Re: pigment

Yes, the 'blue' of the cyanotype is Prussian Blue. The cool thing
about it is that it was the first true blue that was what one might
call inexpensive. It came around in the early 1700's, so Herschel
knew all about it when developing the cyanotype.

One interesting anecdote for today's climate of terrorism is that
Prussian Blue and Potassium Iodide can be ingested to aid in the
removal of radioactive materials from the body. Both of these are
chemicals of our medium. The FDA approval of Prussion Blue is either
coming up or was recently approved. The U.S. is stockpiling capsules
of it.
Jack Fulton

On Nov 21, 2005, at 8:49 PM, Katharine Thayer wrote:

>
>
>
> On Nov 21, 2005, at 6:55 PM, Dave Rose wrote:
>
>> Isn't Prussian Blue the same pigment/chemical that forms cyanotype
>> prints?
>
> Is it? I guess I've never heard or thought about what the final
> product is that forms a cyanotype print, but Prussian blue is
> hydrous ferric ferrocyanide or feriammonium ferrocyanide, is that
> what it is?
>
> To my eye, Prussian blue pigment has a greener cast to it than most
> cyanotypes I've seen, or than pthalo, which to my eye has probably
> the purest cyan hue for tricolor of the blue pigments available,
> followed by ultramarine. And to me it's a duller blue than either
> pthalo or ultramarine, and for those two reasons I didn't suggest
> it for tricolor. But I can't say for sure that it's not good for
> tricolor, because I've never tried it. I guess I was also
> influenced by someone who wrote the other day that he had tried
> Prussian for tricolor and it didn't work well at all.
>
> I feel another test
> kt
>
Received on Mon Nov 21 23:16:26 2005