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  1. #101

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    Quote Originally Posted by Photo Engineer View Post
    As for the other new ingredients? Well, did you get the secret ingredient of the other developer that you are interested in? Mine are very common in several cases and are actually in use in some developer, just not in combination or proper combination.
    I searched through the patents, and here are the silver halide complexing agents I noticed which could be considered organic (containing carbon):

    Thiourea (an "organosulfur") (plus Phenyl-, Allyl-, Ethylene-)
    Sodium/potassium/ammonium Thiocyanate
    3,6-Dithia-1,8-octanediol (CAS 5244-34-8) (many others in this family, but nobody's selling them)
    ethylene-bis-thioglycolic acid (or GDMA) (CAS 123-81-9) (many others in this family, but nobody's selling them)

    Thiourea came up repeatedly. Other searching shows it to be a powerful solvent (only .5-1 g/L needed). Are there any disadvantages to this, such as skin contact dermatisis mentioned in an MSDS? I'm hoping it'll dissolve in PG.
    The Thiocyantes also are common. They contain carbon, but that doesn't mean they'll dissolve in PG, as I found out with Sodium bicarbonate. Comments about Thiocyanates?
    How strong a solvent are 3,6-Dithia... and ethylene-bis-...? The 3,6 is easily purchasable for about $33 for 25g, so it's tempting if it's a strong solvent and PG-soluble and not too toxic.

    Sorry about so many questions in one post. I'm learning.
    Thanks!

    Mark Overton

  2. #102

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    Several more compounds are listed in Grant Haist's book "The Monobath Manual." Anyone interested in photographic chemistry should have this book as it contains quite a bit of information for its size.

    Ionic compounds such as sodium bicarbonate are not usually soluble in non-ionic solvents such as glycols. Kodak uses a mixture of TEA and DEA to provide the proper pH for HC-110. They also use the addition product of DEA and sulfur dioxide to replace sodium sulfite used in conventional water based developers.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  3. #103
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    Mark;

    You are looking in the wrong places. You want developer stabilizers, not silver halide solvents! At least in this context. As for silver halide solvents, you just have to experiment as the level is very much a function of the developer formulation itself. This is grinding plodding work that involves the use of what is called a factorial experiment.

    PE

  4. #104

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    Jerry:
    Thanks for the book recommendation. I just received Mees, and I'll try to find this one as well.

    Quote Originally Posted by Photo Engineer View Post
    You are looking in the wrong places. You want developer stabilizers, not silver halide solvents! At least in this context. As for silver halide solvents, you just have to experiment as the level is very much a function of the developer formulation itself. This is grinding plodding work that involves the use of what is called a factorial experiment.
    DS-10 and XTOL get some of their fine grain from the solvent-effect of Sodium Sulfite, and we need a substitute for Sodium Sulfite that'll dissolve in Propylene Glycol. That's why I was looking at solvents. I thought that stabilizers didn't remove any silver halide, but merely rendered it unexposable, -or- improved the keeping qualities of an emulsion. Or do I have that wrong? (wouldn't be the first time).

    Mark

  5. #105

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    Regarding solvents,you need to check the availability and safety aspects but I believe diethanolamine bisulfite may suit.
    http://www.freestylephoto.biz/pdf/ms...FOTEC_LC29.PDF
    Thiocyanate used to be used in Kodak DK20, see the Film Developing Cookbook p65, but appears to have found a new lease of life in Spur formulation, perhaps they solved some problems by advanced methods not generally known.I doubt it will dissolve in propylene glycol or TEA.
    This is very advanced stuff if you just started to experiment.

  6. #106
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    Mark, there are emulsion stabilizers and developer stabilizers. There are even fix stabilizers! Sulfite does this job in all 3 cases but works by different methods in some cases. There are examples of all 3 types in my published work. The problem is that you are trying to fly before you can walk and that will take a bit of time. As Alan says, this is advanced stuff!

    PE

  7. #107

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    Haist mentions the amino acid cysteine as a silver halide solvent. I know that the amino acid arginine is also a silver halide solvent as it interferes with the classical analysis for chloride with Ag+. Both are available in health food stores as a powder at reasonable prices. They should be soluble in glycols. Cysteine contains a thiol (-SH) group along with many other chemicals which accounts for the halide solvency. Arginine has several amine groups which accounts for its solvency affect. Of the two mentioned cysteine is probsbly better as a first choice.
    Last edited by Gerald C Koch; 12-21-2011 at 05:12 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

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  8. #108
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    There's mention of Haist's Monobath book but some of the Russian work is rather interesting and perhaps more advanced. I think it was Neville Maude who wrote an article which went a few steps further. I did scan it a few years ago and posted here (on APUG) but it may have been lost like many articles/formulae in updates to the site.

    Alan Johnson is right in saying that devs like DK20 went out of use, as newer emulsions in the 1960's suffered dichoic fogging (my comment), but emulsions have changed again and these avenues are used again but with newer formulations.

    Another well known person (think backwards) claims that Phenidone versions of MQ paper developerformulae are colder toned. when the exact opposite is true.

    So the question is who/what do you believe or trust as films/emulsions change and comments made in the poast may no longer be apt.

    Ian

  9. #109
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    I would have to look this up and perhaps it is in Haist, but some amino acids will severely reticulate film. Be very careful when you try to use them in tests as you may damage your film. I remember doing so many years ago! Sorry I cannot remember which one(s) do so.

    PE

  10. #110

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    Quote Originally Posted by Photo Engineer View Post
    I would have to look this up and perhaps it is in Haist, but some amino acids will severely reticulate film. Be very careful when you try to use them in tests as you may damage your film. I remember doing so many years ago! Sorry I cannot remember which one(s) do so.
    That's no problem. I'll just name the developer "Reticulon".
    Seriously, you are right about learning to walk first. I've realized that my knowledge of chemistry is badly rusty after decades of disuse, and that I need to buy a good college freshman level book and read-up.

    Alan: Regarding diethanolamine bisulfite, that's a compound of DEA? DEA itself is a solvent, although in another posting, PE indirectly says it's probably a bit weaker than sulfite. Would the bisulfite-version be a stronger solvent?

    Gerry: Thanks for the suggestions, and I'll look at the health food store for those amino acids, especially cysteine. Would any cysteine-compound suffice, or must it be cysteine-HCl?

    Here's a formula that I'm thinking of mixing up and using as a basis of experimentation:


    Propylene glycol .............. 48 ml (adjust so result is 50 ml. or 100 ml if too viscous)
    Ascorbic acid ................. 10.7 g (alternate: Sodium ascorbate 12g)
    Sodium metaborate ......... >=8 g (4g to convert ascorbic, + 4g for XTOL)
    Boric acid ...................... ?? g
    Phenidone ..................... 0.15 g
    Makes 1 litre of working solution. The intention is that the metaborate would react with the ascorbic acid in situ, creating the 12g of ascorbate specified in the XTOL-patent. Other byproducts concern me, especially H2O. The remaining metaborate would be the alkali and form a buffer with the boric acid. The boric and/or metaborate would be adjusted to give a pH of 8.2, making this similar to XTOL but with no halide-solvent. And then would come the fun part of trying halide-solvents and probably tweaking other things. As always, comments about all this are welcome.

    Mark Overton



 

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