TECHNICAL COMMENT
(Up-date and Corrections)From Brian Savage (Technical Advisor)
SODIUM CARBONATE TO SODIUM BICARBONATE (CRCN No.75, Page 3):-
This raised the point that Sod. carbonate, in time, will slowly change to Sod. Bicarbonate on prolonged exposure to air by obsorbtion of CO2 and water vapour. Baking to turn it back is correct. The change occurs at quite low temperatures.
Boiling water will break up bicarbonate into carbonate and carbon dioxide. This is the basis of the use of bicarb. raising agent in baking - "baking- soda" - the carbon dioxide gas makes the cake dough rise.
CORRECTION: Part of the sentance was omitted from my "General Comments".which made it read wrong. Here is the complete paragraph with the omitted words underlined:-
The Classic E6 process calls for seven baths (including Stabilizer).
The reason for this is that it cuts down the contamination of each bath as the film is transferred from one bath to the other and the whole thing is designed to produce maximum working life for all the solutions. Kits using less baths are all something of a compromise,sacrificing longevity of the solutions for convenience and in my view, are designed to process only the designated number of films all at one go, or one after the other on the same day.
(With aplogies, Editor).