Posted Wed Mar 21, 2012, 11:42pm Subject: Espresso extraction problem (w/video)
I have been using my La Cimbali M21 Junior DT/1 for about 8 years now with virtually no extraction problems. About 2 months ago I took my machine in for a "tune-up" to Pasquini here in L.A. Ever since I got it back, it has had some extraction problems. I'm not sure if it's the machine or the operator since I totally trust the guys at Pasquini. The major difference is that now my shots are over extracted. I have no idea what went wrong. I am grinding 18 grams of beans to produce a 60ml double through a naked portafilter with the pressurestat set around 1.1 bar. My tamp pressure has been pretty much consistent for the past 8 years. Beans are ground on a Baratza Vario W grinder. If I try and produce 60mls in 25ish seconds I get over-extracted espresso everywhere. Also, I noticed that before I took the machine in, I would get a 6-8 second delay between when I pushed the button for the shot and the time it took for the extraction to start. Now it starts almost immediately.
If I make the grind finer, I can get a nice tiger stripe extraction but the extraction runs into the 40 second time zone with the last 15 seconds or 10-20mls over extracted. So I'll get a good 25 second shot, just not a full extraction. I took a video of one of my "normal" extractions and put it on YouTube. I would appreciate if anyone had any advice as to what I'm doing wrong or what may need adjusting as far as my machine goes. Bean info for video: Intelligentsia "Black Cat" 6 days after roasting.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,763 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Thu Mar 22, 2012, 6:32am Subject: Re: Espresso extraction problem (w/video)
I saw several times that the PF was banged, tapped, etc. Each of these, increases the chances of the puck being disturbed and cracked. The shot showed BAD channeling from the very start, the sprites or sprays of coffee out to the side and not down the center of the main stream are places where you are getting over extraction, if it is happening there, you positively are getting it elsewhere.
The main reasons for thin, weak, over extracted shots are old coffee and chaneling. You may be grinding 18 g of coffee but you are throwing a good bit of it away so you really do not know what dose is actually being used.
The exact mechanics of the preinfusion system on your machine are not something I know about but you might have an issue there. My machine is an E61 (different than yours) and I have about a 5 second preinfusion and pressure ramp up in my shots, if you had a good preinfusion prior to service and do not after, it sounds like something may have happened at the repair shop.
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jwoodyu Senior Member Joined: 31 Dec 2010 Posts: 705 Location: Michigan Expertise: I love coffee
Espresso: Allex Duetto II Grinder: Mazzer Major Roaster: Poppery
Posted Thu Mar 22, 2012, 6:44am Subject: Re: Espresso extraction problem (w/video)
You might be grinding 18 but it looks to me like your scraping a gram or more off to level your basket. I would scale the dose in the basket and the extraction just until you sort it out. It's easier to do if you prep the basket outside of the PF setting the tear on your scale with an empty basket and funnel first. Move the scale to the machine, zero and scale the extraction manually cutting it at couple of grams under 2 times the weight of the weight of the dose. It's easy to nail that down so you can look at the grind etc. Brew pressure is created by the pump and should be right at 9 bar. 1.1 bar is your steam pressure. You could take it back to your shop and have them verify the brew pressure or buy pressure meter online. If your use to getting pre-infusion and you not now that will really change things up on you as well. Your 40 second shot that over extracts at the end if ground a little finer still then pre-infused might pull "pretty" and right at 25 seconds. Is that one those machines if you press and release the brew cycle just starts or if you press and hold the button for 2 seconds then release it does a pre infusion then brews?
Sounds to me like you have a combination of factors working against you not just one problem. I find thats usually the case with difficult issues related to this hobby, computers, women you name it. :-)
You know those people that want to tell you how to raise your kids but have none of their own? That is how i feel when someone with a kitchen appliance tells me how the merits or dis-merits of my machine or how to use it.
Posted Thu Mar 22, 2012, 9:19am Subject: Re: Espresso extraction problem (w/video)
- the coffee looks very lightly roasted - stop twisting the tamper. No gain but possible to disturb the puck. - DO NOT tap the side of the portafilter. No gain, possibility to disrupt the puck. - You may be using too much coffee. Lock the portafilter in, then immediately remove it. Look for signs that the coffee was disturbed by the brewhead. - That extraction looked TERRIBLE. Causes: dosing too much coffee too fine grind too much manipulation when dosing and tamping since the machine has no brew pressure gauge, I suspect that when they serviced it they set the brew pressure too high
Get a scale capable of weighing in 0.1 grams and weigh the dose. That would be a start. On my website www.EspressoMyEspresso.com, check out this article: 12 - EASY GUIDE TO BETTER ESPRESSO AT HOME. It has a LOT of information on diagnosing extraction problems and how to solve them.
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,371 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Thu Mar 22, 2012, 12:34pm Subject: Re: Espresso extraction problem (w/video)
If you have done it the same way for 8 years and everything went to sprites and channeling after service then I agree something (I am thinking pressure too) is set wrong. That is not to say I would not do everything else suggested to you to tighten up your prep. But 8 years of doing it your way should be getting you something like what you got before unless they changed the machine. And in 2 months you have tried different beans I am sure.
Coffeenoobie
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Posted Fri Mar 23, 2012, 11:24pm Subject: Re: Espresso extraction problem (w/video)
Thank you all for your thoughts and advice. The general consensus was that my dose and tamp needed improvement. To frcn: thank you for the link to your guide. I had read bits and pieces here and there but like a typical guy, I don't want to read the instruction manual..."I got this." That was the most comprehensive and complete guide that I have read with regard to espresso prep. So...I practiced today. It wasn't hard. My prep just needed some tweaking. I pulled shots and the more I pulled, the more I came to the conclusion that my problem probably lies in the brew pressure. Thanks again to everyone for pointing me in the right direction with regard to that one. I did some reading on brew pressure and I am fairly confident that is the problem. My shots today came out like this: All were pulled at 60ml/doubles with the same grind setting. The beans were Inteligentsia, Black Cat, and they were roasted 8 days ago. (fcrn: I don't think Black Cat is lightly roasted, could have been the lighting) 1st shot: 18grms extracted in 32 seconds - same type of extraction as in the video, blonde and spraying 2nd shot: 17 grams in 31 seconds - blonde and spraying 3rd shot: 15 grams in 25 seconds - blonde and spraying 4th shot: 14 grams in 19 seconds - blonde and spraying
Notes: interestingly, the 18grm tamp showed just a screw mark and a very light mark from the rim of the dispersion screen when I did the depth check with the portafilter locked in (before the brew). All of the other doses, including the 14 gram one, had some of the grinds sticking to the dispersion screen after I unlocked the portafilter (huh?). Beans were ground in a Baratza Vario W, which is a weight based grinder that weighs within .1 of a gram. The (ceramic) burrs are less than 6 months old. No waste this time with the leveling. If there was any it was only about a tenth of a gram. Also, difficult to dose less than 16grams in the portafilter since the grinds do not evenly reach the basket rim when leveled. I had to do some shaking (sorry frcn).
jwoodyu: To answer your question: My machine is one where you push the button to start and then push it again to stop, unless your using the volumetric settings; then its one push. My machine does not have pre-infusion. The pump pressure ramps up and extracts. That used to take about 6-7 seconds, now it's almost immediate. Im not sure that's pre-infusion. It was my understanding that pre-infusion is about 5 seconds of line pressure to soak the puck followed with pressurized extraction.
Coffeenoobie: Yes I have tried different beans and I think your right on target. I may have not have had the best method of dosing and tamping, but I did get good shots prior to the service.
Thanks again for all of your help. If you have any other suggestions, please post.
Posted Sat Mar 24, 2012, 7:41am Subject: Re: Espresso extraction problem (w/video)
wideawake Said:
1st shot: 18grms extracted in 32 seconds - same type of extraction as in the video, blonde and spraying 2nd shot: 17 grams in 31 seconds - blonde and spraying 3rd shot: 15 grams in 25 seconds - blonde and spraying 4th shot: 14 grams in 19 seconds - blonde and spraying
The first thing to fix is the "blonde and spraying" not the time or dose IMHO (and probably not brew pressure either). Blonde and spraying means that there is lots of channeling which is usually due to not grinding fine enough and/or poor distribution. 9 bars is a lot of pressure - but so is 8 bars as well and usually these are issues with the puck and not the pump. That's why I (and others) feel that tamping pressure is probably not a huge variable in the face of 9 bars of water coming at the puck - recently some of my best shots are with a very light tamp (if the dose and grind are right)
Prior to getting it serviced was there spraying or were you getting nice tiger-striped extractions?
I'd recommend grinding finer until you choke the machine and then back off from there. For distribution issues I'd recommend the Weiss Distribution Technique if you want to experiment.
Posted Sat Mar 24, 2012, 10:15am Subject: Re: Espresso extraction problem (w/video)
clumeng Said:
The first thing to fix is the "blonde and spraying" not the time or dose IMHO (and probably not brew pressure either). Blonde and spraying means that there is lots of channeling which is usually due to not grinding fine enough and/or poor distribution. 9 bars is a lot of pressure - but so is 8 bars as well and usually these are issues with the puck and not the pump. That's why I (and others) feel that tamping pressure is probably not a huge variable in the face of 9 bars of water coming at the puck - recently some of my best shots are with a very light tamp (if the dose and grind are right)
Prior to getting it serviced was there spraying or were you getting nice tiger-striped extractions?
I'd recommend grinding finer until you choke the machine and then back off from there. For distribution issues I'd recommend the Weiss Distribution Technique if you want to experiment.
Thanks for the thoughts cbear9494. Grind was the first thing I adjusted because all of my previous shots were never like this. Yes, before the service, I was getting nice tiger striped extractions. To try and correct, I adjusted the grind down and it would give me a nice tiger striping, but my shots would run into the 46 secondish area, with the last 20mls being over extracted. Any finer, and the extraction gets really looooong. So as for now, I'm drinking 40-45ml "doubles" by taking away the cup and letting the last 15-20mls run into the drip pan. I would like to get it to where I had it; about 60mls and starting to blonde around 55mls. I'm feeling pretty confident in my dose/tamp technique right now since I corrected it and don't think that is the problem. I'm doing it pretty much text book as it relates to frcn's blog about Easy Guide to Better Espresso at Home. It was my understanding that the WDT was to correct clumped, ground beans. My Baratza does not clump so I don't use that technique. Having said that though...don't think I didn't try it a few times to see if that was the problem. It wasn't.
Posted Sat Mar 24, 2012, 2:02pm Subject: Re: Espresso extraction problem (w/video)
wideawake Said:
If I make the grind finer, I can get a nice tiger stripe extraction but the extraction runs into the 40 second time zone with the last 15 seconds or 10-20mls over extracted. So I'll get a good 25 second shot, just not a full extraction.
Frequently, I run shots that take 50+ seconds and are not Over-extracted. What I think is happening is three things: Your machine has an ascending temperature profile. (Temp rises during the extraction, burning the last 20mls). Secondly, there is a delay between you locking in the PF and starting the shot. (This increases the beginning shot temp) Thirdly, you're dosing very low. You're grinding 18G but only 15 is making it to the extraction due to prep rituals.
What basket is that? (Looks tiny)
These are the steps I would take, in order:
Develop a consistent dosing method (weighing, timed grinding, etc.)
Eliminate extra prep rituals (leveling, twisting, tamper tapping)
Grind finer/increase dose
Increase basket size to add headspace (stop throwing away part of your dose in the sink)
Lower p-stat setting to decrease group temps at the end of a long extraction
Try slowly lowering the pressure of the rotary pump. (It doesn't have to be exact, we are brewing coffee, not doing surgery.)
And finally, if that doesn't take care of it, a full grinder tear down.
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