Rodinal w/sodium ascorbategreenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I finally got around to making a batch of prints from HP5+ developed in Rodinal 1:100 w/4g/L sodium ascorbate added.
They look _very good_ with the expected "Rodinal look" but somewhat less graininess than Rodinal with or without sulfite. The difference isn't huge, but it's worthwhile.
-- John Hicks (email@example.com), January 23, 2002
I have a question: i can obtain easily Vitamine C (250g) but is has to be transformed to sodium ascorbate. How to proceed ?
-- Marc Leest (firstname.lastname@example.org), January 23, 2002.
I heartfully agree with Mr. Hicks. Rodinal (im my case: 1/50) and Sodium ascorbate make a great developer. Everybody who likes HP5 and Rodinal (a lot of people, I think), but who has sometimes problems with grain and E.I, should try this combination. But don't expect an revolution, it's more of an evolution. However, development time has to be modified. I process HP5plus (120) as follows: Jobo rotary Processor 270 ml Rodinal 1:50 with 1g Sodium ascorbate 20° C, 11 min (normal contrast). EI = 400
"Vitamin C" can mean free acid or sodium ascorbate, which is the sodium salt. Both come as powder and should act similiar, but may affect the pH of the solution in a different way, so the effect won't be the same. Also, the molecular weight won't be the same, so you would have to use less ascorbic acid in grams (I don't have the correct numbers). There is no easy "home-brew" way to convert the free acid into pure sodium ascorbate. But sodium ascorbate is cheap and easily available, so don't start experimenting. Regards Georg
-- Georg Kern (email@example.com), January 23, 2002.
According to Patrick Gainer: "Ascorbic acid [4 grams] is easily converted to sodium ascorbate by either 1 gram of baking soda or 4.5 ml of 10% sodium hydroxide. If you use the baking soda, add it to the ascorbic acid in a little water and let the fizzing subside before adding it to the working solution."
This information is in my article Appreciating Rodinal.
-- Ed Buffaloe (firstname.lastname@example.org), January 23, 2002.
Agree with all. I've been using this with FP4+ and find the difference isn't dramatic, but definitely worth the extra few minutes to make the addition. Nice to know the conversion to sodium ascorbate, as the local health/vitamin stores only seem to have the acid powder.
-- Conrad Hoffman (email@example.com), January 23, 2002.
i read a posting quite recently in which the writer had used ascorbic acid powder for this and the acidity apparently completely neutralized the alkali in dilute Rodinal. Buying sodium ascorbate should not be difficult. Maybe trying to neutralize ascorbic acid with an alkali as suggested above would have to be done quite accuately because of the very unbuffered nature of Rodinal
-- john stockdale (firstname.lastname@example.org), January 23, 2002.
In Denmark where I live, chemicals aren't readily available, but I find that my local pharmacy often is able to get me what I need.
-- Esben Rossel Torbensen (email@example.com), January 31, 2002.
If I ever said 4 parts of ascorbic acid to 1 part of sodium bicarbonate (by weight), I'm very sorry. The absolutely properly proper answer is the ratio of molecular weights, acid/bicarbonate, which is 176/84. It is easy in teaspoon measure. 2 tsp acid and 1 tsp baking soda (not powder)to the liter is close enough. If you try using the acid without neutralizing it, you will likely not get an image. No matter what you say about the potassium hydroxide in Rodinal, the amount of it in 1+50 Rodinal is not enough to neutralize the ascorbic acid. Pat Gainer
-- Patrick A. Gainer (firstname.lastname@example.org), February 06, 2002.
Question as regards Patrick Gainer's volumetric conversion into Sodium Ascrobate from 2 teaspoons Ascorbic Acid by the addition of 1 teaspoon of Sodium Bicarbonate - does this produce the 4 grams/liter of Sodium Ascorbate that is needed to be added to the Rodinal @ 1:50 for the reduced grain-effect?
-- john l bagtas (email@example.com), February 06, 2002.
Is the 4 grams per litre some kind of absolute found by testing? Or am I OK using 4 grams per 8x10 developing volume? I stick with 10ml of Rodinol syrup per 8x10 film unit whether developing one sheet of 8x10, 1 roll of 35mm or 8 sheets of 8x10. This is kept constant on the syrup whether diluted 1+25, 1+75 or whatever dilution I use. I do mix more than the minimum recommended amount each time so I generally have more than the 10ml per 8x10 film unit in the working developer. Any problems one can come up with for using the 4grams this way rather than with a per litre blanket recommendation?
-- Dan Smith (firstname.lastname@example.org), February 06, 2002.
I'm afraid I caused the confusion regarding how much bicarbonate to add to ascorbic acid to converit to sodium ascorbate. Patrick mentioned that you could add 4 grams/liter of sodium ascorbate to Rodinal (1:50), so when he gave the conversion I assumed he was referring to 4 grams of acid being converted. I have modified my recommendations in my article Appreciating Rodinal to reflect the information he has provided above. Patrick, if you have time I'd appreciate it if you would look the article over and make sure all the information is correct. I also show that you can convert using 10% sodium hydroxide, but I don't think I have the correct ratio.
-- Ed Buffaloe (email@example.com), February 07, 2002.
Answer to John Bagtas: It's close enough for government work. I only weigh those ingredients when I want to tell others what I'm doing and I want them to believe me. Kodak, in earlier days when they gave out formulas, recommended a scale that could measure in 1/10 gram units. Since we each establish what time and temperature are right for development, consistency of measurement is more important than absolute accuracy.
-- Patrick A. Gainer (firstname.lastname@example.org), February 07, 2002.
To Dan Smith: use 2 grams of sodium ascorbate with each 10 ml of syrup and you should be OK. 1 teaspoon is close enough. It dissolves quite quickly, so you can keep it dry and add it to the solution just before use. Pat Gainer
-- Patrick A. Gainer (email@example.com), February 07, 2002.
On the sodium ascorbate addition & development times and image contrast. I find, with my local tap water (very hard) that adding the sodium ascorbate to the developer gives more contrast in a direct comparison to straight Rodinol (1+75) as well a developing times about 1/3 quicker. If I go back to using distilled water for mixing the developer, will these findings still hold true?
I emphasize that the development is done with working negatives, shot back to back & processed within 20 minutes of each other (5x7's, 2 sheets of the same subject with no exposure changes, and 8x10's, 2 sheets of the same subject with no exposure changes). Not with contact printing step wedges, though I will probably do that in the future. In the 3 separate tests I have run, all using normal images from a days shooting, the sodium ascorbate, whether 2 grams per 750ml working solution (at 1+75 dilution) or 4 grams per 750ml working dilution pick up more contrast than the normal Rodinol at the same dilution without the ascorbate. Haven't worked enough with the 2 grams compared to the 4 grams to see any real difference. So far they both look good. Will check a bit more when I have time, but usually I end up testing on negs as I shoot rather than sitting in the darkroom being "Mr. Wizard".
In showing contact prints from the negs to others the contrast difference is noticeable. The shadow detail in both seems the same so in picking up contrast while cutting development time I don't seem to be losing anything.
Anyone else have info on the differences, dilutions & results?
-- Dan Smith (firstname.lastname@example.org), February 09, 2002.