I've just changed gaskets and while I was at it thought I might as well pop in a new showerscreen. I was surprised to see quite a different water flow. When I saw it, I recalled that was what it looked like when the machine was new.

OLD SCREEN



NEW SCREEN



Now the old screen was regularly subjected to chemical cleaning, both through backflush and removal. The old and new screens look the same, with no obvious blockages that would cause the different water dispersion.

Old screen on the left in both pics...





The only thing that I could see that was at all different was that there was a very small amount of grounds/fines stuck between the wire mesh and the more solid metal frame. Hard to see and not that much of them, but in about the 630 position, 2 holes from the outer edge.



Perhaps this is channeling the water differently... Anyhow, I thought it mildly interesting.

Cheers, Chris

The local espresso maintenance gurus suggest fire.
Put the thing over a gas stove flame until it stops smoking, and begins to orange up. Once the thing gets all of the particulate matter turned to ash, let it cool, and wash it away under a faucet. Take your old one and hold it to the fire til it glows, cool it rinse it, and compare it to the new one.

Are you sure that the flow difference you're observing isn't just a wet screen vs. a dried screen? I've noticed that a lot of espresso machines (my Elektra, Vetrano, and GS3) would flush a bit differently (very similar in difference to your two contrasting flush picturess) if you flush with a wet screen vs. flushing after drying the screen thoroughly.

What's your screen cleaning regimen? It might be a good idea to pull it more often and let it soak in a super-hot Cafiza solution.

On my Anita, I noticed the same thing after putting in a new shower screen.

I backflushed every 7-10days, regularly. On those days, I dropped the Screen/Gasket, and soaked them, along with my baskets and PFs. Scrubbed everything.

Then at the 6 months mark, I changed the shower screen. The water flow was similar to your second picture, and my old shower screen also had little bits of fines that I just could not get at to remove.

Nicholas does make a good point.. I did notice some difference between a dry screen/wet screen flushes.. but not as large of a difference as I noted with the new screen. Weird.

On my VII... I drop the screens every three days. When I put the clean ones in, the water flows perfectly even, all the way around the screen. Wet or Dry. On day 3(sometimes 4), the water is always leaning to one side, wet or dry. .. Which is what reminds me to change the screen. When I FIRST had the VII home, I was having channeling issues, and thought this was the cause of it. Its not, it was me. But I still change the screens every 3-4 days, because I can taste the coffee stuck in the screens affecting the cup.(due to the VII's screen design, of using two of them to trap grounds, and keep them out of the solenoid path.)

Have you ever tried "descaling" your screens? I think there's some chance that they scale up in the spaces that don't get brushed out. screens (and baskets) are both in situations where they get wet and then dry out by evaporation, which is the type of thing that can cause buildup of limescale. Soaking them in a decent solution of citric acid for a few hours once in awhile might help this. I am shooting from the hip here, though, based on a comment from Eric s. awhile back about basket holes scaling up.

I'm still skeptical that this is a real problem, though. Do you guys notice a performance change of any kind? I'm guessing it's easy to turn this into a dragon-chase...

Should be easy to see if there's any scale buildup or other debris with a high-power magnifying glass or low-power microscope. I have a range of devices between 10x-100x, and will check it out when I get a chance (kind of a busy time of year... )

shadowfax wrote:I'm still skeptical that this is a real problem, though. Do you guys notice a performance change of any kind? I'm guessing it's easy to turn this into a dragon-chase...

On my Anita, I didn't even notice the change in the way the water flows until I put the new screen on, because it was so gradual. I didn't notice anything.

On my Vivaldi, its a different ball game. As you may know, its got the D-Block and two screens, which are supposed to trap coffee grounds to keep them out of the 3way solenoid and such. You get two sets, with the idea that you'll change them every 3-4 days or so. Ive been doing just that. When you put new screens in the water flow is picture perfect. after the couple of days, it looks like the first picture. I thought I was getting channeling because of it, but it was classic PBTC syndrome of blaming the machine. But they still need to be changed every few days, because you can taste the grounds caught in the screen affecting your shots.

So no.. performance wise, I didn't notice a difference on my Anita, and besides taste, no difference on the VII. Maybe there would be after a week, or two... But Im not going to suffer through the stale/burnt/bitter tasting shots to find out

As an aside. . . Is anyone subscribed to the EPNW E-Letter? I think it was the last issue, where they had a poll, asking how often people changed the group gasket/shower screen. They suggested changing out the filter baskets at the same time gaskets/screens were changed out. . and were surprised at the amount of people who didn't change baskets out frequently. Am I correct in assuming that was directed towards the cafe' owners and Barista's? I can't imagine that, at home, baskets are only good for the life of a group gasket.. but Im ready to be told otherwise if that's the case. . .

JmanEspresso wrote:As an aside. . . Is anyone subscribed to the EPNW E-Letter? I think it was the last issue, where they had a poll, asking how often people changed the group gasket/shower screen. They suggested changing out the filter baskets at the same time gaskets/screens were changed out. . and were surprised at the amount of people who didn't change baskets out frequently. Am I correct in assuming that was directed towards the cafe' owners and Barista's? I can't imagine that, at home, baskets are only good for the life of a group gasket.. but Im ready to be told otherwise if that's the case. . .

You know, I think I get that newsletter as well, but I obviously didn't read it thoroughly enough. Everything in me groans against making these stainless steel parts so disposable. I'm not a cheapo or an environmentalist per se, but it sounds over the top and I'd want some real hard evidence to convince me that keeping baskets and screens clean and potentially descaled before I start tossing them every 4 months or so... which is how long my first GS3 gasket lived. I never got anywhere near the sealing problems EPNW was quizzing about; my simple test is pulling the gasket and flexing it. If it cracks, it's time to put in a new one. Anyway, so it's 4 months plus a few days since I got my GS3, and earlier this very week my gasket failed this test. My Synesso double basket has lived through around a year of daily use now, and the screen is pristine as well. It just seems silly to toss either.

I don't descale the shower screen, but I don't think I really need to judging from my recent look inside my boiler! Regular Cafiza soak, and of course backflush. I also doubt it changes anything, I was simply surprised by the difference, visually. Oh, and both screens were already wet from after a couple of shots.

Ref the EPNW poll, its interesting that the only spare parts provided with my machine are a spare showerscreen and gasket, not filter baskets.

Cheers, Chris

OK, an espresso imponderable...

gyro wrote:The only thing that I could see that was at all different was that there was a very small amount of grounds/fines stuck between the wire mesh and the more solid metal frame. Hard to see and not that much of them, but in about the 630 position, 2 holes from the outer edge.

There may be impurities adhering to the old screen that disturb the water's laminar flow (i.e., water flowing around a rough versus smooth surface). Jon's suggestion to burn it clean should eliminate that possibility.