ascorbic acid as a substitute for metol and hydroquinone

[RalphLambrecht]

how woul oneuse ascorbic acid as a substitute for metol and hydroquinone?

[analog what is that?]

General info says that ut can replace one, but ot the other, in respect to its chemistry.....
Metol forms a superadditive pair with Hydroquinone
Phenidone forms a superadditive pair with Hydroquinone
Phenidone forms a superadditive pair with Ascorbic acid

[analog what is that?]

And phenidone with sodium ascorbate is a powerful pair......

What you should be looking for is a substitute for phenidone available in the mall, other than coffe.
I suggest looking at common thea.

[Rudeofus]

Ralph,

the unblinking eye website has a few articles about superadditivity and ascorbate developers: this one describes how developers work in general and which compounds are used. This one describes superadditivity, and here the merits of ascorbate are discussed. Also look for relevant postings here on APUG for extra info, e.g. in this thread.

[Michael R 1974]

Based on everything I've read, there is so much more to developers than reduction activity. So although it may be mathematically possible to substitute one developing agent for another (eg replacing Metol with Phenidone or derivatives is a popular one), that does not mean the developer will perform the same way regarding all the different image characteristics involved (acutance, graininess etc). Once you change the developing agent I suspect the entire formula needs to be revisited.

I'm not a chemist, but it seems to me the highest quality, most balanced developer formulas are rarely simple substitution formulas regarding the developing agent(s). The are carefully balanced, complete formulas.

[analog what is that?]

That is true Michael, I'm a chemist and can testify that they (we) didn't learn squat about this in school, neither on fixers and what takes place, just two simple formulas on each respectively, and 5 minutes talk of general principles in all those years!
Reading a few threads here on the subject and subtracting some of the tallest claims you can learn more about the subject in a couple days....

[Gerald C Koch]

The similarity between hydroquinone and ascorbic acid is only superficial. Their actions in developers is quit different. Any MQ or PQ developer must be modified when substituting ascorbic acid or sodium ascorbate.

[nworth]

I'm not sure about superadditivity between metol and ascorbic acid, but the combination deserves some attention. I experimented with them in a couple of print developers, and I found the results quite rewarding. Normally, ascorbic acid and PC combinations produce rather harsh print developers, with inferior tone. But metol seems to moderate things while still maintaining the necessary contrast. I have made at least one quite good MC cold tone print developer.

[RalphLambrecht]

That is true Michael, I'm a chemist and can testify that they (we) didn't learn squat about this in school, neither on fixers and what takes place, just two simple formulas on each respectively, and 5 minutes talk of general principles in all those years!
Reading a few threads here on the subject and subtracting some of the tallest claims you can learn more about the subject in a couple days....

let'd try it:
are you willing to To shareshare the fo the formularmula?

[analog what is that?]

Naaaa, you have to wade through all the threads like everyone else, it is about sharing you know, not like in a workplace, ordering those below on the corporate ladder around!