Would you measure Vitamin C with teaspoons to get long-lasting dev?

Discussion in 'B&W: Film, Paper, Chemistry' started by albada, Mar 27, 2013.

  1. albada

    albada Member

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    I'm thinking of designing a developer that requires you to add Vitamin C (ascorbic acid) separately using a measuring spoon.
    Would this be too much extra hassle?

    You would do the following:
    1. Pour developer into your beaker as usual.
    2. Measure out 1/2 or 1 teaspoon of Vitamin C.
    3. Stir until dissolved (a couple of minutes).

    I discovered that ascorbic acid can be measured consistently (within 5%) using a measuring spoon by first scooping out a heaped spoonful, then compacting it by pressing firmly upward against a flat surface, and then scraping it level. That gives you an accurate packed-and-leveled spoonful.

    Adding ascorbic acid separately means you can mix your own ascorbate-based developer and have it last many months instead of just a few weeks. For example, you could mix your own XTOL-clone, and then you would not need to mix 5 litres of XTOL and waste much of it when you can't use it all. But you'd need to do the teaspoon-routine each time you develop. Is it worth the extra effort?

    Mark Overton
     
  2. jcoldslabs

    jcoldslabs Member

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    That would be totally worth it to me. Presently, I mix HC-110 from concentrate for each developing session, so I'm used to the mixing aspect. If I could get Xtol-like results with a long shelf life simply by adding some vitamin C each time, no problem!

    Jonathan
     
  3. Bruce Osgood

    Bruce Osgood Membership Council Council

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    If you are talking about adding the Vitamin C to a previously mixed and stored, ready-to-go stock solution when preparing to develop film, then yes, as a single, last minute addition with a teaspoon would not be a hassle.

    But if you are talking about making a stock solution that uses a teaspoon amount of Vitamin C in the formulation stage, I think I would find it easier to use weight rather than volume since I've set up to weigh all other ingredients.
     
  4. Gerald C Koch

    Gerald C Koch Member

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    Measuring by volume rather than weight is inaccurate as it depends on crystal size. It doesn't take that much more time to weight out the correct amount. For small amounts a square of paper works well to protect the pan on the scale. For larger amounts paper baking cups work well. Remember the tare weight of whatever you use.
     
    Last edited by a moderator: Mar 28, 2013
  5. albada

    albada Member

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    Interestingly, it's possible to formulate a developer so that sloppy measurement of ascorbic acid makes little difference. An example is PC-Sulfite in this posting. For example, if AA is low, then having less secondary dev drops activity, but the rise in pH boosts activity, cancelling each other out, yielding about the same activity.

    Regarding weighing, here's my sermon:
    As Jerry said, measuring by weight is more accurate. Electronic scales with .1 or .01 g resolution cost only US$12-15 on amazon. That's the cost of just 3 rolls of film. So there's no excuse to not have one (or two). Search for "scale .1g" or "scale .01g".

    Yes, a last-minute addition for single-shot use is what I had in mind. Sorry that I didn't make that clear.

    Mark Overton
     
  6. Keith Tapscott.

    Keith Tapscott. Member

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    I don't know if it's worth the extra effort. You could try a simple fine-grain formula like DK-76b and add some vit-c to the working strength solution to see if it works well, otherwise stick with Xtol.

    http://www.digitaltruth.com/data/dk76b.php
     
  7. Worker 11811

    Worker 11811 Member

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    Just a shot in the dark.

    What about making a saturated solution of ascorbic acid in distilled water then measuring a certain amount of the liquid? (tablespoons full, etc.)
    It's a lot easier to measure liquids accurately and, assuming room temperature ≈20ºC, you should always get the same amount of solute.
     
  8. P C Headland

    P C Headland Subscriber

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    If you want something like that, you might want to make up some PC-TEA. Simple to make, lasts at least 5 years, and (for me at least) seems to have a combination of the best bits of Rodinal and Xtol. Like Rodinal, it can turn from a pale straw colour to dark tea, and still works the same. Like Xtol, it gets good film speed and shadow detail, with little grain.

    Oh, the Vitamin C goes in when the concentrate, so no need to add any later :wink:
     
  9. Alan Johnson

    Alan Johnson Subscriber

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    What evidence is there that the phenidone and sulfite part of the developer would be long lasting?The question is based on an unproven assumption.
     
  10. timhenrion

    timhenrion Member

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    FX-55 ?
     
  11. Alan Johnson

    Alan Johnson Subscriber

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    In FX-55 the phenidone is added with the ascorbate.
    If it was wished to use spoon measures the powders would probably have to be mixed together first.
     
  12. jp498

    jp498 Member

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    I'd be happy with shoveling in ascorbic acid, liquid concentrate (I have cheap pipettes for that), or how about "sugar packs" or tablets of the stuff.
     
  13. Gerald C Koch

    Gerald C Koch Member

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    The use of ascorbic acid in the food industry is wide spread. Why, because it readily scavenges oxtgen and therefore protects other chemicals. Because of this it is unstable in solution so making up a concentrate solution is really of no help. As has been stated over and over again on APUG the main problem is Fenton oxidation which is catalysed by iron and copper in the chemicals themselves and in the water used to make up solutions. Use only de-ionized water for making up solutions. Do not use distilled water as this is often made using copper equipment. The stabilitry of ascorbates is improved with the use of certain chelating agents such as salicylic acid and TEA.

    My suggestions would be either to mix up the developer without the ascorbate and then weigh it just before use

    OR

    use the two chelating agents mentioned and use only de-ionized water.
     
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  15. albada

    albada Member

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    Alan and Jerry quickly perceived my evil plans. :cool:

    In ascorbate developers, the ascorbate typically is destroyed first (by Mr. Fenton), so my idea is to add it separately. But as Alan points out, the sulfite and Phenidone might not last long either. PE has said that Dimezone S is more resistant to hydrolysis than Phenidone, and we know it lasts for over 6 months in capped bottles of XTOL. Sulfite is oxidized by air, changing it to useless sulfate, but my calculation of air-moles versus liquid-moles says this won't be a problem in typical usage. So maybe, just maybe sulfite+Dimezone will last long. Only testing will prove that, and I wanted to know if this add-C-separately idea appealed to people before doing that testing. Hence my posting.

    jp498 suggested tablets. That's a good idea: Vitamin C pills are widely available in 250, 500 and 1000 mg sizes. That would solve the measurement problem. Hmmm...

    Mark Overton
     
  16. michael_r

    michael_r Subscriber

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    I'm confused about the Phenidone/Sulfite part. Would this be mixed in a solvent like TEA that does not readily transfer Oxygen? Otherwise wouldn't a Phenidone-Sulfite-Water solution be pretty short-lived/unstable? I'm thinking of POTA for example.
     
  17. albada

    albada Member

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    Yes, this would be water-based ready-to-use developer like D-76 or XTOL, except that some Vitamin C would be added just before use. And Phenidone is subject to hydrolysis, so I'm hoping that Dimezone S will last longer.

    Mark
     
  18. Alan Johnson

    Alan Johnson Subscriber

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    Here I can buy a 120w 6-speed hand held mixer for GBP 8.
    The ascorbic acid and phenidone could be mixed together then measured out with a spoon?
    On second thoughts that's a bit industrial and not safe for amateur work.
     
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  19. Zathras

    Zathras Subscriber

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    Since I prefer Metol to Phenidone, I've been playing with the idea of using D23 as a sort of stock solution since the required amount of Metol is only .2 grams per liter of Gainer's formula. I plan to make the working solution by starting with 900ml of water, adding 2.0 grams of ascorbic acid, 26.6ml of D23 and 6.0 grams of sodium metaborate, in the form of PMK "B" solution and topping it up to 1.0 liter. I figure that the 100 grams of sodium sulfite in the D23 should preserve the Metol for at least 2 months if stored properly.

    I'm basing my idea on Pat Gainer's Vitamin C developers, but trying to eliminate errors in weighing out small quantities of Metol every time. Since I do use D23, I thought that it might make a good stock solution for the Metol, and if I don't like the results from Gainer's developer, I still have D23.

    When diluted, there will be less than 3.0 grams of sulfite in the developer compared with none according to Pat's formula. I don't know if that would make a big difference or not, so I'll need to test carefully. When I have the chance, I'll run some BTZS tests with a couple of films and see what happens.

    Since I'm not trying to make a developer that works like Xtol this may not be what the OP has in mind. I was just considering an alternative.
     
  20. michael_r

    michael_r Subscriber

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    Gerald, what is the difference between distilled, deionized, or distilled and deionized, or "equivalent to distilled" - presumably by reverse osmosis? I have always used distilled water, but now I'm wondering if perhaps rather than improving things vs tap water, my distilled water is the reason my XTOL always seems somewhat "weak" even when freshly mixed. Is that possible, of would Fenton oxidation only take place over time with storage. I'm confused about water.
     
  21. Gerald C Koch

    Gerald C Koch Member

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    There are 3 ways to eliminate impurities in water

    1, Distillation, the oldest method. Water is vaporized, leaving the impurities behind, then allowed to cool using a condenser to form liquid water again. Traditionally a copper condensor was used for its large heat transfer capabilrty. If a metal condensor or catch container is made of metal then the water may become contaminated with metal ions. A particular problem is with copper. Even ordinary glas is a problem in preparing water for conductivity experimnts. The sodium in ordinary glass leachs out. Only fused silica equipment can be used.

    2 De-ionization, the water is passed throught a mixed resin ion exchange column. Metal ions are replaced with hydrogen ions and anions with hydroxide ions. The hydrogen and hydroxide ions combin to form water.

    3 Reverse osmosis, water under great pressure is forced through a semipermeable barrier. Large ions cannot pass through leaving, in theory, pure water.

    Iron and copper are common contaminants of the chemicals used for making developers. The wrorst offenders are probably sodium sulfite and sodium carbonate. So just using purified water may not help. A chelating agent is the best way to insure the storage life of ascorbate developers. Salicylic acid chelates iron and TEA does the same for copper.

    With the right amount of iron III all the ascorbate in a solution can be destroyed in an hour or so. It can be that fast.
     
    Last edited by a moderator: Mar 29, 2013
  22. albada

    albada Member

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    And that's why I started this thread: My idea was to add the ascorbate at the last minute.

    Here's a related idea: Add the Vitamin C as pills!
    You can buy 1000 mg Vitamin C pills that are actually powder in gelatin capsules. Here are examples:

    It's easy to pull gelatin capsules apart, and pour out the powder into your beaker. So the procedure for developing would be:

    1. Pour developer into beaker.
    2. Add contents of a couple 1000 mg Vitamin C pills, and stir until dissolved.
    3. Develop as usual.

    This avoids the inaccuracy of using teaspoons, and eliminates the need for a scale. Is this appealing?

    Mark Overton
     
  23. Doremus Scudder

    Doremus Scudder Member

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    Hello Mark,

    I have used both vitamin C tablets and capsules as developer additives (I add ascorbic acid to PMK for expansions). Unfortunately, it's not so simple as "add contents ... stir until dissolved." All the vitamin C products I've tried also have binders and anti-caking ingredients (usually corn starch, etc.) which needs to be filtered out. I usually dissolve the powder from the capsule/tablet in a separate small amount of water and then filter that before adding it to the developer. Unless you can source some ascorbic acid in capsules that is in pure form, it may be more trouble than just weighing out the right amount of powder.

    Best,

    Doremus


    www.DoremusScudder.com
     
  24. michael_r

    michael_r Subscriber

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    Interesting. So a couple of follow-ups since there are two types of purified water readily available to me (again, the only supposed problem I've ever encountered with purified water is with XTOL):

    Type 1- Label says: steam distilled (and ozonized), mineral salts 0PPM, Fluoride ions 0PPM

    Type 2 (the brand I've always used)- Label indicates: Treated by deionization and microfiltration (and ozonized), equivalent to distilled, mineral salts 5PPM, Fluoride ions 0PPM

    That's all the labels say so are either of these likely to weaken my XTOL upon mixing? I suppose it is impossible to answer without a detailed knowledge of the machinery used, but what are regular dummies like me supposed to do when Haist etc say used distilled water for ideal mixing? If the distilled water is no good, I guess I'm just S.O.L. since I can't very well start searching the globe for distilled water that has no Iron in it.

    Also, with respect to chelating, sequestering etc, I guess I would have thought Kodak included all the pertinent additives in packaged XTOL (which is what I use). I had always assumed since most packaged chemicals (even those containing ascorbate) are supposed to be suitable for use with tap water of varying quality, use of distilled water would make the stock solution even more stable if anything.

    Or perhaps I'm just worrying about nothing.


     
  25. albada

    albada Member

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    Your posting made me take a closer look at the links I provided yesterday. Of the two makers of capsules, one includes 20 mg of ascorbyl palmitate, which Wikipedia says is only slightly water-soluble. The other is "Pure Ascorbic Acid" by Thorne Research, and its ingredients-list says it's indeed pure. But having only one brand of suitable capsules available is risky. A google search for "pure ascorbic acid" turns up several vendors of powders, so it's prudent to stay with powder as you suggested.

    Mark Overton
     
  26. Clay2

    Clay2 Member

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    In pharmacy that used to be called stricken or struck measure. A heaping measure was struck level with a card.

    Remarkably repeatable.

    Best regards,

    /Clay