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  1. #11
    gainer's Avatar
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    I'm not ready to condemn anyone else to what I did, at least not until I find out if it was worth it. I did some "let's see what happens" experiments with amidol and baking soda, amidol and carbonate and sure enough. these mixtures fizzed to beat the band. I never did see the precipitate I was expecting. Amidol sure makes a strong blue! Before I went to caustic soda I looked up some molecular weights. I figured 2 moles of NaOH to each mole of amidol and scaled it down to 10 grams of amidol and a little more than 8 grams of NaOH. I had a 50% NaOH solution, so I mixed 8 ml of that with the 10 grams of amidol. That was all the water I put in. I got a thick, very dark goo which could have been amidol base and sodium chloride. I'm not sure what else it could be. I added propylene glycol thinking maybe the salt would settle out. It was like trying to get something to settle out of cold Jello. Filter? Forget it. I started to heat it in the microwave to thin it out and immediately blew a fuse. I'm not even sure how to test it to see if it is the amidol base. If it develops film, it might be something else. Would the amidol base, dissolved in glycol, be blue? maybe its the stuff the Celts decorated themselves with before going into battle.
    Gadget Gainer

  2. #12

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    "Would the amidol base, dissolved in glycol, be blue?"

    Well, the amidol (2,4-diaminophenol dihydrochloride) that I've dissolved in glycol is certainly a very deep dark blue.

    Maybe you've done it, Pat.

    Then again, maybe you HAVE re-created Woad!
    Tom Hoskinson
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  3. #13
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    After much immature consideration I finally found the light. I think.

    Mixing amidol and NaOH in the right proportions gives NaCL, water and amidol base. The salt is of little concern because it will probably not dissolve in TEA or glycol, and if it did, the amount that would show up in the working solution is no greater than would show up in a water solution of amidol. The equation should look like this:

    197.07 grams amidol + 80 grams NaOH => 124.14 grams amidol base + 115.9 grams NaCl + 36 grams(ml) water.

    I took 10 grams of amidol and added 8.2 ml of my 50% NaOH (4.1 grams NaOH) and stirred the resulting sludge until the lumps were gone. I could see that extra water had appeared. Then I added TEA and 50 grams of pyrocat (i'm out of pyrogal) to make 500 ml. It dissolved with a little heating, enough to turn it from molasses in January to nice sugar syrup consistency.

    This is twice the concentration of pyrocatechol in Sandy's Pyrocat developers, IIRC. The result seems to be quite a powerful developer at 1+50 with no sulfite or additional alkali.

    There is some sediment at the bottom of the solution, which I would say is just NaCl. I don't think I would want to try to filter it out. I would decant what I want and make new when I get too close to the sediment. Perhaps with the proper filtering equipment it would be feasible.
    Gadget Gainer

  4. #14

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    What color was the mixture after you added the TEA and Pyrocat?

    And how about fog? Did the negatives have more fog than normal?

    Sandy

    Quote Originally Posted by gainer
    After much immature consideration I finally found the light. I think.

    Mixing amidol and NaOH in the right proportions gives NaCL, water and amidol base. The salt is of little concern because it will probably not dissolve in TEA or glycol, and if it did, the amount that would show up in the working solution is no greater than would show up in a water solution of amidol. The equation should look like this:

    197.07 grams amidol + 80 grams NaOH => 124.14 grams amidol base + 115.9 grams NaCl + 36 grams(ml) water.

    I took 10 grams of amidol and added 8.2 ml of my 50% NaOH (4.1 grams NaOH) and stirred the resulting sludge until the lumps were gone. I could see that extra water had appeared. Then I added TEA and 50 grams of pyrocat (i'm out of pyrogal) to make 500 ml. It dissolved with a little heating, enough to turn it from molasses in January to nice sugar syrup consistency.

    This is twice the concentration of pyrocatechol in Sandy's Pyrocat developers, IIRC. The result seems to be quite a powerful developer at 1+50 with no sulfite or additional alkali.

    There is some sediment at the bottom of the solution, which I would say is just NaCl. I don't think I would want to try to filter it out. I would decant what I want and make new when I get too close to the sediment. Perhaps with the proper filtering equipment it would be feasible.

  5. #15

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    I question the convenience of making an amidol stock solution if its only intended use is to make print developer. A typical print developer contains sulfite, amidol and potassium bromide. Since the sulfite will either be weighed out or measured by volume, why not measure the amidol in the same manner? You've already got the scale out, right. It's practical to use potassium bromide as a percentage solution because we are dealing with a small quantity. Not so for the amidol.

    The blue color may be due to a free radical. They typically display intense color. This would be even more likely if the color is discharged when the amidol solution is added to a sufite solution. BTW, the magenta coloration that simple Phenidone solutions take on is due to a free radical.

  6. #16

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    "I question the convenience of making an amidol stock solution if its only intended use is to make print developer."

    Minimizing (or eliminating) the exposure to amidol dust and vapor is one reason.
    Tom Hoskinson
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  7. #17

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    Quote Originally Posted by Tom Hoskinson
    "I question the convenience of making an amidol stock solution if its only intended use is to make print developer."

    Minimizing (or eliminating) the exposure to amidol dust and vapor is one reason.
    Amidol, being the dihydrochloride salt, does not have any significant vapor pressure. However, the dust could be a problem mainly from staining. The LD50 dose is rather high being 0.789 g/kg which means a 160 lb man would have to ingest 2 ounces. Amidol is therefore less toxic than Tylenol or asprin. Even if we consider long term exposure I would be more concerned with the two analgesics mentioned. Amidol is not currently considered to be carcinogenic and is used as an approved hair dye.

  8. #18
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    Aniline black is an approved hair dye, and I wouldn't consider ingesting any of it under any circumstances.

    We used to use quinone as green ink as well. I shudder when I consider the number of times I have spilled that on my hands as a child or smelled the distinctive odor of green ink.

    Gerald, can you cite a reference for that LD50? Thanks.

    PE

  9. #19

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    Gerald, considerable vapor (which manifests both as a respiratory irritant and a disagreeable odor) is released when I remove the (screw-on) lid from my amidol storage jar.

    This MSDS: http://physchem.ox.ac.uk/MSDS/DI/2,4...ochloride.html
    lists the following amidol Risks:

    R20 - Harmful by inhalation
    R21 - Harmful in contact with skin
    R22 - Harmful if swallowed
    R36 - Irritating to eyes
    R37 - Irritating to respiratory system
    R38 - Irritating to skin
    Tom Hoskinson
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  10. #20

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    Even if you forget about possible toxicity it is an annoying solid to handle. It is fluffy and sticks to things because of static charge.
    art is about managing compromise

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