I still have two unused bottles of Feser UV green and two bottles of Feser UV Blue up in the loft from when I was building my first ever loop about 20 years ago and chickened out of using them at the last minute after hearing the horror stories after buying, but before I actually built the loop. Used coloured tube instead always. The Feser green now actually has clumps of god knows what floating around in the bottle!
I think it is true though that it is the famous pH levels which dictate what happens to different dyes an pigments and so forth, so I think dyes can be done, but unless you know exactly how the pH in your loop as at the start, and also crucially how it may change with time, and how that might affect a specific type of dye, then it is going to be pot luck. Safer just to not bother with it.
I think it is true though that it is the famous pH levels which dictate what happens to different dyes an pigments and so forth, so I think dyes can be done, but unless you know exactly how the pH in your loop as at the start, and also crucially how it may change with time, and how that might affect a specific type of dye, then it is going to be pot luck. Safer just to not bother with it.