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Thread: Pyrogallic acid

  1. #21

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    you forgot the further dilution for the working formula. 10.5 grams add 700 ml of water and you get about 0.7 or 0.6 I dont know .....terrible doing figures in my head.

  2. #22
    c6h6o3's Avatar
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    No, I didn't forget. Each 1 liter batch of B stock solution contains 105 grams of sodium sulfite. When you dilute that by placing 100 ml of that B stock into 1 liter of working solution (1:10, since 100ml is 1/10 of 1 liter), you end up with 10.5 grams of sodium sulfite in the 1 liter of working solution. To substitute 0.4 grams for this is to be short on Solution B by more than an order of magnitude. Just what am I missing here?
    Jim

  3. #23

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    No no no......ok each liter of stock solution has 105 grams, this is aprox a 10% solution, agree?
    Ok so now we take 100 ml of the stock solution, now we have only 10.5 grams...(10% solution). Were are now further diluting these 10.5 grams in 900 ml..(water+C+A) to make .105 concentration of sulfite aprox. In your previous post you missed a step.

    Or in other words your calculations assume that 100 ml have 105 grams not 10.5 grams. Read your post again and you will see I am correct.




  4. #24
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    All I really need to know is that there must be 10.5 grams of sulfite in the liter of working solution + 100 ml of Solution A (pyro, bisulfite and KBr) + 100 ml of Carbonate (solution C). So, I'll just mix 100 ml of the 10.5% sulfite solution for each development session and voila! My sulfite will always be fresh. Thanks for the tip, Jorge.


    Jim

  5. #25

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    Sure you are just making 100 ml of B stock solution everytime...you can do it that way or like me just add the pinch to the working solution.
    In any case you will be using fresh sulfite everytime and will be more consistent....you are welcome.

    OTOH hand it is not the working solution but the stock solution you are talking about. Please be aware of this. If you put 10.5 in the working solution you will get no stain....I promise you that.




  6. #26
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    Mixed up a fresh batch of pyro stock solutions last night. This time, though, I only made A and C solutions. Then I mixed the sulfite and developed some negatives. Perfect. Beautiful image stain and virtually no general stain. Thanks again. I will do it this way from now on.
    Jim

  7. #27

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    Another advantage of doing it this way is that you have better control of the staining properties. You want less stain, use 12% solution, you want more stain use 8% solution. I had to change my concentration when I moved to Mexico as the water here is very hard and was getting way more stain than I needed......

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