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  1. #1

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    Dimezone-S instead of phenidone in Pyrocat-HD?

    I have acquired some Dimezone-S which is reputed to be a better-keeping variety of phenidone. I'm interested in knowing if anyone has tried it, and if so any advice about equivalent quantities. Someone on the old pure-silver list suggested that I substitute equivalent molar weights (i.e. multiply the recipe's amount of phenidone by about 1.15). He had also done some tests in a very different developer to compare the two versions and found that this conversion worked for him.

    Leaving aside the potential for weighing inaccuracy with comparatively small amounts of this chemical, how critical is the amount of phenidone in Pyrocat-HD?

    The reason I'm trying this is because I'm using the metol version of Pyrocat-HD since my first attempt with phenidone didn't work at all well. Maybe that batch of phenidone was bad, since all the other ingredients worked very well in the metol batch that I mixed up. The metol version is great, but a little more speed would always come in handy!

  2. #2

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    Quote Originally Posted by john_s
    I have acquired some Dimezone-S which is reputed to be a better-keeping variety of phenidone. I'm interested in knowing if anyone has tried it, and if so any advice about equivalent quantities. Someone on the old pure-silver list suggested that I substitute equivalent molar weights (i.e. multiply the recipe's amount of phenidone by about 1.15). He had also done some tests in a very different developer to compare the two versions and found that this conversion worked for him.

    Leaving aside the potential for weighing inaccuracy with comparatively small amounts of this chemical, how critical is the amount of phenidone in Pyrocat-HD?

    The reason I'm trying this is because I'm using the metol version of Pyrocat-HD since my first attempt with phenidone didn't work at all well. Maybe that batch of phenidone was bad, since all the other ingredients worked very well in the metol batch that I mixed up. The metol version is great, but a little more speed would always come in handy!
    John, I dont know who you got the phenidone from, but you must have had a bad batch. I bought 50 gr of phenidone 3 years ago, I have kept it dry and in a dark place and it is still as good as the day I got it.

    As to your question, beats me, why dont you try and tell us how it went.

  3. #3

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    I have substituted Phenidone 1:1 (in a Suzuki formulation) for Dimezone-S and had good results.

    The Phenidone I used is around 30 years old, by the way - no change in activity that I can notice. I keep it dry, sealed amber glass container.
    Tom Hoskinson
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  4. #4

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    Quote Originally Posted by john_s
    Leaving aside the potential for weighing inaccuracy with comparatively small amounts of this chemical, how critical is the amount of phenidone in Pyrocat-HD?
    The amount of phenidone in the Pyrocat-HD formula is not as critical as one might think. In my own tests I have seen very little difference with amounts ranging from 1.5 g per liter to 2.5 g per liter of Stock Solution A. The minimum amount appears to be about 1.0 g, and the maximum about 3.0. Below 1.0 g there is not as much synergism (= longer development times) and above 3.0 g there is an increase in B+F.

    I have no experience with Dimezone-S. However, as others have suggsted, phenidone in powder form lasts a very long time. And once mixed in the Pyrocat-HD stock solution the useful life is at least six months in a partially full bottle. And if you need more shelf life out of the Stock Solution A consider mixing it in propylene glycol instead of water, which should increase its life to years instead of months.

    Sandy

  5. #5

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    Where do you guys get Dimezone-S?

  6. #6

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    Quote Originally Posted by psvensson
    Where do you guys get Dimezone-S?
    I have never purchased or used it. I use regular phenidone and am quite happy with it.

    However: http://www.techcheminc.com/Photo_Order.htm
    advertises it ( and other photo chemicals) for sale in small quantities:

    Dimezone - S 4-Hydroxymethyl-4-Methyl-1-Phenyl-3-Pyrazolidone
    DZ00100 100 grams $ 34.64
    DZ01001 1 lb $125.79
    Tom Hoskinson
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  7. #7

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    Very cool, thanks. Didn't know about Tech Chem. Apart from better keeping qualities, I thought one of the advantages of Dimezone was that it dissolves easier in water?

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    Easier dissolution was one reason I wanted to try it. I'm in Australia, and have found that Sigma-Aldrich, the big chemical company, has stopped listing it. I enquired with an English company which has a local agent. Normally the minimum package size is 25kg (enough for 12500 Litres of Pyrocat-HD stock, enough for 2,500,000 films)

    I was lucky to enquire just when one customer was taking delivery of 25kg, and they arranged for me to take 1kg. Who in Australia would want 25kg of it? I don't know, but maybe it's used for colour processing of some type, perhaps reversal.

    I'll let you know how it goes.

    Incidentally, my failed attempt with phenidone involved my use of a stock solution of phenidone in ethyl alcohol (95% food grade) so maybe something went wrong with the stock. It was only a few days old, though.

  9. #9

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    Quote Originally Posted by john_s
    Easier dissolution was one reason I wanted to try it. I'm in Australia, and have found that Sigma-Aldrich, the big chemical company, has stopped listing it. I enquired with an English company which has a local agent. Normally the minimum package size is 25kg (enough for 12500 Litres of Pyrocat-HD stock, enough for 2,500,000 films)

    I was lucky to enquire just when one customer was taking delivery of 25kg, and they arranged for me to take 1kg. Who in Australia would want 25kg of it? I don't know, but maybe it's used for colour processing of some type, perhaps reversal.

    I'll let you know how it goes.

    Incidentally, my failed attempt with phenidone involved my use of a stock solution of phenidone in ethyl alcohol (95% food grade) so maybe something went wrong with the stock. It was only a few days old, though.
    Most likely that was your problem, once diluted, even in alcohol, phenidone goes bad pretty quick. BTW, why dont you try Artcraftchemicals in the US? Michael ships to me in Mexico and he always does an excellent job. It might be cheaper even with the shipping than buying 25 Kg. No?

  10. #10

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    Quote Originally Posted by psvensson
    Very cool, thanks. Didn't know about Tech Chem. Apart from better keeping qualities, I thought one of the advantages of Dimezone was that it dissolves easier in water?
    Suzuki implies that Dimezone-S is easier to dissolve in water than Phenidone. I have no problem dissolving Phenidone in water if I first dissolve it in a small amount of alcohol. This should be done as an integral part of a developer mixing sequence. Pyrocat-HD "A" solution, prepared this way, will last for months.

    An alcohol or alcohol/water Phenidone stock solution will start oxidizing almost immediately - with no appreciable color change.

    To prepare a stable Phenidone stock solution, dissolve the Phenidone in propylene glycol.
    Tom Hoskinson
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    Everything is analog - even digital :D

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