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  1. #1
    gainer's Avatar
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    Rodinal-like developer from Metol

    Mix 40 grams of Metol with 15 grams of sodium sulfite in 1 liter of water. Add 19 grams of sodium hydroxide. Filter, saving the contents of the filter paper. That which passes through the filter is mostly sodium sulfite and sodium sulfate. That which remains is mostly the Metol base. Mix the contents of the filter paper with 750 ml of water and add 85 grams of sodium sulfite. Stir vigorously while adding 19 grams of sodium hydroxide. All or nearly all of the precipitate will dissolve. Bring the volume up to 1 liter. Use as you would Rodinal.

    The result is a solution of a sodium salt of the Metol base and sodium sulfite.

    I also made a batch in which I mixed the 85 grams of sulfite, 40 grams of Metol and 38 grams of hydroxide to make a liter which included the sulfate formed from the H2SO4 of the Metol. It is a little darker in color, but I haven't seen a difference in performance. Sodium sulfate is sometimes used in tropical developers to slow the reaction and minimize swelling of the emulsion, but the amount created here is probably not enough to do that job.
    Gadget Gainer

  2. #41
    gainer's Avatar
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    I think the precipitation occurs when the metol base is formed, when just enough hydroxide is added to form the nearly insoluble base, but not yet enough to form the soluble salt, just as happens when we make Rodinal. If we add the total calculated amount of hydroxide, the change from soluble to insoluble and back to soluble occurs continuously and so is not noticed.
    Gadget Gainer

  3. #42

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    If you see how much coast a bottle of Rodinal, I have some problems to find out my interest to do it by myself.
    The development of my films takes me already enough time.
    But it is nice to know that we can produce the Rodinal by ourself the day I won't find it any more on the market.
    "Le Noir&Blanc dépouille la réalité d'une coquetterie dont elle n'a pas besoin pour émouvoir." J.G. Blanchard
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    analog-photo.com

  4. #43

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    I just tested my Metolal stored in a 1/3 full sealed glass bottle for 28 months.
    It seems not to work anymore,blank film.I tried adding more sodium hydroxide but this did not revive it, failure was not due to atmospheric CO2 reacting with hydroxide in the original mix.
    I wonder if the sulfite content of the concentrate could be increased.
    (1) Crawley (BJP Jan 6 1961) found sodium sulfite at 5g/L in the working solution is best with Metol as developing agent,it removes the oxidation products.
    (2) More sulfite might be a better preservative if oxidation was the cause of the failure.
    To get 5g/L at 1:50 dilution means 250g/L sulfite in the concentrate.
    This is close to the solubility I looked up 270g/L.
    I wonder if there is any opinion on increasing the sodium sulfite in the concentrate.

  5. #44
    Ian Grant's Avatar
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    The opening words give the game away.

    A 1/3 full bottle has enough oxygen present to allow the Metol to oxidise over that period of time.

    Rodinal & R09 use slightly more Sulphite than Crawley suggest but as the more souble Potassium form

    Ian

  6. #45

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    It seems quite likely the shelf life of this developer could be increased by keeping it in two parts,a lower pH one with metol and sulfite and one with sodium hydroxide.
    It would end up something like FX-1 or Beutler with a hydroxide part B,something not tried very much.

  7. #46

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    Regarding oxidation: When I did my own processing... long ago... I used glass marbles to take up volume thereby displacing air space.

  8. #47
    Philippe-Georges's Avatar
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    Shelf life?
    Who is afraid of the Rodinal Wolf...
    "...If you can not stand the rustle of the leafs, then do not go in to the woods..."
    (freely translated quote by Guido Gezelle)

    PS: English is only my third language, please do forgive me my sloppy grammar...

  9. #48

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    To my failed Metolal I added enough metol to make the original concentration 40g/L.The metol appears slightly acidic and I had to add some sodium hydroxide to the 1:50 working solution to increase the pH from ~9 to ~11.
    The metol addition restored the developing activity of the failed Metolal and I successfully developed a test film in the working solution at pH 11.
    Thus,in the failed Metolal,it was the metol that failed not the sulfite or hydroxide.In Rodinal, p-aminophenol would not be expected to fail so rapidly IMO.
    Only one experiment but it does suggest that metol undergoes some oxidation or hydrolysis to which p-aminophenol is not susceptible.

  10. #49
    Ian Grant's Avatar
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    We are touching on this in the Modern alternatives to Rodinal thread.

    There are good reasons why Afgfa, Ilford Kodak, Johnsons etc went down the p-Aminophenol route. Most of the early research is probably lost unfortunately.

    Ian

  11. #50

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    Quote Originally Posted by gainer View Post
    I have had an attack of viral encephalitis and a computer brain failure since then, so I calculated that for every molecular weight of Metol there should be 4 molecular weights of hydroxide, which could of course be either sodium or potassium. 2 moles are used to change the H2SO4 to Na2SO4 and 2 more to create the sodium salt of Metol.
    Metol MW is 344.38, MW of NaOH is 40, so 40g of Metol = 0.114M and we need 4*0.116*40 = 18.584g of NaOH for create Metol.base.Na2 salt ((C7H10NO)2.Na2). now we can rewrite Metolal formula as:

    Sodium Sulfite 85g
    Metol 40g + NaOH 18.584g = 34.18g of Metol.base.Na2 salt
    NaOH 38-18.584=19.416g
    Water 1l

    i.e. we have 19.4g of free NaOH in concentrate!
    I think that this formula is very different from EZRodinal where concentrate haven't any free of NaOH. When we dilute Metotal 1:50 we have:

    Sodium Sulfite 1.7g
    Metol.base.Na2 salt 0.68g
    NaOH 0.4g
    Water 1l

    I know only one receipt like this. Here is the link (russian) and here is translation to english. receipt is simple:

    20ml of D23 stock
    12ml of 20% solution of NaOH
    Water to 300ml

    recalculate to 1l of all components:

    Sodium Sulfite 6g
    Metol 0.45g
    NaOH 7.2g
    Water 1l

    this is equivalent to

    Sodium Sulfite 6g
    Metol 0.45g + NaOH 0.2g = 0.385g of Metol.base.Na2 salt
    NaOH 7g
    Water 1l

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