[alt-photo] The Illusive Black Cyanotype - Any Insight?

[Francesco Fragomeni]

Hi all,

I've been working for some time to achieve a black cyanotype but to no
avail. I mean true black and grays, not the purples, eggplants, and other
hues that can be achieved rather easily. I am 100% sure that it is possible
because I have seen examples in private collections. I have also seen a few
rare examples (unsubstantiated) on the web but I've been unable to initiate
conversations with anyone who has made one successfully. I've tried most of
the toning recipes and none of these achieve anything close to what I'm
looking for plus they have a tendency to stain the paper base. Tonight I
tried the nitric acid (nasty stuff so be careful)/ sodium carbonate/ gallic
acid recipe which is purportedly capable of rendering a black cyanotype.
This recipe produced more of a dark grayish purple in the shadows and a much
more obvious purple cast to the highlights. Now this may be worth
experimenting with again because my tests were based on re-soaking already
dry prints rather then making fresh ones which could possibly make a
difference (I couldn't make new prints because I'm waiting on a printing
frame to arrive to replace my unusable one). Can anyone here offer any
insight into how to achieve the illusive black cyanotype?? It would be so
unbelievably appreciated. Thank you!

-Francesco Fragomeni