Guys I have this questions that's been annoying me so much.. I understand the concept of weighing espresso from grind size to extraction..

OK what if I have a volumetric machine? Do I need to weigh the extraction if I already weighed the grind?

If I have to stop the machine when it reaches the best extraction ratio that was 'best' for the taste, it means I'll not benefit from the volumetric capabilities of the machine if I have to do that manually each time..

Or does it mean I just weigh the grind and by setting the appropriate water volume, I can skip the extraction weighing process?

From everything I've read, it seems the best practice is to set your volumetric settings to give you the desired weight in the cup, when pulling a shot. This isn't particularly easy, because between the puck and the headspace, there is more water being dispensed through the flow meter than what ends up in the cup. So, if you want a 36g beverage, you need to adjust your volumetric setting to give you say 72g of water and then weigh a beverage using the volumetric button. If you get 46g in the cup, you need to reprogram your volumetric to give you 62g (46g actual - 36g desired equals 10g too much water). Repeat this process until you get close to your desired output weight using the volumetric button.

Once you've done this, you should be able to use the volumetric feature of your machine with some level of accuracy, but not all machines are created equally in this regard. I'd use the scale to verify performance and see if you are satisfied with the output. If you are, I think a weekly check, coupled with an adjustment when changing coffees should keep you in good shape. If your machine is unreliable when using volumetric dosing, I'd stick to weighing output.

Do remember that what matters is not so much how accurate the output in the cup is but how tasty it is. I don't really care if my 18g in is 32 out or 40 out as long as it tastes delicious. If your machine is accurate to +/- 2g, see if your taste buds care before deciding whether or not the variation is acceptable.

Cheers!

- Jake

On a related note on water in the head space, the volumetric dosing on the espresso machine doesn't have any idea the weight of your grinds in the portafilter, or how much water the grinds will retain after extraction. So if you switch beans or roasts, or if you change the weight of your grinds for extraction, the retention of water within the leftover puck may change and this will result in a different weight of espresso in the cup.

Having owned a volumetric machine (La Spaz Vivaldi) for almost 10 years, I see very little value in the volumetric dosing function if you have a scale for extraction. These days, I only use the volumetric function as a safety feature to prevent the machine from going forever and overflowing the cup if I get distracted while pulling a shot. Otherwise, I always stop the shot based on weight in the cup.

Ashk91 wrote:Guys I have this questions that's been annoying me so much.. I understand the concept of weighing espresso from grind size to extraction..

OK what if I have a volumetric machine? Do I need to weigh the extraction if I already weighed the grind?

If I have to stop the machine when it reaches the best extraction ratio that was 'best' for the taste, it means I'll not benefit from the volumetric capabilities of the machine if I have to do that manually each time..

Or does it mean I just weigh the grind and by setting the appropriate water volume, I can skip the extraction weighing process?

I would personally go by extraction ratio, not volumetrics. I had a volumetric machine for years, but once I started overriding it and pulling by ratio, the consistency improved exponentially.

If your process is accurate and repeatable then you can leverage the volumetric function on your espresso machine without problems. But if the beans change or age, or the grind changes, or your tamp is inconsistent, or you have various levels of channeling, then your output volume/weight will be different every time and you won't be happy with the results.

Someone else did some pretty great testing on volumetric vs cutting off the shot yourself by weight and it convinced me that not only is volumetric more convenient it is also much more consistent. My quick search didn't find it though but I'd recommend it. Volumetric was much better at shutting off at the target time but the remarkable thing seemed to be with less than ideal pours where somehow the volumetric made some... adjustment? I don't remember. But I'm all for it!

It sounds best to set your volumetric by actually preparing an espresso as you like it, not just by running the right amount of water through.

I'm a fan!

Edit:
The post I remember analyzed the data a bit more but here is the video, I guess, probably.... Does a Home barista have more ability to concentrate on the shot to cut off at the right time than a busy barista? Maybe, but not me in the mornings!

Why should I care about blonding?

I've been engaged in an ongoing effort to talk myself into "upgrading" my 10+ year old Vivaldi to a LM Mini. But I've been bummed about losing volumetric dosing. I was convinced by Kaminsky's experiment comparing eyeball v volumetric in a commercial setting. Plus, my volumetric Vivaldi is paired with a timer-based K30 grinder, and this means that everyone in my household can pull a competent espresso or americano.

Still, I lust for the elegance (and 58 mm basket) of the Mini. I was in Seattle last month for work, and I spent a happy afternoon at the La Marzocco store pulling four bazillion espressos and cappuccinos on their Mini. They had it paired with a Luna scale, which made me happy b/c it solves the volumetric problem. I bought myself a Luna hoping this would prove a gateway drug towards the Mini.

My shots the last few weeks using the Luna's weighed output have been much better than what I achieved volumetrically. I imagine this reflects variability in beans, weather, puck H20 retention, etc. It is still great to have volumetric dosing for others, and if I'm making an americano I often won't bother with the Luna. But this experience underscored that for this home barista at least:

Eyeball > Volumetric Dosing > Weighed Output

russel wrote:The concerns and priorities of a commercial workflow are vastly different from those of a home barista, but this write up from LM is still worth reading:

http://www.lamarzoccousa.com/blog/ben-k ... lumetrics/

Interesting article. I guess I'll have to keep messing around with my volumetrics. I cannot seem to get any sort of consistency with my grams in and grams out with my volumetrics.

In a busy shop, I think volumetrics is excellent. Here's a video from 2014 that Matt Perger and his team put together testing a Linea AV agaisnt one of their baristas. For home, I use my volumetrics for various size flushes only and use a scale under the cup for shots.