Thanks! The material for the wear rings for the piston as well as for the "wipers" is PTFE, the "whiter" looking white. The smaller, slightly transparent wear rings for the piston rod is from polyamide PAS 60. No deeply founded rationale for the choice, but simply what I had available. You assume right: Self made. Not sure the "wiper" will actually wipe (that´s my reason for the quotation marks
). Some of them don´t have the smallest diameter at the very end. Will probably redo them when I get a better turning tool.
Stefan