Sugar in developers and toners?

[MikeK]

Found a reference to D-19 a high contrast developer, in one of my old darkroom magazines from the mid 1980's. The discussion was on rotary processing, but finished with the author recommending this developer mixed with an unpecified amount of sugar. So for you clever chemists, what does the addition of sugar do to a high energy developer/ and what amounts do you you think would be added.

I also have a formula from a old english text book that uses hypo and sugar for brown toning post cards. Any ideas on why sugar in that formula?

Mike

 

[Nick Zentena]

Brown sugar brown toning? Maybe they used a hot plate afterwards to glaze the print. The sugar would glaze things.

I'm always learing of old wierd formulas.

 

[Jordan]

Sugars can act as reducing agents under certain circumstances. For example, there is an old-school qualitative test for aldehydes that involves the reduction of silver nitrate to metallic silver which deposits as a "mirror" on the wall of the test tube. (This is called the "Silver Mirror Test" but I think it's formally known as the Tollen's test.) Most sugars are hemiacetals and act as aldehyde equivalents in this reaction.

In more common use there is ascorbic acid, which is definitely derived from the carbohydrates, and is most certainly a developing agent. But it isn't a hemiacetal.

My guess is that the recommendation to add sugar has something to do with preventing damage to the film or reducing precipitation in the developer. But I'm not sure how it would work in that regard.

 

[reellis67]

I have seen recipies for two bath developers that use sugar to retard development in the first bath. If I remember correctly, Kodak SD-4 and SD-5...

- Randy

 

[Ryuji]

Sugar is probably used to reduce gelatin swelling or to prolong the life of the developer, but I am not very sure of the intention.

Reductones are useful developers, but sugars like glucose and sucrose aren't really developing. In order to make developing reductones, these sugars have to be cooked in a very strong alkaline solution. But the temperature and timing of heating is rather critical and I wouldn't try to do that myself...