Quote Originally Posted by Photo Engineer View Post
Patrick;

Sulfite also drags the oxidation of HQ to the right by scavenging the quinone by generating HQ monosulfonate which itself is a weak developer.

But, as a number of people have said, the use of more than two developing agents is a real reach. I know that Haist has said that, and probably Henn and Lee as well.

BTW, I have also made mention elsewhere of ETA developers. They are distinguished from superadditive developer combinations by having the pH adjusted to be optimum for the primary developer. The primary developer is present at very low concentrations. The other developer is not really active under these conditions except to regenerate the primary developer. These are unique and AFAIK there are not currently on the market.

PE
I am a chemist by training, though not an expert in photographic chemistry. However, I was reading about properties of developers one day and it occurred to me that an ascorbate/para aminophenol developer adjusted to pH 9 or so should activate the para aminophenol (perhaps weakly) but not the ascorbate, and that the ascorbate should regenerate the para aminophenol under these conditions. Does this sound something like what you are describing?

One more thing. I understand that when ascorbate is oxidized it increases the acidity of the solution. If so would a developer such as I outlined above have a compensating effect by lowering the local pH in the gel in the areas of most active development, thereby inhibiting development in those areas?

Alan