Re: pigment

Well, that's interesting isn't it. If it's the same compound, as Jack
or someone said, then why would it be permanent as a cyanotype and not
as a pigment? And why some brands permanent and others not? (And no,
contrary to popular myth, this is not true of most pigments; this is
the only one I know of where the variability of permanence across
brands is worth noting; usually the brands vary by only a couple of
point on an 8-point scale.)
Katharine

On Nov 22, 2005, at 7:38 AM, Marek Matusz wrote:

> All,
> This question of cyanotype or prussian blue permanence has beem
> lingering in literature for a while. Yet there are plenty of examples
> of perfetly good looking cyanotypes from hundred years ago. I have
> been conducting my own stability tests on the pigments that I am
> using. I t has been a couple of months and we do get a lot of sun
> exposure in Texas. I will report which pigmets do well in a few months
> (prussian blue from Daniel Smith is one of the pigments tested).
> Marek, Houston
>
>
>> From: "Christina Z. Anderson" <zphoto@montana.net>
>> Reply-To: alt-photo-process-l@sask.usask.ca
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: Re: pigment
>> Date: Tue, 22 Nov 2005 07:05:29 -0700
>>
>> I'm going to throw out something here you all can hash over.
>>
>> I don't use Prussian blue just because of some brands' purported
>> fading in sunlight and recovering in the dark...Maimeri, Sennelier,
>> Schmincke, Wand N...
>>
>> Page says she has not seen it recover.
>>
>> Whether this is fact or fallacy, thalo works so much better with more
>> color saturation and clearer and smoother. But it seems to me that
>> this chance would be akin to working with Alizarin nowadays when
>> there are better, permanent reds.
>> Chris
>>
>> ----- Original Message ----- From: "Jack Fulton"
>> <jefulton1@comcast.net>
>> To: <alt-photo-process-l@sask.usask.ca>
>> Sent: Monday, November 21, 2005 10:15 PM
>> Subject: 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 Tue Nov 22 10:31:44 2005