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  1. #51

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    Quote Originally Posted by P C Headland View Post
    Given you want Xtol quality with near HC110 convenience, you may want to mix up a small batch of PC-TEA. You'll have the ingredients to hand.
    My admittedly limited experience led me to thinking of PC-TEA as like a cross between Xtol and Rodinal, taking the best (for me) features of each. My more experienced friend likened it to the best of Xtol and HC110.
    Have fun with the experiments.
    Thanks for the suggestion. Coincidentally, the TEA arrived in the mail today, so you can guess what I'll be doing this weekend.
    A few postings in apug.org have noted that PC-TEA is a little grainier than XTOL, probably due to having no solvent in the soup. Adding Sodium Sulfite creates Jordan's "Instant Mytol", described here: http://www.apug.org/forums/forum223/...ant-mytol.html
    So I'm thinking of trying some of that Instant Mytol.

    Mark Overton

  2. #52

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    Regarding not storing DS-10 for more than two weeks:

    Quote Originally Posted by Gerald C Koch View Post
    I think that Ryuji was being conservative at this point because he hadn't finished testing for the developer's storage life. The Stability Constant for the iron-salicylate complex is 6.55 which I think is adequate.
    I found a quote by Ryuji where he says that "DS-10 is a very good fine grain film developer, but it should not be kept for more than a couple of weeks, as I've seen cases where developer went off after that period." Here's the link: http://www.apug.org/forums/forum37/1...developer.html

    He doesn't say under what conditions it went off. Perhaps it would last longer if kept cool and air in bottles displaced with inert gas. Gerald reports having no problems after a month.

    Mark Overton

  3. #53

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    The good thing about PC-TEA is that it seems to have keeping qualities more akin to Rodinal / HC110 than Xtol. Like Rodinal, it darkens once opened, but it's activity seems to stay the same. I'm still working my way through a batch I made almost 5 years ago.

  4. #54

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    Quote Originally Posted by P C Headland View Post
    The good thing about PC-TEA is that it seems to have keeping qualities more akin to Rodinal / HC110 than Xtol. Like Rodinal, it darkens once opened, but it's activity seems to stay the same. I'm still working my way through a batch I made almost 5 years ago.
    PC-TEA has little developer in it, so to keep dev-times reasonable, the pH is high. But that boosts fog, and makes grain worse (compared to XTOL or DS-10). But I like the convenience of PC-TEA, and its longevity. Thanks for pointing out the nearly 5-year life you've gotten out of it. Such results are valuable knowledge. Do you know if PC-Glycol has similar longevity?

    My approach will be to mix some Instant MYTOL -- organic solution, invented by Jordan and disclosed here: http://www.apug.org/forums/forum223/...ant-mytol.html
    It has all the chemicals (except sulfite) mixed in TEA and propylene glycol. The sulfite is mixed into the working solution separately, so it's not as convenient as PC-TEA, but it's still convenient enough, and the concentrate should last years.

    After testing that, I'll try changing the quantities of its developers to match DS-10, and adjust alkali to hit the DS-10 target pH of 8.0.

    BTW, I tried mixing sulfite into propylene glycol as a suspension (it won't dissolve), but the sulfite granules are too large and heavy, and sink too quickly for the suspension to be of any use. Also, the sulfite sediment tends to self-glue as a single hard chunk on the bottom, so even a finely ground suspension will probably fail. That means we mix the sulfite separately. Oh well.

    Mark Overton
    Last edited by albada; 12-03-2011 at 10:33 PM. Click to view previous post history. Reason: Improve clarity

  5. #55

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    Quote Originally Posted by albada View Post
    BTW, I tried mixing sulfite into propylene glycol as a suspension (it won't dissolve), but the sulfite granules are too large and heavy, and sink too quickly for the suspension to be of any use. Also, the sulfite sediment tends to self-glue as a single hard chunk on the bottom, so even a finely ground suspension will probably fail. That means we mix the sulfite separately. Oh well.

    Mark Overton
    Inorganic compounds like sodium sulfite are not usually soluble in organic solvents. Kodak when formulating HC-110 (which contains no water) had to use an organic adduct of an amine and sulfur dioxide in order to get sulfite into the developer. They did the same for bromide using an adduct with hydrogen bromide.

    When mixing up a concentrate with TEA or glycols be sure not to get the mixture too hot. Doing so causes some oxidation of the developing agents and results in a dark color. Actually everything will eventually dissolve at room temperature, you just have to be patient. Gentle warming can be used but the solution should never be hotter than what can be comfortably held in the hand.

    Don't add any water as this negates the purpose of using a glycol or TEA. Once you add water the concentrate becomes susceptable to air oxidation. This is why HC-110 c0ntains no water and last so long. Water allows oxidation to occur.

    Jerry
    Last edited by Gerald C Koch; 12-04-2011 at 01:35 AM. 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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  6. #56

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    Quote Originally Posted by Gerald C Koch View Post
    When mixing up a concentrate with TEA or glycols be sure not to get the mixture too hot. Doing so causes some oxidation of the developing agents and results in a dark color. Actually everything will eventually dissolve at room temperature, you just have to be patient. Gentle warming can be used but the solution should never be hotter than what can be comfortably held in the hand.
    Jerry, thanks for the warning, and I wish I'd known that last night! I mixed some Instant Mytol, which is PC-TEA + glycol + sulfite with some proportions changed. My tests showed the pH was too high -- around 9.0 instead of 8.2. And a test-strip was dense as could be expected. I've been pondering since then what happened.

    I could have goofed my measurements, but I wonder if heating destroyed some of the ascorbic acid. I heated the TEA+PG mixture in a water-bath up to simmering, so the solution was at 90-95C for around 20 minutes. The Phenidone and ascorbic acid took that long to dissolve, even with constant stirring. Do you think such prolonged heat could destroy some ascorbic acid?

    What max temperature would you recommend? I notice that 50C is almost too hot to touch for me, so perhaps that would be a safe limit for these chemicals? I use 50C when dissolving Phenidone into water, but perhaps ascorbic acid is more fragile.

    Do you suppose that steam from the hot water-bath could have been absorbed into the solution? An Internet-search tells me that PG is hygroscopic, so having water-saturated air around it for half an hour might have been a poor idea.

    BTW, during that 20-minute stir, the solution gradually turned (and remains) a fairly strong yellow. Is PC-TEA or PC-Glycol normally yellow after mixing? Might this be due to the oxidation you warned about above?

    Thanks,

    Mark Overton

  7. #57

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    Hi Mark,

    Ethylene and propyl glycols are hydroscopic and will readily absorb water. I would mix everything in a glass bottle to avoid this problem. Keep the bottle lossely capped. Alkalis like TEa increase the rate of oxidation of ascorbic acid. What i did was to dissolve the ascorbic acid and phenidone in the glycol and once dissolved and cool add the TEA. Using glycol would also lower the pH. I used half of the total volume as glycol and half as TEA. If the pH is too low try 40 parts glycol to 60 parts TEA. You can add a small amount of TEA to the glycol to neutraiize the acidity of the ascorbic acid to help dissolve the AA. My final solution was yellow but not a strong yellow and did not darken as much as my first attempt using a lot of heat. So keeping things as cool as possible does seem to work. I used Dimezone instead of Phenidone as it is more stable in basic solutions.

    If your working developer is producing too much fog you can add some bromide. Potassium bromide will not dissolve in glycol or TEA but ammonium bromide will dissolve in TEA. This allows you to get some bromide restrainer into the concentrate. This will reduce any fog. Benzotriazole will also dissolve in the concentrate and also reduces fog. With either first find how much is needed for working strength developer to determine just how much to add to the concentrate. Years ago people would improve D-76 by adding 0.5 g/l of potassium bromide. This prevents one having to season the replenished developer. Hope all this helps.

    Jerry
    Last edited by Gerald C Koch; 12-04-2011 at 05:58 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.

    ~Antoine de Saint-Exupery

  8. #58
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    Jerry;

    Ammonium ion can cause fog in some emulsions. I would stick with Benzotriazole. Also, there is the chance that AA will dissolve more easily in TEA as you are mixing acid with base. I would be careful here though as it might not be "friendly". I have not tried this, so beware.

    PE

  9. #59

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    Hi Ron,

    I heated the TEA to drive off any ammonia. This was the only way short of using hydrogen bromide that I could think of for getting bromide into the concentrate. I didn't experience any fog with the amount of ammonium bromide that I was using. I originally mixed up the PC-TEA formula and did not experience any problems. But I added the AA slowly with stirring.

    It was fun to see what could be done to improve the PC-TEA formula. But, getting lazy in my old age I now use HC-110 for what little developing I now do.

    Jerry
    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

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    Very good idea. Wow, you drove off the Ammonia and effectively made the adduct! Now I think I can do that with Ammonium Sulfite. I have a pound of it. What do you think?

    If it works, that is the route to all kinds of HC-110 / PC TEA takeoffs.

    PE



 

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