Selenium Capacity and Color

[George Collier]

I have read in the threads that tonal color shift is not an indication of archival permanance in toning with selenium toner. So, how do I test the capacity, or the effectiveness of a batch of toner (say, at 1:20, Kodak RST)? How do I know when it's done for, if I don't care about color shift?

 

[Dave Miller]

First ask the question. Is selenium toner archival? Doubts exist.
As to your question, apart from checking your print after 150 years, I have no idea.