After trying quite a lot of different papers with both classical and MW cyanotype I noticed, that all my cyanotypes fades at drying - just opposite the dry-down. When picture is OK when wet, it becomes to pale when dries up - let say for minimal one zone.
First I thought that our water contains too much carbonates, so I washed my pictures whole time in acidified water (with citric acid) and fading was again there.
Anybody has an explanation of that effect? (I looked at archives and did't find any answer).