bichromated

-- We now come to the second stage of the process, the application of a film of bichromated gelatine to the plate.

Scientific American Supplement, No. 362, December 9, 1882 Various

The plate is slightly warmed upon a slate slab, underneath which is a water bath; it is then flooded with the above mixture of bichromated gelatine, leaving only sufficient to make a very thin film.

Scientific American Supplement, No. 362, December 9, 1882 Various

The whole operation should be carried out in a subdued light, as too strong a light would render insoluble the film of bichromated albumen.

Scientific American Supplement, No. 344, August 5, 1882 Various

At any rate, every photographer knows that bichromated gelatine is much more rapid than the chloride of silver he generally has to do with.

Scientific American Supplement, No. 362, December 9, 1882 Various

After exposure the plate must be at once developed, which is effected by dissolving in water those parts of the bichromated gelatine which have been protected from the action of light by the dark spaces of the cliché; these parts remain soluble, while the others have been rendered completely insoluble.

Scientific American Supplement, No. 344, August 5, 1882 Various

The action of the light on the bichromated gelatine forms the basis of this process.

The Building of a Book A Series of Practical Articles Written by Experts in the Various Departments of Book Making and Distributing Various

One should bear in mind that the degree of solubility of gelatine so acted on, as also its degree of impermeability — which is important in certain processes of photogravure — is proportionate to the degree of insolation; thus, when not impressed, bichromated gelatine dissolves in water heated to about from 25 to 30 deg.

Photographic Reproduction Processes Peter C. Duchochois

While wet the bichromated tissue is insensitive; the sensitizing can therefore be made by daylight, but the drying should of course be done in the dark room, that is in a room lighted by a candle or the sunlight filtered through a deep orange window glass.

Photographic Reproduction Processes Peter C. Duchochois

In proportion to the graduated density of the negative, the light acts more or less on the bichromated gelatine, rendering the latter, in proportion, insoluble and hardening it.

The Building of a Book A Series of Practical Articles Written by Experts in the Various Departments of Book Making and Distributing Various

-- Herr Albert's original plan was to apply a preliminary coating of bichromated gelatine to the thick glass plate, the film being exposed to light through the back of the glass, and thus rendered insoluble and tightly cemented to the surface; this film serving as a basis for the second sensitive coating, that was afterward impressed by the negative.

Scientific American Supplement, No. 362, December 9, 1882 Various