|
|
|
-
-
Since it's probably a silver chloride paper, couldn't kosher cooking salt act as a restrainer, aka anti-fogging agent? Chemists, feel free to shoot it down.
I see Peckham Amidol uses sodium chloride, presumably as a restrainer:
http://unblinkingeye.com/Articles/Amidol/amidol.html
-
Sodium Chloride is a weak restrainer for silver chloride papers. It is no where near as effective as Sodium Bromide is for any paper.
In high concentration, it can cause a big speed loss and contrast increase due to its severe solvent effect on Silver Chloride itself.
PE
-
How about benzotriazole??..EC
-
Benzotriazole is a strong restrainer for Silver Chloride papers. It works just fine. There may be a slight cooling in tone, depending on other addenda.
PE
-
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
-
I should add that the neg I printed was quite dense so the paper is clearly no longer a grade 3. Well that is to be expected of course with paper of this age.
How much sodium bromide and/or benzotriazole would one add to a developer to help the fog? The paper, to my eye has a little fog and lowered contrast. The posted scan is a litte off, its not quite as flat as that in the actual print but it could benefit from some anti fog agent. I wonder how much do you use?
-
Adding an antifoggant will not fix the apparent contrast problem AFAIK. It will give you white on gray instead of gray on darker gray.
Benzotriazole probably would be best. I would start at 1 mg/l and you could need to go up to 10 mg/l. I would test the paper after each incremental addition, so at 1 mg, 2 mg, 4 mg etc, and at some point the fog will vanish. Speed will also decrease. With this paper, you may even need to go higher.
Sometimes you are chasing your tail though. You add BTAZ and lose fog and speed so much you have to develop more and that gives fog, and etc....
PE
-
 Originally Posted by Photo Engineer
Adding an antifoggant will not fix the apparent contrast problem AFAIK. It will give you white on gray instead of gray on darker gray.
Benzotriazole probably would be best. I would start at 1 mg/l and you could need to go up to 10 mg/l. I would test the paper after each incremental addition, so at 1 mg, 2 mg, 4 mg etc, and at some point the fog will vanish. Speed will also decrease. With this paper, you may even need to go higher.
Sometimes you are chasing your tail though. You add BTAZ and lose fog and speed so much you have to develop more and that gives fog, and etc....
PE
I have many boxes of 1984 SW Kodabromide 5x7 G3 which behaves like a beautiful G1.5. Incidentally no fog.
I have only found 2 workarounds.
1- Make a dense print, selenium tone heavily and then bleach back.
2- Develop in normal developer till a ghost image appears, brief water rinse, finish in dilute lith developer. A beautiful black can be had - with practice.
Mark
Mark Layne
Nova Scotia
and Barbados
-
If fog is a problem reversing the procedure might work, lith first then normal developer. This is somewhat similar to Moersch Polycrome procedure which might work with old Kodabromide as nothing will induce color in this paper.
Mark
Mark Layne
Nova Scotia
and Barbados
-
I was looking again at that chlorohydroquinone post referenced in post #11 at Michael and Paula's web site. It seems to me that the large scale synthesis of that developer and one other were stopped about 10 - 20 years ago due to the toxicity of some of the intermediates if not the actual compound itself. I got this from a friend who used to make it. So, I'll have to follow up on this, but only if there is interest. I could also ask Grant Haist. There was no work done with this while I was at Kodak, but a lot of work had been done before I joined the company.
The other item rather amused me. Ryuji Suzuki is not a PhD yet. AFAIK, he is a graduate student in a track outside of chemistry or physics. He is quite knowledgable on both subjects however.
PE
|
|
Adv Reply
