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  1. #1
    gainer's Avatar
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    Useful stock solutions

    For what it is worth, it is handy to keep various chemicals in stock solutions as is done in most chemical laboratories. I'm keeping amidol, phenidone, ascorbic acid, pyrogallol, hydroquinone and catechiol in propylene glycol. The amidol and phenidone are in 1% solutions, 1 gram/ 100 ml, and the others are in 10% solutions. Amidol keeps in glycol solution, as does phenidone and the others. I can mix and match for experimental purposes, but it is convenient as well when I have become staid in my concoctions. (If that ever happens.)

    The chemicals that are dangerous, including amidol, pyro, catechol and hydroquinone, are also safer IMHO in the gkycol solution than in powder that can become airborne while measuring. Mixing once is better than mixing for each use. You can buy amidol 10 grams at a time to make a liter of solution. I have found amidol to be in some ways a good substitute for phenidone, but every time I open the container of dry powder, I worry. Of course, I can still spill the solution, but there's less chance of it getting into the air than the powder, especially when it is in glycol. Some of these things might be safer with the extra viscosity of glycerin instead of glycol.

    As usual, these materials dissolve easier in hot glycol, but it need not be as hot as I once thought.
    Gadget Gainer

  2. #2

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    Yes Pat, I dissolved my stock of amidol in propylene glycol about a year ago. It is still going strong.

    I have stock solutions of all my other developing agents as well. I didn't have any luck dissolving glycin in propylene glycol (or in other glycols and alcohols), but it dissolved just fine in TEA.
    Tom Hoskinson
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  3. #3
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    Help me with the math!

    Hi.

    As some of you might remember, a while back I screwed up, and ended up with 2lbs of Metol/hydroquinone mixed together. Since it's basically 1lb of Metal and 1lb of hydroquinone, the only problem comes from the fact that with mixed powders you can never be sure that any given measure of it is going to truly be 50/50.

    With this thought in mind I've been thinking, if I could mix them up into a stock solution I should be ok. After looking in the PLI the only formulas I found that use the same amount of the 2 are either DK-50 or DK60a (both actually very similar developers), both of which use Kodalk (sodium metaborate) as their alkali. If I'm remembering correctly (something I'm never really sure of), the pH of Kodalk and the pH of TEA are very close, so I was thinking that if I mixed up the 2 into some TEA that I could basically have a concentrated version of DK-50 (and LOTS of it!). The formula for DK-50 calls for 2.5g of metol and 2.5g of hydroquinone, and 10g of kodalk per liter so the question is: Into how much TEA would I need to dissolve the 2lbs of powdered chemicals I have here?

    The other chemicals in the DK-50 formula are potassium bromide 0.5g/l and sodium sulfite 30g/l and I know that kbr will dissolve into TEA, but will sodium sulfite? I'd probably just add the sodium sulfite when I mix up the working solution, simply because to add enough to make the formula correct would be expensive to buy at one shot. Along the same lines, how would using that formula without the sulfite at all work?

    I have a gallon of TEA here, would the 2 lbs dissolve into that? Or am I going to have to get more? Thanks for any help anyone can give me, I'm so confused over trying to figure it out that it's made my head spin!

    -Mike

  4. #4
    gainer's Avatar
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    Quote Originally Posted by MikeS
    Hi.

    As some of you might remember, a while back I screwed up, and ended up with 2lbs of Metol/hydroquinone mixed together. Since it's basically 1lb of Metal and 1lb of hydroquinone, the only problem comes from the fact that with mixed powders you can never be sure that any given measure of it is going to truly be 50/50.

    With this thought in mind I've been thinking, if I could mix them up into a stock solution I should be ok. After looking in the PLI the only formulas I found that use the same amount of the 2 are either DK-50 or DK60a (both actually very similar developers), both of which use Kodalk (sodium metaborate) as their alkali. If I'm remembering correctly (something I'm never really sure of), the pH of Kodalk and the pH of TEA are very close, so I was thinking that if I mixed up the 2 into some TEA that I could basically have a concentrated version of DK-50 (and LOTS of it!). The formula for DK-50 calls for 2.5g of metol and 2.5g of hydroquinone, and 10g of kodalk per liter so the question is: Into how much TEA would I need to dissolve the 2lbs of powdered chemicals I have here?

    The other chemicals in the DK-50 formula are potassium bromide 0.5g/l and sodium sulfite 30g/l and I know that kbr will dissolve into TEA, but will sodium sulfite? I'd probably just add the sodium sulfite when I mix up the working solution, simply because to add enough to make the formula correct would be expensive to buy at one shot. Along the same lines, how would using that formula without the sulfite at all work?

    I have a gallon of TEA here, would the 2 lbs dissolve into that? Or am I going to have to get more? Thanks for any help anyone can give me, I'm so confused over trying to figure it out that it's made my head spin!

    -Mike
    First off, you won't need the sulfite unless you plan on keeping a working solution for a long time. If you don't believe me, you can always add some sulfite directly to a working solution for comparison.

    You will be able to dissolve 1 lb of hydroquinone in a gallon, but chances are that not all the metol will dissolve. Whatever does dissolve will still make a fine developer. If TEA is the solvent, try diluting 1 part with 50 parts of water and using it about like you would D 76 1:1.
    Gadget Gainer

  5. #5
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    Quote Originally Posted by gainer
    First off, you won't need the sulfite unless you plan on keeping a working solution for a long time. If you don't believe me, you can always add some sulfite directly to a working solution for comparison.

    You will be able to dissolve 1 lb of hydroquinone in a gallon, but chances are that not all the metol will dissolve. Whatever does dissolve will still make a fine developer. If TEA is the solvent, try diluting 1 part with 50 parts of water and using it about like you would D 76 1:1.
    Well, I goofed a little. I tested my advice on a small scale with 10 grams each of M and Q and TEA to make 125 ml. The M and Q both dissolved and seem to be staying in solution as it cools. The solution is a clear, red-brown color. What I forgot is that for the maximum synergy between metol and hydroquinone, one needs a modicum of sulfite. Without it, MQ is a staining developer, and is much less active. You need add only 1/2 teaspoon of anhydrous sodium sulfite to 1 liter of the working solution make it act like D-76.

    One of the problems with TEA as the solvent is the viscosity of the cold solution. You may want to thin it somewhat with propylene glycol or keep it in a warm place.
    Gadget Gainer

  6. #6
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    Quote Originally Posted by gainer
    What I forgot is that for the maximum synergy between metol and hydroquinone, one needs a modicum of sulfite. Without it, MQ is a staining developer, and is much less active. You need add only 1/2 teaspoon of anhydrous sodium sulfite to 1 liter of the working solution make it act like D-76.
    Well, I would adding some Edwal Liquid Orthazite (which has sodium sulfite & benzotriazole, I believe it either IS the old BB Compound, or is very similar) to the working solution be good enough? If so, I figure the benzotriazole can basically replace the kbr in the DK-50 formula and everything should be fine.

    Quote Originally Posted by gainer
    One of the problems with TEA as the solvent is the viscosity of the cold solution. You may want to thin it somewhat with propylene glycol or keep it in a warm place.
    That hasn't been a problem so far, I keep it on a high shelf where the air is much warmer

    -Mike

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    I think I read somewhere that the sulphite in Orthazite is there to assist in the dissolution of the benzotriazole, and given that you don't need much benzotriazole, you would be adding a quite small amount compared to the amount of sulphite (usually) needed in a developer.

  8. #8
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    The amount of sulfite needed for synergism between metol and hydroquinone is not enough to produce fuzzy grain, and not even enough to produce coarse grain, but it is probably more than would be in an average dose of Orthazite. That 1/2 teaspoon amounts to about 3 grams per liter of working solution. I would lay off adding the Orthazite until you see if you really need it.
    Gadget Gainer

  9. #9
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    Quote Originally Posted by gainer
    First off, you won't need the sulfite unless you plan on keeping a working solution for a long time. If you don't believe me, you can always add some sulfite directly to a working solution for comparison.
    Ok, I understand that sulfite isn't needed, but in say the DK-50 formula, doesn't it do more than act as preservative?

    If I'm doing the math correctly, I now have a solution that is 12.5% Metol and 12.5% Hydroquinone, and if I'm also correct, to make a solution that has 2.5g/l of both chemicals (obviously it has to be both) I would add 20ml per liter, does that sound right? Thanks!

    -Mike

  10. #10
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    Quote Originally Posted by MikeS
    Ok, I understand that sulfite isn't needed, but in say the DK-50 formula, doesn't it do more than act as preservative?

    If I'm doing the math correctly, I now have a solution that is 12.5% Metol and 12.5% Hydroquinone, and if I'm also correct, to make a solution that has 2.5g/l of both chemicals (obviously it has to be both) I would add 20ml per liter, does that sound right? Thanks!

    -Mike
    Yes, that amounts to about 1+50. The role of sulfite in many developers is qualitatively known but not always quantitatively optimized. I know it may not seem that I did a lot of optimization, what with using teaspoons, but in fact, I have not found a sharp optimum for any one quality. Developer activity, sharpness, grain size, grain structure and in some cases staining properties all may be affected by sulfite content. In the case of MQ developers, no sulfite produces a staining developer. You may or may not like the color of the stain, but it is something you can play with. It takes very little sulfite to maximixe the activity and reduce or eliminate the stain. With a concentrated stock solution and one-shot working solution, preservation beyond, say, an hour is hardly ever required.

    At any rate, with the stock containing only M, Q and TEA, you have the flexibility of choice among working solutions with many different properties, some of which are mutually exclusive, but it will only take 20 ml of the stock solution to try each of them.

    I think you will find the variation of grain and gradation with change of sulfite content to be not what you might expect. Have fun.
    Gadget Gainer

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