PC-TEA Replenisher

Discussion in 'B&W: Film, Paper, Chemistry' started by Reinhold, Jan 1, 2005.

  1. Reinhold

    Reinhold Subscriber

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    Yesterday, I developed 27 sheets of 8 x 20 inch HP5+ in PC-TEA, using the replenisher suggested by Pat Gainer in this post... http://www.apug.org/forums/showthread.php?t=10684

    It worked great. Here are the details:

    The developer was Sandy King’s variant of PC-TEA, which added an additional 0.2g of KBr to keep fog to a minimum. I developed by inspection in homemade trays, designed to hold 3 liters of chemistry. I found that I needed a dilution of 25 ml of PC-TEA per liter of water (1+40) to keep the developing times down to about 9 minutes. I replenished after each film, and was able to process up to 10 sheets in 3 liters (with 10 ml of replenisher added after each film).

    Pat suggested a replenisher consisting of only Ascorbic acid and TEA to keep the ascorbate level up, and maintain the Ph. My first batch was 100 ml of TEA, (heated to 100C,) and 9.0 g of ascorbic acid. It worked nicely, but the viscosity made measuring out 10 ml and blending it into the tray of developer each time a “fussy” and time consuming task. I needed a faster way...

    For my next batch, I dissolved the 9 g of AA into 100 ml of water, then added 100 ml of TEA (at room temperature, no heating needed), which gave me an easily measured, easily blended 50% diluted replenisher. Naturally, I now added 20 ml of the diluted replenisher after each film. Since there’s no Phenidone in the mix, there’s need to worry about longevity, either.

    Developer activity, contrast, and tonality was consistent over the 10 film/replenishment period. I was processing a wide variety of subjects under a wide variety of lighting conditions, and developing times varied quite a bit according to subject and lighting. Wherever I had subjects of similar contrast and lighting, the developing times held constant, despite being replenished. Where contrast and lighting varied severely, developing by inspection saved the day. Except for the time I forgot to stop down, I got 26 beautiful “keepers”.

    As Ole has noted in another post, inspecting the emulsion may be the better way, depending on how a developer works. With PC-TEA, I inspected the emulsion, and looked for shadow detail, rather than inspected the base side and looked for highlight detail. ‘Been doing it that way for nigh onto 40 years.

    This was not a series of sensitometric experiments, I’ll leave that up to the “technicians” among us, but this project came to a great conclusion, with the help of a great guy I’d like to meet someday...

    Let’s hear it for Pat Gainer.

    Hip, Hip, Hooray......
     
  2. gainer

    gainer Subscriber

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    The phenidone is not the problem in cases of premature death. An acidic solution of ascorbic acid or sodium ascorbate without phenidone in water will take up oxygen and form dehydroascorbic acid, which is not a developing agent. I suggest you use propylene glycol to thin out your C-TEA. When you add the water, you activate the TEA's alkaline property. It probably forms an organic equivalent of sodium ascorbate. It must do something of the sort because there is no inorganic base in the solution.

    I like to meet people, but you are about as far as one can get from West Virginia and still be in the U.S. and I am too old to travel that far.
     
  3. sanking

    sanking Member

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    The viscosity of developers mixed in TEA must be considered in mixing the working solution. At room temperature of 70º F the stock solution is so viscous that it makes accurate measurement almost impossible so heating it before measuring is highly recommended. I heat the developer for 15-20 seconds, with the cap off, in a microwave. Then I extract the required amount with a syringe, and squirt it into the water. But in order to get in all of the solution in the syringe into the working solution you will need to flush it out several times with the working solution.

    The extra time that must be spent in heating up the TEA and in dispensing the stock solution to make a working solution negates to some extent the convenience of the single solution developer. In practice some may find Pat's two part ascorbic acid/phenidone formula, in which the first part is mixed in propylene glycol (which is much less viscous) and the accelerator added when you mix the working solution, to be as convenient as the one solution developer.

    Sandy
     
  4. Maine-iac

    Maine-iac Member

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    I concur wholeheartedly. I can mix up a liter of developer in less than three minutes this way.

    Larry
     
  5. Reinhold

    Reinhold Subscriber

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    Pat...

    Thanks for the “heads up” on ascorbic acid oxidizing in an aqueous solution, that caught me by surprise. Since I needed a replenisher for this particular project, speed of preparation was my first concern, longevity was incidental. Being able to mix it at room temperature was a big help in this instance. For the future, I’ll follow your advice to reduce the viscosity with something other than water.

    Which brings me to the following post on Puresilver... http://www.freelists.org/archives/pure-silver/12-2004/msg00347.html
    There, a post on 17 Dec. suggests diluting TEA with methanol. Hmmmm...

    Mixing a stock replenisher of 9.0 g of AA in 100 ml of TEA, and diluting it with methanol just before using sounds like a practical solution...

    I’m not fixated on replenishing as a general practice, it’s just that there are times when the scope of the project makes replenishing more expedient in my particular darkroom.

    Thanks for watching over me, us younger sprats need an occasional reality check..
     
  6. gainer

    gainer Subscriber

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    That alcohol dilution should last quite a while if the alcohol is pure. I think the best is to be obtained at auto parts stores as gasoline antifreeze or dryer. It comes as methanol or isopropanol, both as dry as possible. One of the problems with alcohols is their affinity for water. Absolute alcohol does not remain as such for long if there is any moisture in the air. Of course, if you mix only enough of your replenisher for one sesion, it won't make much difference what you dissolve it in. You're probably not thinking of storing it for months.