1. what's the shelf life of the developing solutions (developer, bleach, fix etc)?
The problem is that there are developer kits available that will (chemically) suffice for two 30
meter rolls of 16mm film, but the tank needs that amount to develop just one 30m roll of film.
So obviously it is desirable to develop two films right after each other, reusing the chemicals.
The problem is that the developing process takes roughly 60 minutes, which means that the
solutions will have to wait for that long until they are going to be reused. How critical is this?
I read it especially critical with the bleach bath, but this can be done by preparing an additional
bleach bath (for which the chemicals are obtained quite easily, as long as no chromate is used).
2. The processing times usually are given for full immersion of the film material...
What if I built a processing tank myself that does not use total immersion, but used
intermittent immersion (e.g. rolling the film through the developer solution on a large spool)..?
What factor do i need to prolong the development times? Are there any drawbacks
of intermittent immersion vs. full time immersion?
3. Some sources suggest the use of potassium permanganate and sulphuric acid as bleach
bath, others suggest potassium permanganate and sodium bisulfate... while the "original"
thing seems to the the potassium chromate based bleach bath. What's the real deal, what bath
4. Sodium bisulfate is available through pool stores as "ph-minus" for lowering the pH level
of the pool water. Has anyone checked with the manufacturers of this stuff whether this is
pure enough, or has anyone even tried this for processing?
5. What's the minimum suggested speed of a continuous processing machine that uses several tanks?
My idea was to build such a processing machine with minimal tank size so 800 ml or maybe
1600 ml of processing solution will suffice for each bath... Is this possible? I have some bad
feeling especially about the transitions from bath to bath, as the film might start to dry there
Edited by Marc R., 21 August 2007 - 04:08 PM.