Hello,
I've just read in an older publication (Die Ilford Positivtechnik by Jost J. Marchesi) the recommendation of testing wash water for hypo content with a Pot. Permanganate / S. Carbonate solution.
For the record, here's the recipe (I paraphrase as the publication I have is in German):
Pot. Permanganate 0.1g
S. Carbonate (sicc.) 2g
Aqua dest., fill to 100g
Put a drop in a sample of the wash water. If the time it takes for the color to disappear is longer than one minute, the hypo content is under 0.001% and washing sufficient. Do a parallel test with fresh tap water for comparison.
Any opinions on it? Has it not proven reliable, as what seems to be recommended these days is the Kodak HT-2 residual hypo test with Silver Nitrate/Acetic Acid?
If it is a good approach, how long lived can I expect the solution to be? Special requirements for purity, is drugstore washing soda ok?
Now that we're at it, same question for HT-2 if I decide to go that route; is distilled vinegar ok or does it require acetic acid of higher purity?
I've just read in an older publication (Die Ilford Positivtechnik by Jost J. Marchesi) the recommendation of testing wash water for hypo content with a Pot. Permanganate / S. Carbonate solution.
For the record, here's the recipe (I paraphrase as the publication I have is in German):
Pot. Permanganate 0.1g
S. Carbonate (sicc.) 2g
Aqua dest., fill to 100g
Put a drop in a sample of the wash water. If the time it takes for the color to disappear is longer than one minute, the hypo content is under 0.001% and washing sufficient. Do a parallel test with fresh tap water for comparison.
Any opinions on it? Has it not proven reliable, as what seems to be recommended these days is the Kodak HT-2 residual hypo test with Silver Nitrate/Acetic Acid?
If it is a good approach, how long lived can I expect the solution to be? Special requirements for purity, is drugstore washing soda ok?
Now that we're at it, same question for HT-2 if I decide to go that route; is distilled vinegar ok or does it require acetic acid of higher purity?
Last edited: