Quote Originally Posted by Murray Kelly View Post
Finally I have a real question. Given what you have said, what would the difference in the pH be of (say) your P-C-Borax developer above using an unlikely but possible scenario that one had a box of pentahydrate versus a box of pure decahydrate and made the developer from one or the other?
Approximately 20g /litre would show a difference of how much pH?
My suspicion is that the single decimal place pH meter wouldn't help one distinguish the one from the other. Yes/no?
It takes a fair amount of change in amount of borax to make a change in pH of a solution of borax. However, the concentration of borax has a greater effect on local dynamic changes in pH than will be seen after equilibrium is reached. Frankly, I am not one to quibble, as PE will testify. However, the difference in number of molecules between 2 grams each of penta- and decahydrate is about 30%, so if you had all penta and thought it was decahydrate, you would be getting the equivalent of 2.62 grams of the specified decahydrate. Would that make a visible difference in the output of D-76? It depends on how sensitive you are to such things. I take it that the purification process would be worth while if one could not buy the Photo grade stuff, of PE and Kirk Keyes would not chastise me for trying to put Photo Formulary out of business by doing it.