Posted Fri Mar 1, 2013, 12:55am Subject: Temperature Affecting Channeling
Does anyone know how temperature affects channeling or the overall quality of the shot?
I recently got a bottomless portafilter and all of my shots were flowing horribly. No matter whati tried, they were gushing out and spraying all over. My efforts to fix it were unsuccessful. Finally, today, after spending some time on the phone with Baratza (Baratza's customer service is the best.), thinking that my burrs were dull and causing the problem, the guy on the phone suggested that I raise the temperature. So I raised the temp on my CC1 from 202 to 205 and voila! Keeping my shot prep the same, all of a sudden the channeling was all but gone, the tiger striping was there, the shots were flowing well. I didn't realize changing the temp would make such a difference nor have I read that anywhere.
fwtechwiz Senior Member Joined: 19 Feb 2010 Posts: 522 Location: Fort Wayne, IN Expertise: I live coffee
Espresso: Gaggia Evolution Grinder: Hario Skerton
Posted Fri Mar 1, 2013, 2:12am Subject: Re: Temperature Affecting Channeling
If I get lazy and don't wait for a full warmup, or don't temp surf high enough I get more spritzers too. I think it's because the lower temps don't allow the water to infuse into the coffee well and it passes through (point of least resistance). But I think it's just showing out a deeper problem with grind consistency or distribution. Age of the beans have a lot to do with it too. Old coffee will spritz and channel something awful no matter what the temp.
emradguy Senior Member Joined: 31 Mar 2011 Posts: 1,722 Location: Houston Expertise: I live coffee
Espresso: Izzo Alex Duetto II Grinder: MacapM4T, Macap M4, OE Lido,... Drip: Espro press; Aeropress Roaster: internet
Posted Mon Mar 4, 2013, 9:57pm Subject: Re: Temperature Affecting Channeling
As an extreme example. A long time ago, the other "barista" in my house let the boiler go dry on a Silvia, which triggered the safety power cut to the boiler. Before I realized this, I was wondering why the heck the water was just pouring through the shots like the basket was empty (except for the color change). After a few attempts I realized the machine was cold (as in...room temp). I opened her up, reset the boiler, and everything went back to normal (except I was really pissed off).
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,017 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Thu Mar 7, 2013, 5:47am Subject: Re: Temperature Affecting Channeling
This has been a big topic lately so I wanted to check it out. I only did two tests but the results made me not think I had to check it out any further. I tested a cold PF vs a preheated PF on machine with same dose and grind, results where an extraction time with a 1 sec difference ( shot prep easily accounts for this). I then later pulled a shot on a cold machine, brew boiler was around 112f, I got a 25 sec pull, one hour later when machine was warmed and PF preheated I got a 25sec pull with same dose and grind.
I have never had an issue pulling shots with stale coffee and neither do 95% of the coffee house out there. The more comfortable I have become brewing espresso over the years the more I believe shot inconsistencies are created in shot prep. Spritzers are something I have thought long and hard about, they bother the crap out of me and are no fun when doing full nude extractions and I don't mean the PF. I started to think about putting a thumb over the end of the hose, as the flow from the hose gets partially blocked water spritzer every direction, I have wondered if this what is happening at the holes of the basket, a piece of grind is partially clogging one or more holes to make a spritzer. After hundreds of delicious spritzer shots that are consistent flows and tasty I do not consider spritzer's a defect rather a large annoyance.
brianl Senior Member Joined: 1 Dec 2012 Posts: 152 Location: Chicago IL Expertise: I love coffee
Espresso: Gaggia Classic (w/PID) Grinder: Baratza Vario Drip: chemex
Posted Thu Mar 7, 2013, 1:25pm Subject: Re: Temperature Affecting Channeling
germantownrob Said:
Spritzers are something I have thought long and hard about, they bother the crap out of me and are no fun when doing full nude extractions and I don't mean the PF.
Jmanespresso Senior Member Joined: 18 Jan 2009 Posts: 2,108 Location: Westchester NY Expertise: I live coffee
Espresso: Alex Duetto II Grinder: Compak K10 - Vario Vac Pot: Yama-SY5/SY8/TCA5 Drip: V60, Beehouse, CCD Roaster: Hottop B
Posted Thu Mar 7, 2013, 3:10pm Subject: Re: Temperature Affecting Channeling
germantownrob Said:
This has been a big topic lately so I wanted to check it out. I only did two tests but the results made me not think I had to check it out any further. I tested a cold PF vs a preheated PF on machine with same dose and grind, results where an extraction time with a 1 sec difference ( shot prep easily accounts for this). I then later pulled a shot on a cold machine, brew boiler was around 112f, I got a 25 sec pull, one hour later when machine was warmed and PF preheated I got a 25sec pull with same dose and grind.
I have never had an issue pulling shots with stale coffee and neither do 95% of the coffee house out there. The more comfortable I have become brewing espresso over the years the more I believe shot inconsistencies are created in shot prep. Spritzers are something I have thought long and hard about, they bother the crap out of me and are no fun when doing full nude extractions and I don't mean the PF. I started to think about putting a thumb over the end of the hose, as the flow from the hose gets partially blocked water spritzer every direction, I have wondered if this what is happening at the holes of the basket, a piece of grind is partially clogging one or more holes to make a spritzer. After hundreds of delicious spritzer shots that are consistent flows and tasty I do not consider spritzer's a defect rather a large annoyance.
The part I want to highlight here, is that spritzers, or whatever we want to call them, do not mean the shot is off, defected, worthy of throwing away, or bad in any particular way.
I have long believed this to be true. I have pulled plenty of properly flowing shots with no apparent channeling, except my machine, or my face, is being misted with hot espresso(AWESOME.), and Im thinking to myself, what the hell? But the taste is on point, and if I hadn't seen the spritzer, I would have assumed it was a right on shot.
So, while spritzers do often accompany channeling and bad shots, channeling and bad shots don't always accompany spritzers. Ya dig?
Follow Your Bliss
Coffee makes your constantly overcome your prejudices and re-evaluate your own "received wisdoms" when it comes to judging cup flavors. -Tom Owen, SweetMarias
tdifraia Senior Member Joined: 13 Dec 2012 Posts: 75 Location: Boston Expertise: Just starting
Espresso: QM67 Grinder: Baratza Vario Drip: Bunn
Posted Sat Mar 9, 2013, 9:59am Subject: Re: Temperature Affecting Channeling
Temperature definitely has an effect on flow. The lower the temp. the lower the viscosity, hence the greater the resistance to flow. By heating water it expands and becomes less viscous as its density decreases. The molecules moves faster and are further apart. This resistance to flow will make a difference when making its way thru a coffee bed. Also you must consider the coffee bed itself will heat up and become less dense / compact allowing more water to pass thru. Temperature will have an effect on flow and volume, but I do not think it effects actual channeling of the bed as long as the bed heats up evenly and the Tamp is sufficient.
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,017 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Sat Mar 9, 2013, 1:22pm Subject: Re: Temperature Affecting Channeling
tdifraia Said:
Temperature definitely has an effect on flow. The lower the temp. the lower the viscosity, hence the greater the resistance to flow. By heating water it expands and becomes less viscous as its density decreases. The molecules moves faster and are further apart. This resistance to flow will make a difference when making its way thru a coffee bed. Also you must consider the coffee bed itself will heat up and become less dense / compact allowing more water to pass thru. Temperature will have an effect on flow and volume, but I do not think it effects actual channeling of the bed as long as the bed heats up evenly and the Tamp is sufficient.
Pull a shot on a machine that is cold and just turned on and a machine that is hot, I did. Viscosity of water old and hot may be different but how about the 9bars+ of pressure are we talking about a change of seconds or milliseconds? The 9 bars of pressure lets the water find a week spot to channel through, not 72f water vs 200f water let alone 180f water vs 210f water.
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