Pressure Profiling.

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robkinghorn

Postby robkinghorn » Mar 12, 2019, 7:09 pm

Though I've pulled 13,000 shots with my 1979 Europiccola, I just stumbled on an article about profiling, written in 2015 as I recall, and I have to say, I don't know what the heck he was talking about...lever pressure vs. quality of shot or something or other.
I must still have a lot to learn.
My procedure is:
-weigh beans, approx 14 grams depending on bean
-grind with HG1
-level and tamp
-heat and vent pressure at something less than .5 bar
-when pressure again reaches just below .5 bar, raise lever to just below infusion position
-lock portafilter
-raise lever to preinfuse for 15 seconds
-pull the shot
I'd really like to learn about pressure profiling and how it might improve my shots, which everyone says are great. I'll look it up online, but hoped for some clarity here in the group.

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Chert

Postby Chert » Mar 12, 2019, 7:46 pm

What is your method of pulling the shot? You might already have some experience in adjusting pressure to improve the shot. If you hold constant firm pressure as you extract, flow will usually increase dramatically during the extraction time. If you allow that pressure to cause a rapid blonding flow at the end of the shot, that doesn't taste as well, so many of us back off. Now, if you choose you can buy gear to monitor pressure during the extraction, and check for the taste in the cup of a pressure profile. maybe,10 sec boiler pressure, 10 sec 3 bar, and ramp to 9bar for 10 sec, gradually decline through extraction.

EddyQ

Postby EddyQ » Mar 12, 2019, 10:10 pm

robkinghorn wrote:-raise lever to preinfuse for 15 seconds
-pull the shot


I pretty much follow your process and Chert's (declining pressure). But depending upon the coffee, the low boiler pressure of 0.5bar (mine was at 0.7bar) doesn't wet the coffee thru. I notice by checking the bottom of the basket using a bottomless portafilter. In this case where I need more preinfusion, I pull lightly, maybe increasing pressure to 2bar and get a decent preinfusion. I gently return the lever to the up possition before pulling the shot. I do all this in about 10-20sec. With this technique, I never have issues with low or inconsistant shot volume. And temperatures don't seem to go astray (as I thought they would).

Recently I dialed my pressurestat up to 0.95bar. I have not notices a significant improvement with pre-infusion and still need to do the pull for many coffees. And with the higher pressure, I now have a hotter boiler which makes group head temperature management more difficult.

Oh, I didn't see anything in your process relative to temperature monitoring. If you don't have a group head thermometer, you really should get one. Many use stick on temperature strips. Others, like myself, have fixed on a kitchen digital thermometer. Shot quality is so dependent on group temperature.

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guijan12

Postby guijan12 » Mar 13, 2019, 3:27 am

robkinghorn wrote:My procedure is:
-weigh beans, approx 14 grams depending on bean
-grind with HG1
-level and tamp
-heat and vent pressure at something less than .5 bar
-when pressure again reaches just below .5 bar, raise lever to just below infusion position
-lock portafilter


I have a pre-mill LPP with a heatsink installed around the group head.
And pretty much follow your procedure except for:
-Kinu M47 grinder and
-boiler pressure is 1 bar (I found out this works best for multiple shots with the heatsink installed. Temperature is pretty stable around 94C).
-raise lever and press until I see the first drops hanging from the puck.
-Then I raise the lever again to pre-infuse for 15 seconds
-pull the shot, slowly lowering the pressure on the lever until it is just the weight of my hand resting on it.

But I'm also still learning and searching for the best shots ever..... :D
Regards,

Guido

robkinghorn

Postby robkinghorn » Mar 13, 2019, 7:10 pm

Thank you, all.
For a period of time I did use the stick on temperature strips, until I got comfortable with the temperature vs. boiler pressure.
My machine has the red and white button. If I use just the red button, after about 20 minutes, the pressure gauge stabilized at just about .5 bar. That's when I pull the shots. Guido, you're saying you pull shots at 1.0 bar? That seems extremely hot to me...unless I'm missing something. I'd have to flip the white button to reach that bar.
Guigan12, I just started to pull shots as you describe and am very happy with the results.
Yes, I have been backing off the lever pressure as I'm toward the end of the shot.

I think it was the bar numbers that had me confused in the first place. That was referring to the lever pressure used to pull the shot. So you'd put the machine on a scale to determine that?

Apparently, I've pretty much been doing things right all along. It only took me a couple years to get things dialed in correctly. : )

My 1979 machine is all original, including the unobtanium rubber base. I added the gauge, a one hole steam wand tip and am using a bottomless portafilter. I use coffee from various sources, George Howell, night Kitchen Coffee, Philz, La Colombe, Happy Goat, Ruby, Velez, etc.
Any other recommendations?

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Chert

Postby Chert » Mar 13, 2019, 7:42 pm

I'm talking brew pressure measuring, analog type, thanks to the team at Naked.

Check that link. That would be a fun thing to play with. I have too much stuff and if the espresso tastes great already, you are in the realm of law of diminishing returns.

espressotime

Postby espressotime » Mar 14, 2019, 3:01 am

I started using levers 15 years ago.Tried pulling shots in every different way.Pressureprofiling doesn't work for me.
The only factors I'm able to taste in a shot are type/ freshness of beans and temperature.

animus128

Postby animus128 » replying to espressotime » Mar 14, 2019, 4:38 am

What type of beans are you pulling? For beans more on the medium or dark side I feel liken very simple profiles E61 style get the job done perfectly fine. For light roast however I had great success with stuff like 5 second "no pressure" preinfusion, then 15-20 seconds low pressure preinfusion and then a 40 second pull keeping flow constant (so I guess decling presssure). There the difference to standard profiles is huge!

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guijan12

Postby guijan12 » Mar 14, 2019, 7:12 am

robkinghorn wrote:..... Guido, you're saying you pull shots at 1.0 bar? That seems extremely hot to me...unless I'm missing something. I'd have to flip the white button to reach that bar.
Guigan12, I just started to pull shots as you describe and am very happy with the results.
Yes, I have been backing off the lever pressure as I'm toward the end of the shot.



Hi Rob,

It is hot, though maybe not as much difference as you expect.
At 0.5 bar steam temperature is almost 112 Celsius (233F).
At 1.0 bar it is 120 Celsius (249 F).

I installed the heat sink to prevent overheating, but then it took so long for the group head to reach temperature.
Therefore I slowly increased the pressure, until the temperature is stable at 94 C (201 F).
I need a heating flush for the first shot and can pull 5 shots in a row easily.
And that pretty often happens....

Good to hear you like the results of your technique.
I'm still improving mine. :D
Regards,

Guido

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LBIespresso

Postby LBIespresso » Mar 14, 2019, 10:09 am

animus128 wrote:...and then a 40 second pull keeping flow constant (so I guess decling presssure).


This is exactly what I use to determine the pressure of my pulls. We know that the declining pressure helps keep the flow rate constant. I still wonder if it is the "declining pressure" that makes the shot taste better or is it the declining temp and total time that makes it taste better.
I like coffee. I like coffee people. LMWDP #580