Paper, Photographic

a sensitized material, consisting of base paper (backing) coated with a layer of photosensitive emulsion.

This layer is a suspension of silver halide microcrystals (from 0.5 to 0.01 microns and smaller) in an aqueous gelatin solution. The emulsion is applied to the backing in a thin layer and then dried until air-dry. The thickness of the dried layer is 10-15 microns. Depending on the type of photographic paper, the emulsion is applied either directly to the raw paper material or to a paper backing precoated with a layer of barite. This layer consists of barium sulfate micro-particles with gelatin as a binder.

Photographic paper (black-and-white and color) is classed in two groups—general purpose and technical. The first group is intended for amateur, professional, and artistic photography, and the second group is intended for photographic work in various technical fields.

General purpose photographic paper is made for projection and contact printing, and the technical paper is intended for exposure, registration, and copy printing. General purpose photographic paper is available in glossy, mat, and semimat finishes; grades of paper are soft (no. 1), standard (nos. 2 and 3), contrast (nos. 4 and 5), and high contrast (nos. 6 and 7); photobacking densities (thicknesses) include cardboard (240 g per sq m), semiboard (180 g per sq m), and thin (135 g per sq m); surface micropatterns may be smooth or textured (embossed); photobackings are white and cream-colored. General purpose photographic paper is packed in rolls and format sizes (from 6 x 9 cm to 50 x 60 cm) in packages of ten, 20, 50, and 100 sheets.

Technical photographic paper has a greater range of qualities (photosensitivity and gradations) and uses. It is classified as extremely sensitive paper for recording oscillographs, electrocardiographs, and phototelegraphs, and paper for the rapid copying of documentation, including reflex paper, photostats, photographic tracing paper (on a transparent backing), and “Tekhnokopir” and “Kontakt” paper.

Technical photographic paper is produced mainly on a thin photobacking (80-100 g per sq m) in 36- to 1,000-mm wide rolls and in different size sheets.

Color photographic paper is intended for contact and projection printing of color photographs from color negatives.