Fomapan 100 reversal
I've just finished to reverse a roll of Fomapan 100 (not the R version).
1) 1°st development: Rollei RPN 60ml concentrate + 240ml H2O
3) bleaching: 50ml pt. A + 150ml pt. B + 100ml H20
5) clearing: 300ml
7) 2°nd exposure
8) 2° development: same as 1)
11) wetting agent
bleach pt. A is 6g potassium permanganate in 1000ml (distilled water);
bleach pt. B is 10ml concentrated sulfuric acid 98% in 1000ml (distilled water);
clearing is 25g sodium (potassium) metabisulfite in 1000ml (distilled water).
a) I've exposed a set of 4 frames at 25,50,100,200 iso. With this procedure only the 25 iso frame is of normal density, slightly on the thin side. Fomapan 100 yields low DMax, judging from the leader. Next step: less development time or higher developer diluition (one inversion every 5 second);
b) Bleach doesn't damage the emulsion. I've not controlled the other baths' temperature but the first development. No emulsion frilling, no damage whatsoever;
c) I've NOT used a silver halide solvent;
d) the base is cristal clear (I've used a pre-wash).
How did you achieve to get the crystal clear base, while it's blue when ordinary processed ?
Sorry, I don't know.
Originally Posted by Tofek
All I know is that I'm using the 17.5 meter bulk rool of Fomapan 100 batch no. 014215-10.
Maybe the bleach is killing the blue dye? Does the film from this bulk roll come out blue when you process normally, or is it clear then too?
To my knowledge there's no chemical treatment that can "bleach" a grey or blue colored base into a crystal clear one.
Originally Posted by polyglot
I have a few questions if you dont mind answering them :P
How long was your second exposure and what was the light source/distance from the source?
Ive just done a development trying Hp5+ with the same process (except different developer), and the emulsion is very soft after the permangenate bleach (ie, if you touch it while wet it just wipes off). Is foma emulsion significantly different to hp5+?
I just don't touch anything when it's wet. I don't unspool the film from the reel. I just expose both sides of the reel (a metal one) for 1 minute each at the glow of a 21w compact fluorescent cool white light. Almost at contact with the lamp.
Originally Posted by NDP_2010
The softening of the emulsion depends also on the first developer. It's actually the high pH shift that causes damage.
If you use a more diluited first developer you'll reduce that pH shift. You must also reduce the permanganate content (aim is 0,3g in 300ml) and the acid (I use 150ml of a 1% sulfuric acid solution).
Important is keeping a relatively low temperature of 18°C (also lower) of the bleach.
I don't think Fomapan 100 emulsion is more hardened than any Ilford counterpart. The opposite can be true.
Thanks for the info. Just following up emulsion softening, i have read dichromate bleach does not soften the emulsion compared to permangenate however both use the same sulfuric acid content and thus wouldnt the pH shift be the same?
Manganese in permanganic acid does not soften anything, chrome in chromium acid crosses-link proteins in the emulsion and harden it. The softening is due to the high pH shift in both cases, the latter being "counteracted" by dichromate.
Originally Posted by NDP_2010
thanks for the information :D
another quick question; do you develop your first development as you normally would a negative, or do you add extra time for development?