have a significant effect on shot volume (unless it channels badly), but may affect when blonding begins.

The volume is measured using WBC rules as the volume of liquid and crema, but in a "normal" environment, this type of strict measurement rule is not so useful, as the amount of crema could vary hugely. But if your crema settles out to around 8 mm then try to have the 2oz line around the top or midpoint of the crema.

This method will allow you to diagnose problems, as in all cases the shot should be stopped when it blondes. So even if you extract 2 oz in 25 seconds, if it blonded at 20 seconds (and somewhat less volume) you should have killed the shot and then looked for the cause of early blonding.

DaveC wrote:25 seconds & 2oz (60ml).....20 seconds is too short, 30+ seconds is too long.

Not necessarily, I find it depend on the machine. If you happen to run a long preinfusion then the time stretches out vs. no preinfusion. On my Isomac I tend to run 2oz in 26-27 seconds as a general midpoint, it takes 3-4 seconds for the pump to hit full pressure. However, the time varies by blend, some go longer, some go shorter. On my Faema, which has a 5 second preinfuse with 3 bar mains pressure, I run more like 30-31 seconds on a 2oz shot. Again, time varies by blend, some work better with a longer extraction, others work better short. That also holds true for volume. Not all blends are at their best with 2oz extracts. Time also varies based on extraction volume, ristretto shots go longer for a smaller volume.

In the end, you have to decide what tastes best for you. Try keeping notes at the beginning. Try blend X with a 2oz extraction but bracket the time, try 22, 25, and 28 seconds. Taste each, make a note, decide which tasted best and go with that. The same technique works well for dose and extraction volume as well. Then when you hit the sweet spot for a particular coffee, you can reference back to your notes for the proper time/dose/volume. Over time, you will drift away from note taking (at least I did) and the process will get easier. This just helps keep tabs on all the different variables until you become comfortable with the machine.

HB wrote:I would say put away the timer and taste the espresso, then you be the judge. For longer answers, see Timing of pull starts when? and Al's Rule.

I like the timer as a tool for determining what micro adjustments to make, if any, to the grinder, for a better shot the next time.

tmaynard wrote:What is the volume -- and the extraction time -- for a double shot?!

An oft-quoted statement from the Italian Espresso National Institute defines a single espresso as 7g in 25sec producing 25ml (including crema), so a traditional double would be 14g in 25sec producing 50ml (1.7oz). In this instance I believe the Italians have it right.

However, blends and machines and filter basket volumes vary. My approach is to stop an extraction when it blonds, adjusting the grind to achieve a pour time of 25-30sec (a bit longer for ristrettos). When I do this, my resulting volumes are in pretty close agreement with AndyS's chart.

For a more-or-less traditional double, I aim for 45-60ml (1.5-2oz), including crema (which comprises 80-90% of my pours). It's rare that I can extract more than 2.5oz from a double basket without blonding. Some have claimed 3oz as the standard, but that falls outside my range of extraction abilities.
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John