Re: Prussian (Berlin) Blue vs Turnbull Blue in Cyanotype

Quoting Monnoyer Philippe <monnoyer@imec.be>:

> I'd like to try reversal (positive) cyanotype which gives Prussian Blue
> (ferric ferrocyanide). Before ordering potassium ferrocyanide I would like
> to ask you guys how Prussian blue compares to the common (negative)
> cyanotype Turnbull blue (ferrous ferricyanide).
> Is it colder, deeper, ... ?

Both processes form the image from the same blue coloured chemical.
The names refer to the same agent. I haven't used the positive process
so cannot give specific advice. As I remember it needs a binding agent
(like gum) to "stick" the blue to the paper.

Richard

-- 
Richard Urmonas