PHOTOGRAPHY-42

FILM PROCESSING … CONTD.

PHOTOGRAPHY-42

Soon on nearing completion of the time chosen for ‘developing’, the developer is retrieved to a container or drained off if in diluted state and the stop bath [ Acrtic acid is fed through the tank mouth. Please recall that the deveoper is an alkaline liquid; so neutralizing the alkalinity can make the developer inert . So Acetic acid is used. All inorganic acids can eat away the film , never use any of them for ‘Stop bath’ function.

Between every successive chemical step, it is wiser to use fresh water to rid the film of any chemical medium to avoid contamination of the next solution in line.

THE FINAL [CHEMICAL] STEP = FIXER  [Sodium thiosulphate]

The role of fixer is rather indirect. How, the so-called ‘fixing’ is simply removal of all unused  silver halides [segments unaffected by light] by precipitation as silver thiosulphate and the metallic silver segments stay as image areas on the film. In about 3 minutes a fixer can remove all unused halides but it is better to permit longer interaction to remove all unused halides. Otherwise they can stay on film and get slowly affected by light and spoil the image clarity.

The true final step is thoroughly washing the film in at least 5-7 washes in fresh water by thorough agitation of the tank.

Finally, the film is left to dry in cool shade of the bath room to prevent dust gathering on film.

Fine nuances in handling films for film processing

All amateur tanks are provided with 1 / 2/ 3 ‘take-up’ spirals for keeping the film rolls in one, two or three tiers vertically piled up before the tank is closed by the light-proof lid. Loading of film[s], placing the lid  are done in total darkness , while the film process is carried out in a normally lit area with facility to drain wash water after every step. One has to learn the mechanics of loading the film into the film spiral so as to feed the total 5 feet and 8 inches of 35 mm films or about 3 feet long 120 format films in their spirals. The loading process requires co-ordinated turns of right and left wheels alternately , holding the film at the edges by the thumb on the respective sides . The ‘hold’ by the thumb should be relaxed on the corresponding side where the wheel is turned forward, so that the film climbs through the groove and moves inward free of difficulty in entry. It is advisable to use spoiled film lengths to practice the mechanics of film loading . Upon the completion of loading , the tail most end of the film is cut from the take-up spool so that the spiral, holdimg the film is easily placed in the tank.

Before starting the chemical treatment, it is better to wash the film at least thrice with fresh water held at processing temperature. This ‘pre-wetting’ helps to remove all antihalation dye rom the film and also helps full contact between film and chemicals as the film is aready wet. Dry surfaces suffer from airbubbles clinging on to dry film when unsoaked film comes in contact with chemical solutions.

Always cultivate the habit of keeping the tank tilted at 45^o angle to help the  ‘escape’ of air as the liquid enters through slope on the lower side. If tank is kept vertical, liquids face resistance from air gushing out of the tank.  Always a thermometer [Celsius scale],  watch / clock to note the time for competion of a step and sufficient water for washes are kept near by to avoid any lapse in concentration.

Keep ready 2 clothg clips to suspend films for drying . A clip on the lower end of the film length can keep the film ‘open ‘ without coiling up and help even drying.

More to follow

K.Raman