Re: Toning Cyanotype

I think the idea that tanic acid toned  cyanotype are not permanent is another myth like the one about cyanotype itself not being permanent. I have some, at least, ten year old cyanotypes that were toned with tanic acid that show no sign of fading. I also have a cyanotype postcard with a 1904 postmark that looks just fine. If you are worried, why not put a toned cyanotype in a sunny window for about a month. Cover one half with black paper. That ought to give you some idea.

Bob Schramm