WRT using Ascorbic acid in place of Sodium Ascorbate: The proprtions given by Ted Kaufman are right, but using Sodium bicarbonate to convert Ascorbic acid isn't a good idea IMHO. It'll result in the release of Carbon dioxide gas, which will partly dissolve in water to give Carbonic acid. This means some of the alkalinity of the developer will again be neutralised, and the dissolved CO2 may outgas on the film, causing pin marks or streaks.(posted 8090 days ago)A much more chemically elegant way to do the conversion is by using Sodium hydroxide. The byproduct in this case is simply water; the chemical reaction being:
C6H8O6 + NaOH -> C6NaH7O6 + H2O
The correct proportions to use are 2 parts of anhydrous Sodium hydroxide to 8.8 parts of Ascorbic acid; giving the equivalent of 9.9 parts (close enough to 10) of Sodium Ascorbate in solution.The use of a pH meter or an indicator paper to obtain a truly neutral solution is really the way to do it, but if you use proportions of 9 parts of Ascorbic acid to 2 parts of Sodium Hydroxide, you can be fairly sure that the solution will have just a slight excess acidity. Not enough to upset the pH of a developer beyond normal tolerances.
An excess of caustic soda would cause a greater change in alkalinity, and therefore processing time.