Over the past few days I have been formulating a couple of different developers with the hope of acheiving a better tone gradation from my Efke film. [PL100].
I test using BTZS methods and shoot that way as well and found that D76 1+1 gave a very good result but the grain was a bit smooth for my liking. When I say that I mean it felt not quite as sharp as it could be.
I am not a photographic chemist but a little bit of research indicated the pH of D76 is about 8.5 so I used that pH as a lowest level pH to work from. According to my pH meter the store bought D76 was 8.5.
I looked at the 2/5 ratio of Metol/Hydroquinone and decided on a slightly higher Metol to Hydroquinone but with the hope of retaining the D76 superadditive affect.
I have always liked the tonal gradation with formulas based on Sodium Carbonate but they are usually not fine grained.
I found a couple of old Agfa developer formula that used Potassium Carbonate instaead of the Sodium Carbonate and i did find [subjectively] they had a slightly different look to the SC version. I retained Borax because it is supposed to be a bit softer working on the grain and gave it a "touch up" with the Potassium Carbonate.
D76 normally has about 2 grams of Borax to the litre but also has 100 gms of Sodium Sulphite. I increased the Borax and added the Potassium Carbonate to lift the pH to an active level because the formula I have arrived at has only half the Sodium Sulphite.
Here is the formula I put together.
Mix in the order given
700 mls [120 F]
2.2 gms metol
50 gms Sodium Sulphite
6 gms Hydroquinone
3 gms Borax
2 gms Potasium Carbonate [Substitute sodium carbonate if you need to]
Water to 1000 mls
Final pH about 8.9
For my initial tests I halved all the above to make 500 mls
With Efke 100 try 1+1 @ 70 F for 7 minutes. Rate the film at 50 iso.
Of course determine your own film speed if this works for you.
My initial test images are very promising.