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Thread: bad phenidone?

  1. #1

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    bad phenidone?

    Just last week I received a new supply of Phenidone and I mixed up a fresh batch of PC-TEA. My last batch of PC-TEA, mixed with my four years old supply of phenidone gave me a B+F of around .12 with FP-4+, with the new phenidone my freshly mixed PC-TEA gave a B+F of about .50 (!) and about 1 1/2 stops less film speed. Thinking I goofed somehow, I mixed another, smaller batch of PC-TEA. Same thing.

    From there I made simple PQ/carbonate developer, which normally would give me a B+F of around .16. I haven't measured the B+F yet but it is obviously way too high and the film speed too slow. I'm positive the HQ is good so that kind of narrows the problem down to the phenidone. As a reality check I mixed up a simple metol formula and this came out normal.

    Anybody have any ideas or should I just write this off as a bad batch of phenidone?

  2. #2

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    Impossible to say what the problem is. However, my experience is that phenidone has a very long shelf life, even when stored in partially full bottles at room temperature. I have a stock that is more than ten years old and it is still working fine.

    Perhaps you made a mistake in measurement and put more phenidone in the solution than required. The could explain the high B+f.

    Sandy King



    Quote Originally Posted by ajduran View Post
    Just last week I received a new supply of Phenidone and I mixed up a fresh batch of PC-TEA. My last batch of PC-TEA, mixed with my four years old supply of phenidone gave me a B+F of around .12 with FP-4+, with the new phenidone my freshly mixed PC-TEA gave a B+F of about .50 (!) and about 1 1/2 stops less film speed. Thinking I goofed somehow, I mixed another, smaller batch of PC-TEA. Same thing.

    From there I made simple PQ/carbonate developer, which normally would give me a B+F of around .16. I haven't measured the B+F yet but it is obviously way too high and the film speed too slow. I'm positive the HQ is good so that kind of narrows the problem down to the phenidone. As a reality check I mixed up a simple metol formula and this came out normal.

    Anybody have any ideas or should I just write this off as a bad batch of phenidone?

  3. #3

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    Thanks for your input Sandy.

    I thought too much phenidone was a possibility, but I weighed it three separate times and mixed three different stock solutions so I'm doubtful that is the case here. The phenidone is fresh, by the way, I just received a new batch which is why I'm suspicious. I'm pretty sure my equipment is not contaminated because the metol developer worked fine. Too bad I don't have any of the old phenidone left to cross check. Well, I may just experiment a little with decreasing the amount anyway to see what happens before I go ahead and order a new batch.

  4. #4
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    I read that phenidone turns red when oxidized beyond repair. Like Sandy, I had some that was 10 or more years old and still working when I used it up.

    Another possibility is that some other compound was supplied by mistake. The typical phenidone acts like talc when you put it in water. It doesn't want to get wet. It is soluble in glycerine, glycol and alcohol.

    There must be something wrong if the powder is white or light yellow and will fog film but not develop it.
    Gadget Gainer

  5. #5
    Ian Grant's Avatar
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    I only finished my original batch of Phenidone 2 or 3 years ago, it was made in 1961, I bought a large quantity of it in the mid 70's. It keeps very well and there was no loss in quality over the years I used it.

    It's possible you have been sold contaminated Phenidone, or one of your other chemicals is causing the problems.

    Ian

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    It should also be noted that very little phenidone is needed in film developers. Typically phenidone is used in place of metol at ratios of 1:10 to 1:20. A liter of Stock Solution A of Pyrocat-HD only contains two grams of phenidone, and even that amount might be slightly in excess. One could easily make a measuring error that would make a developer very energetic but low contrasat.

    Sandy King

  7. #7

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    I should have pointed out contrast was normal but fog very high and film speed at least 1 stop slower than normal. The phenidone in question looks and acts like phenidone: white, fluffy, takes a while to get wet. It does have some hard chunks. I don't know if this is significant. My old batch of phenidone was mostly powder, some clumps but not hard chunks like this stuff.

    I tried again using 1/2 the amount of phenidone. Fog is normal, contrast normal, but film speed still about 1 stop too slow. I use an X-Rite 303 sensitometer and X-Rite 810 densitometer to check for speed/contrast whenever I mix a new batch of developer so I'm pretty sure my data is accurate. I also cross checked the gunpowder scale I use to weigh phenidone against my Acculab VI-400. I'm confident I'm weighing the phenidone to a degree of accuracy beyond what is required.

    I don't know what's wrong but at this point I've used more film testing this than the phenidone is worth. I'll probably just order another batch from a different source and set this stuff aside. At 1/2 normal qty I think it should work just fine for paper developers.

    Thanks to everybody who responded though, I appreciate your input.



 

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