Rigorous E-6 processing
Has anyone done detailed experimentation and documentation using 6 bath E-6 processing? Would like to hear some stories from the people in APUG. About a year ago, some of us are tired of inconsistent E-6 quality from the photolab, so we folks in Singapore are trying to get E-6 processing back into the good old days of the Kodak's Q-lab standards by processing ourselves.
We purchased the following equipments:
1. Fujihunt CR-56 (E-6) reversal chemicals
2. X-rite 892 densitometer with status A trasmission reading ability (new lamp and new calibration traget)
3. Kodak E-6 control strips
4. pH meter up to 0.02 pH units accuracy (with calibration buffers)
5. Hydrometers for density measurements
6. Theromocouple for temperature measurements
7. Individual cylinders for different chemicals used for dilution purposes
8. Jobo CPE-2+ and Phototherm sidekick processors
The results of our slides looks great to our eyes, many claimed it to be better than our existing photolab. However, our control strips did not hit within the control limits of processing when reading using the densitometer. Control strips were also sent to the photolab to determine their E6 processing standard and the lab was not in control limit either. We did tweak a bit with the dilution of the colour developers and the reversal bath, the timing of the first developer and starter concentrations (we use mix fresh for every E6 run). However the LD, HD and Dmax readings were a bit off. The blue reading seemed to be consistently below that of red and green for LD, HD and Dmax.
LD readings deviated up to 0.08 units (control limits tolerances were 0.05 units)
HD readings deviated up to 0.15 units (control limits tolerances were 0.08 units)
pH meter results (after dilution before development):
First developer was 0.1 pH units above the tolerance (Recommended dilution and 7ml/L of starter instead of 5ml/L)
Reversal bath was 0.5 pH units below tolerance (Tweaked to 40% of the recommended dilution)
Colour developer was 0.05 pH units above tolerance (Tweaked to 90% conc. of recommended dilution and 7ml/L of starter instead of 5ml/L)
Conditioner/Pre-bleach, Bleach are in tolerance
Fixer is 0.1 pH unit above tolerance
Problems and attempted solutions:
This whole E-6 processing is a muti-variable optimisation problem. If we tweak one parameter, the other parameter may be out. Currently we do not really know what to tweak and what is a systematic way to get it into control limits. Which should be the first parameter to look into? Getting the correct pH, or tweaking the time or temperature or dilution? If anyone does rigorous E6 process, we would love to hear from you and pointers are much appreciated.