Stannous chloride foggant recipe
I'm online from my basement, developing a roll of Agfa Apx100 as slide.
I've used this foggant recipe:
Part A (buffer):
16ml acetic acid 80%
32g sodium acetate trihydrate
0,5g stannous chloride
So far so good: the image is uniformly fogged. The problem is: the part A + part B after a while turns cloudy, especially after being used.
Is it normal?
1) I░ developer: Fomatol P 1+0 + 4g/400ml hypo + 20ml Rollei RMB5;
2) stop: 2% acetic acid;
3) wash 5-10-20;
4) bleach: 2g/1000ml potassium permanganate + 55g/1000ml sodium bisulfate;
5) wash 5-10-20;
6) clearing: 25g/1000ml potassium metabisulphite;
7) wash 5-10-20;
8) foggant: foggant recipe (acetic acid/acetate buffer) + 0,2g/400ml stannous chloride;
9) wash 5-10-20;
10) II░ developer: D76 1+0 + 20g/1000ml sodium carbonate;
11) wash 5-10-20;
12) fixer 1+9;
14) selenium toner 1+20;
1) 12min, 5 inversions every minute;
4) 5min 1 inversion every 15 seconds;
6) 3min, 5 inversions every minute;
8) 2min, 5 inversions every minute;
10) 6min, 5 inversions every minute;
12) 4min, 5 inversions every minute;
14) 4min, 5 inversions every minute.
With use, as acidity drops, it can become cloudy. A chelating agent would probably help.
Acidity drops mean that pH goes below the buffer pH?
I've designed the buffer to have approx pH 4.6. Now the question is: how can the foggant bath go below pH 4.6?
There's a buffer to prevent it...
And the step before is water so there's not any alkaline or acidic carry-over...
Well, SnCl2 can do this SnCl2 (aq) + H2O (l) is in equilibrium with Sn(OH)Cl (s) + HCl (aq) and this can cloud up. It can take place even in acid.
Adding some ETDA should help.
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Ok, got it.
Another chemical powder on the buy list!
So, if I measure the pH after the bath has turned cloudy, I should get a reading below 4.6 right?
Tomorrow I'll try.
P.S.: glutaraldehyde works wonders!!!
It might be 5.0 or higher by now, but the formation of the precipitate goes on, once started and in the absence of a chelating agent. That is the purpose of the other ingredients in the Kodak reversal bath. It prevents the precipitate from forming.
There's something wrong with my pic above.
Maybe too much hypo...