Kevin O'Brien (kob@paradise.net.nz)
Sun, 21 Feb 1999 21:08:24 +1300
Reversal processing is simpler and less fussy than all the formulations
suggest. Most are very similar; the variations are probably result more from
commercial copyright reasons than any other. One doesn't need to be a rocket
scientist to do it, it's cheap and most of us have suitable chemistry
already. A large part of the process can be carried out in dull room light.
The aim for most here is to make what would be bad slides but what, when
enlarged, would make thick, dense, long scale negs (just like we would have
liked to have done in the camera). From experimentation, confirmed by the
manufacturers, fast films - ASA 400 - can be reversed but are too soft for
slides. Films like Pan F (50ASA) give brilliant slides but we have to
reduce them so might as well take the bonus of a faster film to start.
Another bonus- the reversal process gives finer grain from a given film
because of the solvent added to the first developer. You may need to
experiment with the film speed: minimum exposure leaves maximum density on
the resulting transparency so you may gain a stop or more.
Basic steps:
(0. Optional formalin hardening bath.)
1. Develop right out in developer containing a very weak silver halide
solvent.
2. Dip rinse
3. Bleach out developed silver with acidic bath which also stops
development.
4. Clear bleach stains.
4. Render remaining silver halides developable.
5. Re-develop
6. Quick rinse
7. Quick fix/harden
8. Wash
1. First developer - The only control step.
A choice of developers is possible The aim here is full development: Ilford
PQ Universal 1+5, Bromophen, Rodinal (paraphenyldiamine), MQ, ID36, D158,
D72, Eukobrom, Paterson Universal. Strength 3-4x regular film use.
Add plain hypo 6-50ml of 25%soln i.e 2-12g/l of working developer. Faster
films need the higher amounts. Ilford recommending 12g/l for FP4 plus or
DELTA 100.
The time in the developer is important as a vigorous development is needed
and it is a race against the hypo which is trying to eat away the undevelope
d silver. The longer the development the softer the result. Changing the
quantity of hypo that would make a good slide also alters the gradation.
2. Permanganate bleach
Use your regular sulphuric or make:
Pot Permanganate 2g (½l level tsp)
Sod bisulphate 20g (rounded tbsp)
Water to 1l
It is possible to over bleach - but difficult. This bleach has only one job
to do - eat away the developed silver so it can be washed out. Once the film
has been in the bleach for 30s white light can be turned on and the rest of
the process carried out.
3. Clearing use 5% sodium sulphite or 3% sod metabisulphite (the smelly
alternative with the sharp odour).
4. This stage can act as rinse for the previous one. Keep the film wet
remove it from any spiral and expose both sides for at least 1 min to a
fluorescent light or 150w bulb at a distance of approx 30cm or 1ft. Don't
splash the bulb! Avoid sunlight - you don't want to do printing out at this
stage. Plenty of light to fully fog it - but not too actinic does the trick.
Chemical foggers work but no one recommends them. They are also very
hazardous to have around a working darkroom; a little bit of contamination
could cause a lot of regretted spoilage.
5. Re-develop in your regular paper or film developer (not lith or other
alternative process developer). Dektol 1:2 works well.
7. Rapid acid/fix hardener for regular recommended time. The time here is
mostly for the hardening. Don't over do it as bleaching may occur.
8. Final wash. Careful with drying, the film has had a hard day and you
could give your new trannies a beautiful crinkle on their emulsion. Don't
use the hair dryer. A little wetting agent or dish wash and hang to dry.
Keep the temperature as even as possible throughout all steps to avoid
reticulation and frilling, ideally within ±1ºF. If temperature control is a
problem try hardening the film with a preliminary bath of 2% formalin. The
rinses can be minimal, it seems to make little difference but it keeps the
water useage down and reduces the risk of physical damage to the film.
Stainless steel film holders and reels aren't recommended by some but it
seems again to be inconsequential.
Some experimentation is necessary to match your film/developer/hypo
gradation requirements but that should be fairly easy.
Best practical summary is that by Ilford:
http://www.frii.com/~rkymtmem/reversal/ilford.html
Kevin O'Brien
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