Quote Originally Posted by ronlamarsh View Post
I have read in Tim Rudmans toning book of tea toning cyanotypes he claims they are permanent.
I have one made using the carbonate bleach/tannin tone method outlined in the article that I put in a position where it gets sun for about an hour every day. Going on two years now, and with no visible change compared to a control print made at the same time and kept under favorable conditions. Hardly scientific, but good enough to give me confidence in the process to this point.