[Alt-photo] Sodium Thiocyanate For Fixing Out Lumens

Marek Matusz marekmatusz at hotmail.com
Tue Aug 22 16:45:18 UTC 2017


Ryuji

Did u by any chance tested the light stability of the silver images protected with these compounds?
Is it possible that light can catalyze their reaction with silver 
Marek


Sent from my iPhone

> On Aug 21, 2017, at 1:42 PM, Ryuji Suzuki via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> 
> When dry, hardened gelatin and unhardened gelatin have nearly identical behavior. Only when the gelatin is swollen, hardening makes the difference. (The word "harden" is probably not a very good choice but that's what we are stuck with.)
> 
> Wax seems to be an excellent barrier to moisture, especially compared to gelatin (which is only a very weak barrier). So, is this a good practice and recommended? I'm not sure if that's the end of the story. Material compatibility should be looked a bit more closely and in all sorts of scenarios before recommended for practice. There may be several questions like: is the wax pure enough that impurities will not impact the silver image? Is wax good enough barrier to peroxide gas? Is wax stable for many years in normal display condition?
> 
> Usually, we may not know historical materials that didn't work very well because they probably wouldn't survive. One relatively recent example of seemingly good idea that created a new problem is titanium white pigment used in RC paper. It is very bright white pigment, and it is archival quality but it generated oxidizing agents when exposed to light and untoned silver image deteriorated, but only when the prints were sealed in a frame or container.  Another example is acetate film base. Acetate film base deteriorates faster when stored in closed containers, and it is very important to let the film breathe in cold dry air to ensure long storage life (Tri-acetate is better in this regard, but many tri-acetate bases, especially early ones and ones from less sophisticated manufacturers are more like 2.5-acetate rather than 3-acetate). Some dyes used in color materials also keep better in presence of fresh air than closed or vacuum environment. So, it is not always a good idea to seal everything.
> 
> If you work with printed out silver image, prefer not to tone, and currently having less than ideal image stability, I'd once again recommend silver image protecting agent that acts on silver directly without altering it. In my experience with silver image, even a simple treatment with 2-MBI or PMT increased the image durability in high humidity peroxide gas, and these treatments do not alter the image or the print surface. 2-MBI is cheap and traded in massive quantities. You might want to test with your material.
> 
> Ryuji Suzuki
> "Don't play what's there, play what's not there" (Miles Davis)
> 
>> On 19 Aug 2017, at 1:05, Serdar Bilici wrote:
>> 
>> Ryuji
>> 
>> Does the  gelatin as a protective layer needs to be hardened ?
>> 
>> What about waxes for making a protective layer? I tested the waxed salt
>> prints by putting them in iron blue toner, the waxed areas don't even get
>> wet.
>> I was thinking that wax on print creates an excellent air and moisture
>> barrier.
>> 
>> 
>> Regards
>> Serdar
>> 
>> 
>> 
>> 
>> On Sat, Aug 19, 2017 at 1:38 AM, Ryuji Suzuki via Alt-photo-process-list <
>> alt-photo-process-list at lists.altphotolist.org> wrote:
>> 
>>> 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
>>>>> 
>>>> _______________________________________________
>>> Alt-photo-process-list | altphotolist.org
>>> 
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