I'm about to mix some PC-TEA for the first time. The shop from which I bought the chemicals had TEA and ascorbic acid with the highest purity (> 99%), but Phenidone with 97%.
Should I use the amount given in the formula, or use a little more (such as X/0.97)? I guess it's nothing to be worried about...
My second concern is about how much Phenidone to use. The 3rd edition of the Darkroom Cookbok specifies 0.5g per 100ml Stock, most sources state 0.25g for the same volume. Does the larger amount just provide some safety for higher dilutions or does it significantly change the results in normal use (i.e. one-shot use, dilution 1+50 and two rolls of 135/36 per 500ml).