Developping of black & white films
The essential condition to obtain a good hard copy is to have a negative good. For the development of a film, one can take the advice of Jean-Yves Brégand (a french fine-art lab guru) i.e. use a stainless tank rather than a plastic tank because stainless has a greater solidity, the metal whorls avoid the problem of the deposit of bubbles on film (due to agitation). The stainless hardware is cleaned and dried more easily. As regards the development, if you decide to develop with 20°c, the temperature of revealing must be at the beginning slightly higher than 20°c to compensate for cooling due to agitation I employ a D76 formula for films exposed to the nominal sensitivity. If film is pushed, one has a rise in contrast and grain. In this case I use the revealing special ones which maintains balance between the low ones and the high lights and which avoids the rise in grain (for example Acufine™ or Diafine). Ilford Microphen allows, in the case of pushed films, to preserve the smoothness of the grain, but it does not compensate for the rise in contrast. As for the DK50, it is revealing especially conceived for the Recording film used if one wishes to have much grain (the grain significant but is balanced, distributed well well). Most of the time, I never push a film. On the contrary, I tend to over-expose to have more details in the shades and I seek my time of development in connection with the voluntary over-exposure. When one speaks about over-exposure, it is in general compared to the sensitivity given of film expressed in the ISO standard in ASA. I thus regard this data as relative and I adjust my exposure and my processing according to tests which I practise on the emulsion that I use and returned that I want to obtain. It is the beginning of the Zone-System.
Developer is simple to make and
give good results on many emulsions :
D-76(Kodak) or ID-11(Ilford)
of which here a formula:
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The genol
being not easily water soluble, to dissolve in 300 ml (hot 45°c)
a little sulphite and to it to add the genol. this one dissolved,add
sulphite. Wait for total dissolution to pour hydroquinone and then the
borax. One can prepare
with share in part of water the hydoquinone and borax then to add it
to the first solution (genol-sulphite). One can add in the volume of
water remaining a drop of surface-active agent (ilfotol-Ilford compatible
with D76) in order to improve the penetration of revealing in the emulsion
in this case, the pre-wetting is not necessary |
1) ILFORD Films
develop 1 minute more than the KODAK with equal sensitivity in D76
2) Films 120 develop 1 minute more than the 135 of the same sensitivity
3) A film developed in diluted D76 to 1+1 develops 4 minutes more than in
the revealing pure one.
In addition, it is significant to know that one can also obtain a good balance
between the high ones and low lights with the catch of sight. Thus it is possible
to break a too strong contrast while over-exposing and while underdeveloping
and conversely if one wants to increase contrast.
Examples of processing time in D 76 pure for a film 35 mm:
Times are in minutes, seconds
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Processing time in D 76 pure for a film 120:
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These times are given for an agitation of 3 shake-rotations per minute.
A lower contrast is obtained
when:
1. one develops less longer,
2. one " extends " the revealing one (dilution),
3. the temperature is lowered.
A high contrast is obtained
when:
1. one develops longer than the normal,
2. one increases the concentration of revealing,
3. one raises the temperature of the revealing one.
One can practise a development with a pre-wetting. The pre-wetting is used to humidify the gelatine in order to make it more avid of revealing. The interest is to avoid the zones of processing which one can observe on films, in particular near to the perforations (films 35mm). The pre-wetting changes the duration of revelation.
The stop bath
One should not use stop bathes of the trade: they are likely to cause zones. If one uses a stop bath based on acetic acid in aqueous solution, it must be correctly proportioned: too much extremely it tackles the plastic support and reticulates the gelatine; too much diluted it is ineffective. Average dilution is 8%. But one can do and make without it a rinsing with water twice. One then immediately pours the fixer prepared in advance and pret to be poured in a jug or a bottle with broad neck.
The Fixing bath
The fixation will be done with a fast fixer standard Ilford Hypam, diluted to 1+4, four minutes with an agitation of the same type as at the time of the bath of revealing. One will wash then film 25 minutes out of running water with a contribution of air in the tank using a " photolav"( from Jobo™). Washing is the essential stage for the archival quality of your images.
Drying
A fast passage in
an bath of acetic
acid which prevents the formation
of trails limestones, then a final washing in a water added with surface-active
agent will avoid an irregular drying.
In the absence of an automatic steam drier, the negative ones are exposed
to the free air until a complete evaporation of the water absorptive by the
gelatine is effective.
They must be suspended vertically by sparing between them a sufficient space.
A normal drying at ambient temperature in a relatively dry atmosphere, is
preferable.
It will be made in a place without dust, avoiding any change of temperature
rate too large, under penalty of seeing appearing " rings of drying ".
A hot and
wet atmosphere delays the operation and supports the proliferation of the
bacteria. If the gelatine were sufficiently hardened in the course of manufacture
or by a tanning bath, drying can be accelerated while carrying the temperature
with 40� C to the maximum but it is surer to stick to 30� C.
To expose thenegative to the direct action of the sun or an apparatus with
radiation is very risky.
The internal temperature of the gelatine being able to rise without it being
noticed. In the professional laboratories, one uses steam driers with circulation
of hot air free from dust and whose temperature is regulated by thermostat.
The slides are dried like the negative ones. In order to protect them, one
gives them sometimes a hardening bath: in this case, an activated drying does
not present the same disadvantages.
Paris 2000, © ChristopheGlaudel
for the text and respective owners for the formulas.
Acufine, Diafine, D76, DK50, Ilford, Microphen, Hypam,
Ilford, Kodak are trade marks
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