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  1. #1

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    Calgon™/Sodium hexametaphosphate

    I wanted to buy a box of Calgon™/Sodium hexametaphosphate, as mixing my developers, et cetera, is a bit of a problem, as our water is very hard. I have problems with a yucky sludge in my D-23, and whenever I mix hypo clearing agent, not all of the sodium sulfite will stay in solution. The box of Calgon™ I saw in our local supermarket had nothing on the side panel about containing sodium hexametaphosphate. Instead, it said, "...contains sodium sesquicarbonate and sodium tripolyphosphate..."

    Okay, I am obviously not a chemist; can anybody give me some information on this product? First, is it suitable for photographic use? Is it a viable substitute for sodium hexametaphosphate? Or is it just another way of referring to sodium hexametaphosphate? Is there another chemical which could be used, and will not cause the pH of my chemistry, especially my beloved D-23, to get tossed on its ear?

    Please, don't bother posting to advise me to get a water softener; that is not an option.

  2. #2
    Ian Grant's Avatar
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    Why not buy a cheap water filter instead, there's no point in adding extra chemicals when you don't need to. This will give you better water for rinsing the films too.

    Ian

  3. #3
    Wishy's Avatar
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    Why not just use distilled water instead? I don't think adding more chemicals will do the development process any good.

  4. #4
    Ian Grant's Avatar
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    Distilled water is relatively expensive, a small Britax type water filter produces very cheap use-able water.

    Ian

  5. #5
    Mike Wilde's Avatar
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    Canadian Calgon experience

    I live in a place where there is relatively soft water in the municipal supply.

    I found in a 'junk week' that someone had moved to town and then thrown out their reverse osmosis unit from when they had previously lived. It was crusted with iron and lime on the inlet filter, so it definitely did its job at the previous location.

    I rehabbed it , and have never been happier. Now I no longer have the need to lug distilled jugs home in the winter from the grocery store.

    when the water is of unknown qualtity I have used calgon, at a rate of 1g/l when processing E-6 away from home. (it was about 1/2 tsp as I recall).

    I have taken e-6 concentrates in the camper when off on car camping trips.

    After filtering and leaving lake water to settle, I boiled it on a camp stove, to drive off dissoved oxygen, then mixed the chems when the water cooled, after I had dissolved the calgon to keep anmy dissoved items in suspension.

    To temper the whole affair I would immerse all the bottles and tank (loaded in a changing bag) in a large wash tub that held lake water and heated on the camp stove water, to bring the whole affair to 100F. Timing was by way of wrist watch. Drying was by way of stove alcohol mixed in 20% with the final rinse - the film was dry in under 5 minutes, inside a camper with only me standing very still for that period of time.

  6. #6

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    I think I read somewhere that either Calgon is a different product in different countries or that its formulation had changed. Sorry I can't remember where I read it.

    Maybe a chemist could suggest an alternative chemical. Would EDTA-tetrasodium salt do it?

  7. #7
    Photo Engineer's Avatar
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    Calgon is now no longer Sodium Hexametaphosphate.

    Substitute 10 g/l of Disodium EDTA. You may have to adjust the pH of the final solution.

    PE

  8. #8

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    Quote Originally Posted by john_s View Post
    I think I read somewhere that either Calgon is a different product in different countries or that its formulation had changed. Sorry I can't remember where I read it.

    Maybe a chemist could suggest an alternative chemical. Would EDTA-tetrasodium salt do it?
    I'm an engineer, not a chemist, but according to the chemistry literature, Yes:

    EDTA refers to the chelating agent with the formula (HO2CCH2)

    Sodium Hexametaphosphate is used as a sequestering agent. It is used in the industry of soap, detergents, water treatment, metal finishing and plating, pulp and paper manufacture, synthesis of polymers, photographic products, textiles, scale removal and agriculture. sodium hexametaphosphate was the sequestrant in the original Calgon product. Phosphates have negative environmental impacts.

    sodium tripolyphosphate is a sequestrant

    disodium citrate is a sequestrant listed in a current Calgon MSDS

    Triethanolamine and Diethanolamine are sequestrants (Fe and Ca).
    Tom Hoskinson
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    Everything is analog - even digital :D

  9. #9
    Photo Engineer's Avatar
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    TEA and DEA are not very good sequestrants for hard water, and change the pH and buffer capacity.

    PE

  10. #10

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    Quote Originally Posted by Photo Engineer View Post
    TEA and DEA are not very good sequestrants for hard water, and change the pH and buffer capacity.

    PE
    Yes, TEA and DEA are best at gettering water and oxygen
    Tom Hoskinson
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    Everything is analog - even digital :D

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