elmarman
Bail out the Brits too !
years ago I used 'Calgon' which was Sodium Hexametaphosphate when mixing developer formulae - then Geoffrey Crawley told me before he died that the 'Calgon' as sold in British Supermarkets is NOT the same any more and should NOT be used in developers. So now I use boiled tap water, filtered. In some llford Formulae I see they use 'Sodium Tripolyphosphate' -- the questions are : Is is a water softener like original Calgon OR does it have some other effect such as on the Ph ? can I leave it out and just use boiled water as before ?
Freakscene
Obscure member
Yes. https://en.m.wikipedia.org/wiki/Sodium_triphosphate. No effect on pH.
Whether you need it or not depends on the divalent cation concentration of your water and the concentration of them as a contaminant of your photo grade chemicals (it is to counter this latter source that sequestering agents are usually added to developer formulae).
Marty
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elmarman
Bail out the Brits too !
Thanks for you quick and full reply !
Peter
Peter
elmarman
Bail out the Brits too !
PS :I made up some 'Microphen' Formula using boiled water and it gave some good negs but with some precipitate ion the bottle no doubt because of interaction of the Sodium Sulphite with the Calcium and Magnesium salts in the water still.
Fotohuis
Well-known
Better using demineralized water e.g. Brita (TM) water. Or use the photo-Calgon. Anyhow small precipitates you can filter out by a coffee filter.
Chemlover
Newbie
If the water is pure enough, it's not necessary for to add it. But worth to mention is that Sodium tripolyphosphate also has the character of being oil-resistant when coating paper.