La Marzocco High Dose Group Shower Screen

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Dodger1
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#1: Post by Dodger1 »

https://www.chriscoffee.com/La_Marzocco ... 054756.htm

So far it appears to offer a slight improvement in the body of my shots, over the OEM screen, but I was wondering if anyone else has any observations that they'd care to share.

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shawndo
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#2: Post by shawndo »

I'm skeptical about these, at least in terms of "adding body and roundness"
I splurged on one of these http://www.espressoparts.com/EP_TX_SCREENKIT_LM last year and didn't notice any difference except for the ability to dose a little more than I could before. Although the higher dosing ability appears to be enabled by the lower profile screw that was included, not the screen itself. It doesn't look like the one you linked comes with a screw. Not sure why it's called a "High Dose" screen then.
I wonder if we can even tell the difference when the screen is completely removed. Especially if you do a line-level preinfusion.
Darmok and Jalad at Tanagra

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shadowfax
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#3: Post by shadowfax »

shawndo wrote:Not sure why it's called a "High Dose" screen then.
I've seen many "domed in," deformed screens on espresso machines at cafes where the baristas often use high doses. If you dose to the point that the puck almost touches the screw, the wet puck will expand at the end of the shot when pressure is relieved and press firmly against the screen. Eventually it tends to fail under this pressure and the convex dome from the factory is reversed. As a result, they don't fit the group properly anymore, leaving spaces around the edge for coffee particles to shoot back into the feed tube upon pressure relief.

The video in the OP demonstrates that this screen is more resistant to deforming under pressure because of the thicker metal used. I would consider all the claims about a more even dispersion suspect, but this is why it's called a "high dose" screen.
shawndo wrote:I wonder if we can even tell the difference when the screen is completely removed. Especially if you do a line-level preinfusion.
I think dispersion is important, but I agree that the basic screen does a fine job of this. I share your doubt that any of these precision screens materially improve dispersion in a way that would consistently improve shots. If you take the screen off, you'll take a whole bunch of coffee into the tube when relieving pressure and most likely clog your feed tube and your 3-way solenoid valve. The buildup that bakes onto the inside of the tubes will also impart muddy, hotpot, spoiled coffee flavors to your shots. You'll definitely notice that.

Like I mentioned in IMS precision screen discussion, the function of a shower screen is about hygiene as well as dispersion. A perfectly prepared puck pulled with perfect dispersion still tastes noticeably off (if not totally disgusting) when pulled on a dirty group, and screens that are hard or impossible to clean contribute to this effect.
Nicholas Lundgaard

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shawndo
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#4: Post by shawndo »

shadowfax wrote:the function of a shower screen is about hygiene as well as dispersion.
I'm totally bought in in terms of hygiene. The sproline shower screen from EP is just a single slab of metal, which seems fairly simple to keep clean. I can't even touch the OEM screen anymore after seeing your other post!.

The screen from the OP looks like it is layered like the OEM though...
Darmok and Jalad at Tanagra

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shadowfax
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#5: Post by shadowfax »

Yes, agreed. The high dose screen won't collapse over time from high doses, but it looks like it's basically the same as the stock screen otherwise. It's only the Sproline/IMS screens that eliminate the impossible to clean crevices, from what I can tell. I'm working on getting a sample screen from a well taken care of home machine to cut up and examine to see if it's anywhere near as gross as that picture I located previously, which was likely from a machine used with commercial volume.
Nicholas Lundgaard