Water .............750 ml Metol‡............. 10 g Sodium Bisulfite....20 g Pyrogallol ........100 g EDTA-disodium†.......5 g Water to make.....1000 ml
‡ It is advisable to add a ‘pinch’ of Sodium Bisulfite to the water before adding the Metol, to aid preservation while mixing.
† Ethylenediaminetetraacetic acid disodium salt – a sequestering agent, not essential
Water............... 1400 ml Sodium Metaborate**.. 600 g Water to make....... 2000 ml
** I’m not sure what form the Sodium Metaborate (Kodalk) specified in this formula should be in. Mine is from Sigma Aldrich and has the formula BNaO2 4H20 – in other words it’s the tetrahydrate.
There was no way that the amount specified in the above formula would dissolve in 1400ml of water. I decided to mix only 1 litre total as I only had 500g of Metaborate, so tried 300g in 700ml. Even after hours on a heated magnetic stirrer it refused to dissolve totally.
I believe Kodalk was the octahydrate, so that might explain why I had trouble dissolving the same weight of tetrahydrate.
In the end I decided to go with it anyway, decanting off the clear solution above the insoluble residue. I plan on diluting it down to 2 litres and seeing if it will all dissolve in that. (will update when tested)
I mixed the usual proportions of working solution : 1+2+100 ratio of A+B+Water. It worked fine.
For a 500ml tank that’s 5ml Solution A plus 10ml Solution B plus 500 water. I always use distilled water.
Development time for the first film processed, Fuji Acros 100 120, rated at 100 ISO, was 13 minutes at 23.5°C, with 1 minute initial agitation and then one tank inversion every minute. A 3 minute pre-soak in distilled water with intermittent agitation was given prior to development.