Would you measure Vitamin C with teaspoons to get long-lasting dev?
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?
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!
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.
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 Gerald C Koch; 03-28-2013 at 12:11 AM. Click to view previous post history.
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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.
Originally Posted by Gerald C Koch
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.
Originally Posted by Bruce Osgood
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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.
Originally Posted by albada
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.
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.
Originally Posted by jcoldslabs
Oh, the Vitamin C goes in when the concentrate, so no need to add any later
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.