[Alt-photo] Sodium Thiocyanate For Fixing Out Lumens

Ryuji Suzuki rs at silvergrain.org
Fri Aug 18 22:38:44 UTC 2017

In silver-gelatin prints, plates and films, silver image is suspended in 
gelatin layer, which acts as a weak barrier between the air and the 
silver image, as well as holding the image mechanically. In most modern 
silver imaging materials, there is a clear gelatin overcoat that does 
not hold the image.

In salted paper print, this binder is absent. Silver image is almost 
directly exposed to the air.

I would expect salted paper print to be more vulnerable to airborne 
oxidative attacks than silver gelatin IF other conditions are equal 
(including the silver image morphology, residue of any processing 
chemical, etc.). If you were to apply an image-protecting treatment to 
salt prints anyway, it's probably a good idea to include gelatin or 
polyacrylates or some other binder blends that are used in manufacturing 
of silver gelatin materials. Whether additional binder layer will 
significantly increase the protective strength when applied to albumen 
or collodion materials, it's not easy to predict. In collodion plates, 
albumen prints, etc., there is at least some binder that holds the 
image. I don't recall a research that studied relative magnitudes of the 
protection of each material type.

Ryuji Suzuki
"Don't play what's there, play what's not there" (Miles Davis)

On 18 Aug 2017, at 18:03, johnbrewerphotography at gmail.com wrote:

> Ryuji
> Would that apply to other colloids such as albumen?
> Sent from my iPhone
>> On 18 Aug 2017, at 10:40 pm, Ryuji Suzuki via Alt-photo-process-list 
>> <alt-photo-process-list at lists.altphotolist.org> wrote:
>> Ryuji

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