Jet Antihalation Backing and its Removal from Films during Processing

Removable jet-black backing, commonly referred to as rem jet, is coated on the support side of many color films to absorb any light that is not absorbed by the emulsion and support layers during the photographic exposure. Without rem jet, some light would be reflected at the support-air interface. This reflected light could expose additional silver halide in the emulsion, giving rise to halation. The backing also provides antistatic protection, some lubricity and some protection from scratches. Rem jet is a dispersion of carbon black in a polymeric binder, a dibasic half ester of cellulose acetate. On passing through solubilizing solutions at pH values above 8, the polymer becomes soluble in water and this property is utilized to remove the rem jet in processing. Also important is the suppression of solubility by a high concentration of salts. Backing removal includes submerging the film in an alkaline solution of high salt content, rinsing with water, and buffing away the remaining rem jet. Chemicals and water with few impurities must be used, and rem jet must be removed carefully and completely at the proper point in the process. A particular rem-jet-removal system that is in general use is discussed in detail because it has many necessary and desirable general characteristics. Several other proven rem-jet-removal systems are discussed briefly. A new approach to rem-jet-removal equipment is also discussed.

Print ISSN

0361-4573

Published

1971-07

Content type

Original Research

DOI

10.5594/J00826