Backflush question.

la marzocco, synesso, simonelli, cimbali etc

Backflush question.

Postby Ed Kaufmann on Mon Oct 06, 2008 7:15 am

It seems that there is a little bit of confusion in the industry about whether or not the dispersion screen and screw should be in the machine when backflushing the group of a Synesso or any espresso machine for that matter. I always though that it absolutely had to be in when backflushing because one would not want to get coffee gibletts stuck in the threads. That rule seems to be the exact opposite of what some of my respected peers say. I am hoping for a little clarification. Thank you.
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Re: Backflush question.

Postby James Hoffmann on Mon Oct 06, 2008 10:42 am

I tend to chemical clean with screens in, but only after dropping them and cleaning them and the grouphead thoroughly first.

I have, in the past done chemical cleans without the screens in and never had a problem with it.
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Re: Backflush question.

Postby Alistair Durie on Mon Oct 06, 2008 5:00 pm

We backflush the group head and clean the screens & screws separately.
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Re: Backflush question.

Postby phaelon56 on Mon Oct 06, 2008 6:41 pm

The big "gotcha" is to make absolutely certain that no one jumps in to lock in a filled PF and pull; a shot when you have the dispersion screen removed from that brew group. THAT is a very bad thing.... (and no I haven't done it myself but had this fact drilled into my head by a person I trust who has seen the sad results).
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Re: Backflush question.

Postby Kyle Glanville on Mon Oct 06, 2008 6:56 pm

Either way - no problem. We clean the group, gaskets and portafilters every forty minutes. Half of the time we drop the screens and soak em, the other half we don't.
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Re: Backflush question.

Postby Ed Kaufmann on Mon Oct 06, 2008 10:51 pm

Kyle, when you drop the screens every other time you clean the groups, gaskets and portafilters, what do you soak the screens in? Hot water? How long do you let them soak?

So just to clarify, if your group head and blind basket are completely clean, there is no problem with backflushing without the screen and screw in. Is this correct? Does anyone do this throughout the day or just at the end of the night?
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Re: Backflush question.

Postby Emily Oak on Tue Oct 07, 2008 1:41 am

phaelon56 wrote:The big "gotcha" is to make absolutely certain that no one jumps in to lock in a filled PF and pull; a shot when you have the dispersion screen removed from that brew group. THAT is a very bad thing.... (and no I haven't done it myself but had this fact drilled into my head by a person I trust who has seen the sad results).


I know someone who DID do this, to a Mistral, and lets just say, it took days to take the whole group apart, clean out the grinds, and get it up and running again.

:-)
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Re: Backflush question.

Postby Drew Cattlin on Tue Oct 07, 2008 8:15 am

ed,

i think very frequent clean-water-backflushing of intact groups with a blind disc is crucial on a busy bar with those nickel-plated brass portafilters. get the spent grounds out.

breaking down a group at a time, taking the screws and screens off while the bar is open would be great, but you'd need enough functioning groups to keep those drinks flowing without slowing service.

i've been told david schomer would teach vivace to break down groups and detergent-backflush twice daily, and to clean-water-backflush and scrub baskets/portafilters at least every 45 minutes (or more, depending on business).
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Re: Backflush question.

Postby nick on Tue Oct 07, 2008 8:56 am

As you may or may not know, backflushing on a LM or Synesso is about blowing clean (or detergented) water through the drain-side of the 3-way solenoid valve, as well as the distance between the shower-head and the 3-way valve.

On the Linea/FB70's and older GB5/FB80's, it's a relatively long distance: from the shower head, down the banjo tube, out the side of the group neck, and around to the 3-way solenoid (which hangs like a pendant-necklace below the group neck). It's a long distance to have to blow water out of... maybe an ounce of volume?

On the newer GB/5's, FB/80's (with Piero caps) and the Synessos, that distance is a lot shorter. This is one of the reasons that the gicleur/flow-restrictors on the Piero-capped LM's need to be smaller than 0.6mm to produce a similar pressure ramp-up. The location of the solenoid is also why there's more water dripping when you kick-off the group on a Piero-capped LM with the portafilter out.

The difference between backflushing with the screen in or out... well... people know I'm all about bizarre, irreverent analogies... so here it goes: backflushing with just water (or detergent) is like going pee-pee. Whether or not you have the screen in is pretty much irrelevant. If you were to go #2... well... ok, forget it. I'm abandoning this analogy right here.

The point is, if you were to try to brew espresso with the screen out, when you kicked off the group, a quantity of the water-soaked grounds would get blown/sucked up into the tubing. Normally, there's a screen in place to keep (most of) the grounds out when you kick off the group. The 3-way solenoid is fairly small in diameter where the action happens in the valve itself, and it'd be pretty easy to muck it up with even a small amount of coffee grounds... but it'd have to be a lot more than you'd normally encounter when backflushing after removing the screen.

That all said, I think that if there's a rule of thumb here, it's that you should always do your best to keep the shower-head and group gasket area clean. This includes having strong group screens. Weak screens will pop up and let grounds sneak in around the dispersion screw hole, which could mess up your machine, and dirty your shower-head area. I also see a lot of baristas flushing their groups, but not nearly enough that wipe the screens too.

Ed, best-case, in my personal opinion, backflush with the screens in. Not because you'd hurt the machine otherwise, but because it forces clean water up and down the screen, possibly dislodging some particles from the mesh in the screen (can you say, "lessons learned the Clover?" :wink: ). Merely soaking the screens in espresso machine cleaner won't dislodge particles as well as backflushing with the screens in would. However, backflushing with the screens removed won't hurt. Just keep the areas clean!
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Re: Backflush question.

Postby Ed Kaufmann on Tue Oct 07, 2008 7:31 pm

Nick, totally different discussion but when you wipe the screen with a rag after every shot, aren't you just rubbing the existing grounds into the screen. What about a good flush after removing the pf to dose and then another good one before locking and loading for the next shot. No Wipey? (I think I learned that from you, no?...sorry we have a new Canadian on staff. I can't stop saying "no?").
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Re: Backflush question.

Postby nick on Tue Oct 07, 2008 7:54 pm

I like to wipe when knocking out the puck when there's a break on the bar.

Remove pf, flush, knock out the puck, rinse the pf well with the hot water tap, wipe, flush, reinsert. The last flush takes care of rubbed-in grounds... and don't apply pressure, just wipe it clean. Wipe, don't rub.

And you listen to Amber when she says "no," mister!
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Re: Backflush question.

Postby Luke Shaffer on Thu Oct 09, 2008 9:53 am

Good discussion... I've often wondered the same thing. I was concerned about the groups not being "clean enough" before backflushing with screens out so I've settled on the following end of day routine:
  • Drop screens and screws
  • Remove baskets, spring clips from PF's
  • Put all of the above with the pf's in a big pitcher of hot cafiza water
  • Brush out big stuff from the groups
  • Use a damp towel and wipe the gaskets/lock-in area/basically everything
  • Go do something else for a little while
  • Dump out the cafiza water & parts, rinse off, reinstall
  • Backflush with cafiza
  • Rinse the heck out of the groups

Since we only have a 2 group Synesso it's hard to do the full cycle during the day without getting ourselves in trouble, so at best we do the above without detergent soak/backflush or the above without removing the screens.

I also encourage regular screen wiping as Nick described above- with a DRY towel. I learned that the hard way from our Clover! Also thanks to his bathroom analogies I'm now going to refer to the post-shot flush as the "courtesy flush". Toilet humor is a great way to reinforce proper bar technique.
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Re: Backflush question.

Postby Ellie on Fri Oct 10, 2008 5:32 pm

There is an article in the forthcoming B-mag that discusses espresso cleaner and what it does, what it's made of, how it works and how it should work, etc. My friend Josh over at Urnex gave me a sneak peek of the article (which also features an articulate and highly specific series of interview questions from a WBC champ) and it is really, really good. It is kind of embarrassing to be this passionate about detergent...but honestly in my experience, neglecting the cleaning is the single most common mistake made bythe typical espresso purveyor (restaurant, coffee house, whatev) and probably the easiest to fix. The unclean machine drives me absolutely nuts. It is delightful to see this topic discussed here and there, too.
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Re: Backflush question.

Postby Alistair Durie on Sat Oct 11, 2008 12:24 am

We like to keep an extra set of screens on the bar, so during the day we can quickly swap out our screens for nice clean ones and take our time to clean the others.
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Re: Backflush question.

Postby fleck on Mon Mar 23, 2009 12:16 pm

Ed, best-case, in my personal opinion, backflush with the screens in. Not because you'd hurt the machine otherwise, but because it forces clean water up and down the screen, possibly dislodging some particles from the mesh in the screen (can you say, "lessons learned the Clover?" :wink: ).


good points by all. back when i first started working at the stumptown i initiated a more frequent cleaning schedule for the machines which included clear-water backflushing throughout the day every hour or so. at nights, we would remove screens and screws and detergent backflush without them. over time however, we would still run into flow problems, especially on our older, custom mistrals. after a while, alex, our service guy, removed and disassembled the group valves on one of our machines and it looked like a thick layer of crack rock had built up around our group valve on all the groups. it turns out that the cleaner we were using (which we also realized was part of the problem) didn't dissolve very quickly and if the screen wasn't in place to break it up, it would build up like plaque in the valve. i've noticed that cleaner that has been sitting around for a long time also tends to loose its dissolvability, which can lead to the crack rock problem.

after we made it a standard protocol to ALWAYS remove the screens, clean them, replace them, and then backflush, the issue went away. so yeah, i would recommend to keep them screens on!

--stephen
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Re: Backflush question.

Postby Les Quon on Tue Mar 24, 2009 10:23 pm

Puro-crack..

Crack-fiza




Thanks Stephen, for my latest addition to my " Learned something new" file..
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ibex$$$1989@$$$yahoo.com
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Re: Backflush question.

Postby Luke Mutton on Sun Apr 12, 2009 12:47 am

We backflush with screens in and out at the end of the day. Chemical without the screens in. We chemical the screens seperately.
One interesting and ... well it looks to be beneficial piece of info that we obtained reading a manual to a new Linea. Place the shower screens over a flame and what this does is burn off any carbon buildup!! Test a flamed used screen against a used screen and the difference is noticable.
Have not tested the taste difference but would be interested if anyone has

KW
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