As to Peter, I was just outside thinking about your lack of interest and realized that my interest wouldn't exist if I were completely satisfied with what I'm pulling out of my various espresso machines. I have been searching for my own personal and reproduceable perfect shots now for....6-7 years? I'm a slow learner....:-)))))))))
Susan
Yeah, I get that. Lack of satisfaction is a strong motivator. I'm still somewhat interested, just to get some understanding of the process.
But let me ask this; if you find that 18% is where you want to be in extraction percentage, and you're above or below, what is it that you change in the process to hone in on the 18%? Amount of coffee used? Shot time? I may get hooked into this after all.
Adjust the grind! I can't help but approve of any experiment that smells as bad as the puck bake, but it is really hard to pull it off with any precision. 1% of a puck is less than .2g, which means you would have to filter the shot and add that back into your total, as well as scrounge for all the loose bits on your grouphead.
I think the easiest way to play with it is to filter a shot through paper, and then use about $800 of refractometer and software. Then you jack around with every parameter you can think of. You can make it go down pretty easily. Up is harder.
Or, you could brute force it, and hold the coffee to water ratio constant and adjust the grind.
For example 18g in, 35g in the cup. Maybe you like 60g out, maybe 30g that's all fine too as long as it stays the same. Start with your grinder way coarser than you need, and stop the shot when you hit 35g out, regardless of what the flow looks like. Repeat with tighter grinds, essentially until you choke it.
If you have no big limitations in temp, grinder distribution, distribution, etc. most people will find that the best taste, and good looking flow timing occurs in the 18-22% extraction range. You would need to do this after any changes that would alter the extraction rate. (ex. PID setting, water tests, pressure settings,roast level,coffee,etc.)
The big conicals will show good flow timing across a much wider range than lesser (now being sold) equipment. In some ways that is cool, allows you to flow nice and soft for a wider range of adjustments. In some ways that is bad, making it harder to diagnose shot quality by just looking at the flow. (see how I pulled this back on topic?)
