There is really no way to compensate for the lower pH of Borax. The threshold pH of pyrocatechin is about 10.5 so the low pH of Borax just doe not work.

You might, as Pat Gainer has suggested, mix the borax with some sodium hydroxide as this will increase the pH. I don't know exactly how of each is needed but if I were doing this I would just first mix up a borax solution, then add sodium hydroxide until it reached a pH of about 11 - 11.5.

The working pH of Pyrocat is about 10.9 - 11.2.

Sandy King


Quote Originally Posted by phritz phantom View Post
i was looking at the formula for diXactol at the same time, so i got the sod. hydroxide and pot.carbonate confused.g
but good that you mention the error with the metaborate, because after you mentioned it i dug out the bottle of sodium metaborate which came as the b-solution in a pyrocat-hd package i ordered from lotus in austria years ago.
the instructions said, it should be mixed 1:2:100 (dev:b-sol:water)

say, if i wanted to use borax (or something else of lower ph) as the b-solution. because it's said that borax gives finer grain. since the ph is lower now, how would i compensate for that? with a longer developing time or with a higher percentage of b-solution in the working solution (like: 1:2:100 or even 1:3:100).
and would the less active developer effect the light sensitivity of the film too? in other words, would i need a lower asa rating?

on a related note:
one thing that always interested me, was, w.eugene smith said in the "darkroom" book, that he uses d-76 with three times (more or less, i can't remember exactly) the normal amount of borax, because this gives him a negative with more shadow detail. is this because of the higher ph-value? and would that effect be even more when one would use carbonate or hydroxide?