Budding Chemist in the family

[Richard Man]

For my daughter who is majoring in chemistry, I gave her a bottle of expired developer for analysis in her independent project. She ended up testing the amount of sodium sulfite in the soup.

She is now working on the lab report and was frustrated that not much has been written in the scientific journals on the subjects since 1997, the time period from which her journal site starts their collection. I had to explain to her that B&W developers were invented a hundred years ago and any new research might be trade secrets in any case.

Then I pulled this out from the Film Developing Cookbook from Anchell and Troop. I think Schwalberg's quote should definitely be part of the lab report:


I also linked her to this:
http://silent1.home.netcom.com/Photography/Dilutions and Times.html

and told her that for Father's Day, either make me some Super Soup for shooting Tri-X at 6400 or two-bath C41

Any scholarly advices regarding sodium sulfite in developers?

All the Best

 

[Richard Man]

Yes, Anchell and Troop's book pretty much said that. Her particularly lab investigation shows that a large amount of the sodium sulfite has disappeared, so one question she wishes to address is the oxidation rate of it in the developer.

Thanks!

 

[Alan Johnson]

If you leave the part full bottle a long time sealed up and all the oxygen contained in it reacts with the sulfite, when the bottle is only 10% full the ratio of the volume of air (20% oxygen) to the volume of developer is over 80 times that when the bottle is 90% full so the sulfite is consumed ever more rapidly as the level falls.So this is not really the way one would design an experiment to measure the reaction rate of sulfite and oxygen because it introduces complicating variables.