I ended pre infusion spraying, which causes these:


The cause was spraying above the shower screen that makes its way to the puck. And a really bad one like above will channel pretty badly. I believe this can happen with all lever machines due to the path(s) water must take to exit around the lower piston seal.

Completely by accident I found on Amazon these things called rosin filters. Don't ask what they are for! These are either flat envelopes or tubes. You can get nylon or stainless steel with a variety of mesh sizes starting at 25 microns. I got 9 stainless steel tubes for $17 (1" dia x 5"). One tube was big enough to cut out two disks that fit perfectly above my shower screens (I have two groups). I cut them with standard scissors. They are roughly 0.01" thick.







Once installed, the group now produces a better showering without any ditches in my pucks. I've used these filters successfully on both groups and am very pleased with the result!

Six of the tubes that I got are 25 micron mesh and I used this size on my shower screen disks. I also got three 50 micron mesh tubes. I may make more disks and try them as contact shower screens like the Bplus.

I may also make a few disks for use with my aeropress. I'm thinking a "contact shower screen" on an Aeropress would produce a percolation brew. Fun stuff!