I have been doing Cyanotypes for a number of years, having got the formula out of the 1947 BJP Almanac, I quite like the way a print appears in the wash water and the simplicity of the process.
I have also visited this thread quite a number of times.
I have a copy of Malin Fabbri's book Blueprint to Cyanotypes and found out about toning them a few weeks ago and have been experimenting ever since. Initially I used tea, Tetley and Yorkshire and at first only got rather yeuky and muddy prints.
I then obtained some Tannin from the local homebrew shop and have been able to get tones from black through to a nice warm brown, and I've been able to keep the highlights reasonably light.
Interestingly I seem to be able to tone in much less time than I read about, I kept seeing hours when I find I can do it in minutes. I've just done one and decided to do it as black as I could get it. I bleached for about 1 minute in washing soda, 1/4 teaspoon in 1.2 litre and then toned in Tannin 20 grams to 1 litre for 9 mins. the paper I used for this one is Canson 'Montval'.
Some years ago I put a 1/2 a Cyanotype print on a window cill and in two days it had faded, some parts of it going yellow, it did not recover in the dark either.
On Friday morning the 16th June I put 1/2 an old Tea toned print, one of the muddy ones in the same place. This time of year the window cill gets full sun after lunch. I've just been upstairs (10:00 pm) to have a look and to compare it with the 'good' half and its fine.
I will post again as soon as something happens or a week passes.
Regards - Jim Read