Preparing concentrated stock solution of Diafine

[Steffen Alexander]

Im about to prepare new solutions of Diafine. Can the powder be dissolved in less water than 1 gallon to get a stock solution? I just have 2 2l bottles for stock solution and 2 1l bottles for working solutions at hand. To fit the volume of the bottles I have to prepare an stock solution of 2,7l instead of 3,8l.

 

[Mike Wilde]

Usually the limiting factor for storing concentrated stock solutions is the solubility limit of any sodium sulfite in the developer dry mix.

I had a can of dry chemistry of D-19, quanity to make 5 gallons working solution. Was meant originally for aerial military photography.

The lower limit for the d-19 stock solution I discovered was about 5l. Actually I added a bit of metol, and a buch of sodium carbonate and turned it into a very warm toned dektol like print developer. Bromide higher than normal; was used with long outdated Ansco Indiatone warn toned portrait paper to warm, and also suppress the fog a bit in the image.

What I did was mix under the limit with about 3L of hot reverse osmosis filtered water, let cool and then descant off the supernatant, which I presumed had many of the developer components fully disolved. The sludge of presumably mostly sulfite got mixed in with more hot water until it would all stay in solution. By taking the two bottle route I hoped to minimixe oxidation of the bulk of the developing agents in bottle A as I worked the solubility limit of bottle B with repeated heat, add an new increment of hot R./O water, stir, and let cool over a number of days.

 

[albada]

My reverse engineering of Diafine shows that solution A has just under 40 g/L of sulfite, and solution B just under 60 g/L. This means that you should be able to mix A at double concentration, and B at 1.5x concentration, and keep both under 100 g/L of sulfite.

But instead, I suggest getting a couple of clear plastic soda- or water-bottles that hold 1L or 1.5L. They are made of PET (aka PETE), which blocks oxygen well. They can store the solutions for a while until you get around to buying more bottles.

Mark Overton