pyrocat hd with metol - order of mixing

Discussion in 'B&W: Film, Paper, Chemistry' started by el wacho, Mar 8, 2008.

  1. el wacho

    el wacho Member

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    hi ,

    was going to start mixing this up when i started getting paranoid about the order it should be mixed! so... does the metol ( substituting for the phenidone ) go first?


    thanking you all in advance ...
     
  2. jim appleyard

    jim appleyard Member

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    Yes, metol goes first as it has a hard time dissolving in sulfite solutions.
     
  3. Jim Noel

    Jim Noel Member

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    To ease the dissolving of metol, first dissolve a pinch of sulfite, then the metol. Although metol does not dissolve easily in a sulfite solution, a small pinch helps it dissolve better than in plain water.
     
  4. jim appleyard

    jim appleyard Member

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    I may be wrong here, but I always thought that the reason for putting a pinch of sulfite in first was to absorb any O2 present in the water, thus making the metol last a bit longer. IMHO, metol will dissolve faster in plain water than it will in water with any sulfite.
     
  5. gainer

    gainer Subscriber

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    Pyrocat HD uses catechol, phenidone and sulfite.
    I think you will be happier if you make a batch of Pyrocat MC in glycol. I have to leave now.
     
  6. el wacho

    el wacho Member

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    love it! hit and run advice!

    i'm in australia and i'm not sure if we 've got glycol up here...


    why mc over hd mr pg ?
     
  7. snallan

    snallan Member

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    The metol and phenidone are more stable in non-aqueous solution. The glycol mentioned is propylene glycol (1,2-propanediol), which is used as a solvent in the food and pharmaceuticals industries, and a non-toxic anti-freeze.
     
  8. philsweeney

    philsweeney Member

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    Right or wrong I have always mixed the components in order as listed and never had any problems ever and I do use metol.

    Pyrocat-HD
    Stock Solution A
    Distilled Water 75 ml
    Sodium Metabisulfite 1.0 g
    Pyrocatechin 5.0 g
    Phenidone 0 .2 g*
    Potassium Bromide 0 .2 g
    Distilled water to make 100 ml

    Stock Solution B
    Distilled Water 70 ml
     
  9. Tom Kershaw

    Tom Kershaw Subscriber

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    Snallan,

    Do you get your propylene glycol from a publicly available source?

    Tom.
     
  10. snallan

    snallan Member

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    I have to admit, I use the water based HD version. Since Rayco closed their doors, I have found it difficult finding liquid chemicals from the normal suppliers.

    One who might be able to help is Fotospeed, but you will need to phone or email them for details, as they do not list raw chemicals online.

    On the other hand, I know aqueous solutions are less stable, but I am still using a batch of HD made last April and it is fine.
     
  11. gainer

    gainer Subscriber

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    I am ill, and I may not be making sense. The Pyrocat MC has no sulfite or bisulfite. The water solution is quite different from the glycol solution. Sulfite reduces the proportionality of the stain. You should search for Sandy King's posts about Pyrocat MC. I don't know why propylene gloycol should not be available in Australia. It is used in cosmetics, medicines for humans and other animals, as well as in safe antifreeze.
     
  12. Murray Kelly

    Murray Kelly Member

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    In Oz the antifreeze is ethylene glycol. Plus curious coloring agents. It would probably work just as well.

    Hope the dreaded lurgy is wearing off. I picked up a nasty head cold from the grandkids (who else?) and am not 100% myself.

    My biggest problem is to get the pyrocat here. I am doing a workaround since the XYL is going to alaska in Sep and hope to get supplies to her hotel in Vancouver during her brief stopovers.

    As for availablity of 'common' chems here, they make the stuff in industrial amounts but finding a seller of small quantities is something else again.

     
  13. Jim Noel

    Jim Noel Member

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    Propylene glycol is generally available at an RV supply store. It is used to prevent drinking water from freezing.
     
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  15. Bruce Osgood

    Bruce Osgood Membership Council Council

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    Surely you're not suggesting Propylene Glycol can be ingested? Are You? Can it?

    I thought it was used in place of, or in combination with water in machinery radiator systems to prevent freezing.
     
  16. sanking

    sanking Member

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    Mixing directions for Pyrocat-MC
    Courtesy of Gainer

    Stock A
    Propylene Glycol at 150F 750ml
    Pyrocatechin 50 g
    Metol 2.5g
    Ascorbic Acid 4.0g


    Mixing directions. Start with about 8ml of TEA at room temperature and a spoonful of water. Now add 2.5 g of metol and stir to make a slurry. This is eventually going to make a liter but you can start in a 1/4 liter cup. After the slurry gets a little more fluid, add 15-20 ml of some warm propylene glycol. Now you can transfer the metol slurry to the 750ml of warm propylene glycol and stir until dissolved. Now add 50 grams of pyrocatechin and stir until dissolved. Add 4.0g of ascorbic acid and stir until dissolved.

    Sandy King
     
  17. snallan

    snallan Member

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    While I would not drink it directly, it is used as a solvent in the food industry, and as a non-toxic anti-freeze in breweries and dairy establishments. (From personal experience.)

    "Taken internally, propylene glycol is harmless, probably because its oxidation yields pyruvic and acetic acids"
    Whitmore, Organic Chemistry (New York, 1951)​
     
  18. Bruce Osgood

    Bruce Osgood Membership Council Council

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    Geeeezzz, another lie my mother taught me: "You can't drink antifreeze, it'll kill you."
     
  19. Tom Hoskinson

    Tom Hoskinson Member

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    Bruce:There are several different chemicals used as antifreeze: Your mother was right about Methanol and Ethylene Glycol. Drinking Diethylene Glycol will make you very sick, but may not kill you.

    Here is an Ethylene Glycol Material Safety Data Sheet.

    http://www.jtbaker.com/msds/englishhtml/E5125.htm

    Here is a Diethylene Glycol Material Safety Data Sheet.

    http://www.sciencelab.com/xMSDS-Diethylene_glycol-9927514
     
  20. el wacho

    el wacho Member

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    sorry to interrupt ....

    to start with the metol first, do i prep the water with a pinch of sodium sulfite or use a pinch of the sodium metabisulphite?

    thanks.
     
  21. Tom Hoskinson

    Tom Hoskinson Member

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    Neither, I Agree with Pat Gainer and Sandy King - best to mix Pyrocat M-C following the Recipe Sandy posted. After you react the Metol and ascorbic acid with a small amount of TEA (Triethanolamine) and water, it all goes into solution quite easily.
     
  22. el wacho

    el wacho Member

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    ... sorry Tom,

    i meant for pyrocat hd...
     
  23. el wacho

    el wacho Member

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    and into water, not glycol.
    thanks
     
  24. snallan

    snallan Member

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    If you are going to dissolve the metol first, I would add a pinch of the sodium bisulphite to the water first, just to inhibit oxidation of the metol whilst dissolving it.

    I have never tried making the metol version of pyrocat HD. So cannot comment on whether the pyrocatechin already being dissolved, would make it easier to dissolve the metol, if added in the same order as for the phenidone.
     
  25. el wacho

    el wacho Member

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    thanks snallan
     
  26. el wacho

    el wacho Member

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    thanks all