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  1. #11
    Photo Engineer's Avatar
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    Quote Originally Posted by KenM View Post
    Formula?
    Photographers Formulary has it.

    PE

  2. #12
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    Quote Originally Posted by jnanian View Post
    bobby,

    add a pinch of sodium sulfite
    before you put elon/ metol in,
    it will change the water's ph
    and allow the metol to dissolve.



    john
    John is correct. This works and works very well!
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

  3. #13
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    Adding sulfte will prevent oxidation from taking place, and that is the reason for the pinch of sulfite. If you add sulfite to a package mix, you may have too much sulfite!

    Metol is an alkaline organic compound that is often sold as the sulfate salt. It is difficult to dissolve in alkali unless you make the acid salt which is the way Dektol is formulated.

    So, unless you scratch mix, don't add the sulfite.

    PE

  4. #14

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    Quote Originally Posted by Photo Engineer View Post

    Metol is an alkaline organic compound that is often sold as the sulfate salt. It is difficult to dissolve in alkali unless you make the acid salt which is the way Dektol is formulated.


    PE
    Which brings me back to the subject of stabilising agents used in developers compounded into a single-powder. I read somewhere that Kodak `Elon` is a particular very pure form of Metol and less likely to cause `Metol poisoning` than some less pure forms. How does this acid salt differ from regular Metol? I have read some of the patents for single-powder developers dating from mid 1940`s to early 1950`s, although I still don`t understand the function of Boric anhydride (Di-boron Trioxide) as a stabilising agent. Also, is the specially treated `Lithium hydroxide` used to boost the pH back to the desired level due to the inclusion of Boric anhydride?

  5. #15
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    I think lithium salts are used for the psycotherapy of photographers.

    Basically the developer is milled into small particles under nitrogen. The chemicals are protected by a variety of antioxidants to keep the developing agents and the sulfite from going bad. The alkali is in a separate particle from the developing agents and antioxidants in some mixtures, and so you see different types of granules in the mix. The hot water helps break down the granules.

    Early on, Metol had impurities, but I'm not sure of what all went on. Elon is or was, the purified salt of Metol made with sulfuric acid. It may be that Metol was offered as a sulfate as well, but I have not read this part of the history for years.

    In fact, the entire process for this has begun to fade badly. It has never really been documented anywhere outside of Kodak AFAIK with only minor references.

    PE

  6. #16

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    Sorry for the drift but I have always wanted to ask PE what are the two black specs that I have found over and over in Dektol packages? Is there some guy on the line counting them as added?

  7. #17

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    Quote Originally Posted by Photo Engineer View Post
    Basically the developer is milled into small particles under nitrogen. The chemicals are protected by a variety of antioxidants to keep the developing agents and the sulfite from going bad. The alkali is in a separate particle from the developing agents and antioxidants in some mixtures, and so you see different types of granules in the mix. The hot water helps break down the granules.

    In fact, the entire process for this has begun to fade badly. It has never really been documented anywhere outside of Kodak AFAIK with only minor references.

    PE
    The patents that I have read are rather dated, although it is a subject that fascinates me. With raw chemicals, it is recommended that Metol is dissolved before the Sulphite which is where the inclusion of the Elon mixed with the rest of the components in one powder interest me. I am not quite sure of the Boric anhydride though after reading the section of Borate Alkali`s on page 244 of Grant Haist`s book.
    MSDS for Kodak developers I found here: http://www.kodak.com/eknec/PageQueri...equestid=11047

    Ethol UFG, LPD and Acufine are also single mix developers, so not exclusive to Kodak.

  8. #18
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    Quote Originally Posted by vet173 View Post
    Sorry for the drift but I have always wanted to ask PE what are the two black specs that I have found over and over in Dektol packages? Is there some guy on the line counting them as added?
    I have no idea what you are talking about. Maybe they are 'getters' for anything that can oxidize the developer. IDK.

    I could give you the name and address of the head of Powders and Solutions at Kodak, but he left and entered the ministry.

    PE

  9. #19
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    Quote Originally Posted by Keith Tapscott. View Post
    The patents that I have read are rather dated, although it is a subject that fascinates me. With raw chemicals, it is recommended that Metol is dissolved before the Sulphite which is where the inclusion of the Elon mixed with the rest of the components in one powder interest me. I am not quite sure of the Boric anhydride though after reading the section of Borate Alkali`s on page 244 of Grant Haist`s book.
    MSDS for Kodak developers I found here: http://www.kodak.com/eknec/PageQueri...equestid=11047

    Ethol UFG, LPD and Acufine are also single mix developers, so not exclusive to Kodak.
    This is gonna be hard to do, but here goes....

    Hydroquinone is HO-Phenyl-OH
    Metol is CH3-NH-Phenyl-OH
    Elon used in Dektol is (CH3-NH-Phenyl-OH)^+2 and H2SO4. There are 2 metols for every sulfuric acid and so you have (CH3-NH2^+ -Phenyl-OH)2 and SO4^= (the ^ denotes superscripting)

    This means that Metol is both an acid and a base, but the base form is very subject to reaction with air, and so it is made into a salt of sulfuric acid where two Metols react with one sulfuric acid. This is the "Bis" in the MSDS. It means two of them are associated with each sulfuric acid.

    Now, when you hit base.... You get salts of these as follows:

    HQ is Na-O-Phenyl-O-Na where phenyl has two negative charges on the HQ oxygens.

    Elon is now CH3-NH-Phenyl-O-Na with one negative charge on the oxygen. The sodium ions are positive.

    Has this confused you enough yet? We still have oxidation products to go and sulfonation of the HQ. But I think you see that there is a lot involved in this simple mixture that must be protected from air and water in the package until it gets to you.

    PE

  10. #20

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    Quote Originally Posted by Photo Engineer View Post
    This is gonna be hard to do, but here goes....

    Hydroquinone is HO-Phenyl-OH
    Metol is CH3-NH-Phenyl-OH
    Elon used in Dektol is (CH3-NH-Phenyl-OH)^+2 and H2SO4. There are 2 metols for every sulfuric acid and so you have (CH3-NH2^+ -Phenyl-OH)2 and SO4^= (the ^ denotes superscripting)

    This means that Metol is both an acid and a base, but the base form is very subject to reaction with air, and so it is made into a salt of sulfuric acid where two Metols react with one sulfuric acid. This is the "Bis" in the MSDS. It means two of them are associated with each sulfuric acid.

    Now, when you hit base.... You get salts of these as follows:

    HQ is Na-O-Phenyl-O-Na where phenyl has two negative charges on the HQ oxygens.

    Elon is now CH3-NH-Phenyl-O-Na with one negative charge on the oxygen. The sodium ions are positive.

    Has this confused you enough yet? We still have oxidation products to go and sulfonation of the HQ. But I think you see that there is a lot involved in this simple mixture that must be protected from air and water in the package until it gets to you.

    PE
    Confused and intrigued, thanks.

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