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

[Paul Viapiano]

Elusive, not illusive  ;-)



----- Original Message ----- 
From: "Ryuji Suzuki" <rs at silvergrain.org>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Wednesday, September 21, 2011 1:59 PM
Subject: [alt-photo] Re: The Illusive Black Cyanotype - Any Insight?


>I doubt salicylic acid would tone prussian blue pigment. The iron in the 
>blue pigment is tightly bound to cyano ligands and salicylic acid is way 
>too weak to undo that.
>
> Salicylic acid was useful in poisoning the redox catalyst activity of free 
> ferrous/ferric ions in ascorbate developers, but that was a very different 
> aim. Even then, I wouldn't be surprised if there were multiple mechanisms 
> involved (e.g., free radical scavenging actions) as I don't think 
> iron-salicylate complex is very stable in alkaline solutions.
>
> In the protocol you described, nitric acid is probably used to decompose 
> prussian blue to free up iron for further reactions. But you don't want 
> the image to become blurry (and lose density) by allowing the iron to 
> freely diffuse in the material, so carbonate solution is used in between. 
> But Mike Ware is the expert to ask on this topic.
>
> If the objective is to convert prussian blue pigment to brown black, 
> another way to do it would be to use a weak solution of sodium sulfide or 
> ammonium sulfide (pH around 6).
>
> -- 
> Ryuji Suzuki
> "Don't play what's there, play what's not there." (Miles Davis)
>
>
>
>
> Gordon Holtslander wrote:
>> Ryuji Suzuki uses salicylic acid in some of his developers to sequester 
>> iron.
>> http://www.digitaltruth.com/data/ds-10.php
>>
>> I wonder if a salicylic acid could be used to clear iron  in toning 
>> cyanotype?
>>
>> Salicylic acid is a phenolic acid like tannic acid.  It may tone 
>> cyanotypes as well.
>>
>> Gord
>>
>>
>> ----- Original Message -----
>> From: Francesco Fragomeni<fdfragomeni at gmail.com>
>> Date: Tuesday, September 20, 2011 4:07 pm
>> Subject: [alt-photo] Re: The Illusive Black Cyanotype - Any Insight?
>> To: The alternative photographic processes mailing 
>> list<alt-photo-process-list at lists.altphotolist.org>
>>
>>> In regard to the gallic acid toning procedure, can anyone
>>> confirm what the
>>> nitric acid does? My assumption is that it is a clearing agent
>>> intended to
>>> aggressively neutralize or remove excess iron residue before
>>> bleaching in
>>> sodium carbonate and then toning in the gallic acid. Can anyone
>>> confirmthis?
>>>
>>> -Francesco
>
>
>
>>>>>> On Mon, Sep 19, 2011 at 9:05 PM, Gordon J. Holtslander
>>> <gjh at shaw.ca>>>  wrote:
>>>>>>> Have you tried this:
>>>>>>>
>>>>>>> To convert Cyano to black tones:
>>>>>>> Place print in solution of 3 drops Nitric Acid added to 1
>>> litre water
>>>>> for
>>>>>>> two minutes transfer to bath of 14g Sodium Carbonate +
>>> 160cc water -
>>>>> leave
>>>>>>> till image disappears and then reappears with an orange
>>> tone transfer
>>>>> print
>>>>>>> to third solution of 14g Gallic Acid + 160cc water - black
>>> tones will
>>>>> appear
>>>>>>> wash 30 min.
>>>>>>>
>>>>>>> perhaps the ferrogallic process would work;
>>>>>>> (from Photographic Facts and Formulas 1940)
>>>>>>>
>>>>>>> ferric
>>> chloride         50g
>>>>>>> ferric suplphate
>>> (basic)        25g
>>>>>>> tartaric
>>> acid                   45g
>>> water                           500 ml
>>>>>>> Dissolve and add
>>>>>>>
>>>>>>>
>>> gelatin                         25g
>>> water                           250cc
>>>>>>> soak gelatin for 30 minutes and dissolve
>>>>>>>
>>>>>>> Development details are not given though
>>>>>>>
>>>>>>> Gord
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