Tuesday 11 September 2012

ANTI-SCRATCH TREATMENT [Film Technology]


ANTI-SCRATCH TREATMENT 
[Film Technology]

While exposing in the camera due to mechanical trouble or during processing damages like scratches may be happen in the negative film. Unless these scratches did not eradicate before taking print, the scratches will be reflect in black colour in positive print. So it must have to be deleted. The treatment to eradicate scratches is known as anti-scratch treatment. Scratches caused by grit may possibly be cured by blowing, brushing or wiping. Scratches caused by a pressure plate or film guide becoming abrasive must be cured by rubbing the offending surface with an orange stick, soft plastic and nothing more abrasive than jeweler’s rounge. Treatment of the negative : Fine emulsion scratches may sometimes be eliminating by soaking the film sufficiently to cause the emulsion to swell and fill the scratch. Fine scratches on the cell side may be eradicated by the use of a film base polishing machine. Scratch removal is accomplished by applying controlled amount of solvent to the film base and reforming the base on a frosted glass wheel. The scratches are then removed by filling- in when the film is re run over a highly polished glass wheel. Treatment by duplication : Scratches on the celluloid side of the film may be filled during the printing stage by the use of a wet gate printer. In this process the damaged original is totally immersed in a special fluid of the same refractive index as the base while it is the gate of the optical printer. The liquid fills any scratches or blemishes provided that the emulsion is undamaged no scratches will show upon the duplicate. A last resort cure for an emulsion scratch, especially if it is near the edge of the frame, is to make a duplicate negative (CRI) or print on an optical printer, enlarging and repositioning the frame in order to avoid the scratch.



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