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.
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.
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
use the two chelating agents mentioned and use only de-ionized water.
Originally Posted by Gerald C Koch
Alan and Jerry quickly perceived my evil plans. :cool:
Originally Posted by Alan Johnson
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...
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.
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.
Originally Posted by Michael R 1974
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.
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.
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.
Originally Posted by Gerald C Koch
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.