First, I have not had any problem getting the potassium bormide and sodium metabisulfite to go into solution in glycol, though it does involve heating the glycol to around 250º F. But at this temperature both go intoi solution quite easily.Originally Posted by Tom Hoskinson
Tom is basically right in that the omission of potassium bromide and sodium metabisulfite does not make a lot of difference and may not be immediately apparent in your negatives. However, if you specifically test for it by running BTZS types testing in which test films are developed for different periods of time, and the results then read with a densitometer and plotted, you will indeed find some differences. The difference will probably not be evident with shorter development times but with the longer development times one would see with N+ development or with development for alternative printing the difference is quite obvious. In these cases the lack of potassium bromide results in slightly higher B+F levels and the lack of metabisulfite results in slightly more stain. This may not be important if you are using the 1:1:100 dilution and developing only for regular silver gelatin printing, but it definitely matters with the long development times we often need for alternative printing, where any differnce at all in the stain becomes very important because of the highly actinic nature of brown stain.
I am currently working on some refinements of the Pyrocat-HD formula involving non-symmetrical mixtures of Solution A and B to make it more active for alternative printing and my current thinking is that the best place for the potassium bromide is in the Stock B solution rather than in the Stock A. So the next time I mix a new batch of Pyrocat-HD I plan to try to mix the bromide in with the Stock B, assuming it be soluble with the carbonate solution?
As for the sodium metabisulfite I plan to continue to put it in the Stock A solution. Although it is not needed as a preservative in this solution, it nevertheless continue to have some impact on negative stain because it releases as sulfite when mixed with water and the sulfite, in even minute quantities, has an impact on total stain, especially evident with long development times.