Yesterday I brewed another batch, “C-27” and it turned out to be very close, I don’t think home brewing can get any closer!
CD4 was increased to 5.3 g. Because of more acidic developing salt potash has to be increased as well to 34 g/ litre
Potassium bromide was reduced in increments, 1,4 g/Litre seems to be the optimum amount.
Potassium iodide was reduced again to 1.2 mg/Litre.
Compared to “C-26” HAS was reduced to 2 g/Litre, and again a pH adjustment was necessary (grumble…) This time I increased the Sodium bicarbonate (Baking Soda) in increments up to 1.9g/litre lo maintain a pH of 10.16
Developed clips where near perfection, high density regions as well as low density regions. Full film speed is reached, with steady going range of contrast. Because of beneficial influence of KJ in an amount of 1.4mg/litre in a former run, I just topped again 0.2mg/litre to the existing 1.2mg.
The Jobo is prewarming now, but because of excellent former clips I dare to jump into the cold water and have filled a tank with 5 Films 5 x 135/27exposures (equal to 4 x135/36 exposures)
This is my final developing solution: “C-27”
800ml tab water
1 ml A905
1.9g Sodium Bikarbonate
3.5g Sodium Sulphite
1.4 g Potassium bromide
1.4 mg (!) Potassium iodide
Up to 1 Litre,
Measured pH is 10.16 at 25°C. As stated somewhere above the ph meter is a cheap one, so there may be a variance, suppose it’s around .03 till .05
BUT whatever you do, pH has to be above 10.11 (measured with my unit 10.13), there is absolutely no chance to get a proper developed film with lower pH! Red will suffer badly!
Therefore be accurate if scaling the ingredients, especially Bicarbonate and Potash, HAS and CD4. This formulation is intended to work without pH adjustment, that’s why I included the bicarbonate buffer. If proper ph measurement is available you may vary a bit, but have to readjust the ph again.
Uuups … Just measured the 5 films out. There seems to be a temperature inconsistency. It’s a different about 2/3 stops weather multitank 2 (with its volume of 270 ml) is used or the multitank 5 filled with a whole litre. Seeing this, I remember why I preferred the wet prewash for so long time…
Anyway, a multitank 2, combined with a dry prewarm and about 250 ml (one film) of developer works definitely fine. The processors water jacket temperature is set to 38.4°C since ages; have to measure the difference of the temperature, after a minute or so, direct in the drums. Sadly my holidays are over, prints have to wait too.
Regards from Germany,
Last edited by stefan4u; 10-16-2008 at 05:50 PM. Click to view previous post history.