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Kodak has found out why high-sensitivity photo and X-ray film sometimes fogs
for no apparent reason (GB 2359973). In dry weather, the film becomes
electrostatically charged when it is rewound at speed, or when pulled quickly
from lightproof packaging. The film then discharges via metal in the camera,
creating electric currents which cause blemishes on the developed image. So
Kodak is now adding a transparent, conductive layer to the film base.
Polyalkylene glycols, extruded at the same time as the polyethylene base, form a
micrometre-thick conducting layer on the side opposite the light-sensitive
emulsion. So the base never has the chance to charge up.