Wednesday 12 September 2012

BACKING REMOVAL [Film Technology]



BACKING REMOVAL 
[Film Technology]

Many colour stocks incorporate an antihalation layer of carbon coated on to the back of the film. After softening in a pre-bath of borax [raising the PH to about] and sulphate (to prevent premature removal of carbon) in soluble carbon is removed by water jets in the backing removal units.  Rotating brushes or rotating pads scrub any remaining carbon from the film.  Care must be taken that no carbon reaches the emulsion side of the film were it will be rapidly absorbed by the gelatin. Rolls of exposed film staples together and attached to the end of the film already on the processing machine. Film then travels over guide rollers through vertical tanks for the pre-bath, backing removal, developer, stop bath, bleach, fixing and stabilizer, interspersed with washes to avoid chemical transferring from one bath to the next. See processing and   processing machine. In the final stages the film may be chemically hardened, before passing through drying cabinets and spooled into each customer’s rolls.






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