I wish I could find the post, but I remember someone writing that the tiny holes in this screen clogged too easily and screwed up the pre-infusion. Yes, I think most of us have signed onto the "layer-under-equal-pressure" model that dismisses the requirement for even distribution through the screen, but that model doesn't really apply during the first few seconds of a slow PI under minimal pressure.

The complaint - that screen clogs cause the initial pre-infusion to soak unevenly into the bed, compromising the puck's integrity and undoing the pre-infusion benefits - stands to reason, at least in the limited context of a thought experiment.

So just for fun, I tried about a dozen shots with half the factory screen blocked off, and slow pre-infusions really did accompany an increase of uneven flows, dead spots and channeling seen via the bottomless PF. In contrast, The GS/3's standard ramp-up is much faster; when using that alternative I didn't observe any consistent differences compared with normal shots without any blockage of the dispersion screen.

Nothing here approaches proof of course, but I've certainly become convinced that even distribution from the screen is more important if you use un-pressured slow-starting drip-drip-drip pre-infusions, and that the IMS screen, if prone to clogging, could unfortunately create just the opposite of the desired positive effect.

shawndo wrote:I have the sproline version and although it is easier to keep clean and it comes with a lower-profile screw, which results in a little more headspace. I haven't noticed any benefit to the actually coffee production. (and I do measure with a refractometer)

IMO a refractometer couldn't inform you about this. Such screens deliver superior group hygiene and little more. A good dispersion is important, but most machines with reasonable water debits have good dispersion with their cheap, stock screens. The refractometer wouldn't tell you about dirty flavors in your coffee from water fouled by contact with oxidized coffee solids trapped in your screen or deposited inside your feed tube, etc. from poor group hygiene. You have to use your taste buds for that.

I like my 'precision' screen (the same one as yours) because this grosses me out. I suspect that frequent detergent backflushing and regular replacement mostly prevents this, but it's better to just have a screen that doesn't have this unnecessary sandwiching of mesh and plate.


Source: instagram

Thank you... that image is incredibly disturbing!

Touché...<hork!!>

shadowfax wrote:<image>

I'm with Crusty Cup and Michael. This screen made a definite improvement on shot quality and consistency in my La Spaziale VII.

TomC wrote:It isn't clear which cleaner is being used to soak these in, I wonder what results would be if they were soaked in a strong hot citric acid solution or something even stronger?

I don't think that citric acid is going to dissolve much if any of what you see above, and something much stronger is likely to attack the screen itself as well.

TomC wrote:As long as the screen isn't dented or damaged, I'd rather see them aggressively cleaned rather than tossed every 2 months.

I agree, but as far as I can tell, you need to be able to scrub the area between the mesh and the perforated stainless sheet. Its not possible to do this on most screens-it's an unhygienic design flaw, IMO. It's unfortunate that doing it right seems to be so expensive, but it is what it is.

I saw on twitter that shadowfax is trying out the IMS screen. From the OP, it looks like it is more than one layer. Is that not the case anymore?
Also, where do you get these in the US?

Interesting thread- here's what I am hearing:
Folks who own, for the most part, expensive espresso machines (VERY expensive many would say), and who do a marginal job during prep for an extraction, will benefit from this screen during the first few seconds of infusion. Maybe. Sounds like a moneymaker to me!