GB202257A - Photo-mechanical process for producing bas-reliefs - Google Patents

Abstract

202,257. Monteath Photo Sculpture, Ltd., (Assignees of Monteath, F. H.). Aug. 10, 1922, [Convention date]. Embossed and relief photographs; bichromated colloid processes.-A process for producing plaque bas-reliefs, embossing dies, &c. comprises (1) producing a negative of the subject using frontal lighting and a black background, (2) producing on a glass or like support a plate of bichromated gelatine, one-eighth of an inch thick, in a warmed vertical mould, (3) printing from the negative through a mask on to the gelatine plate in daylight for two hours, (4) masking the printed portion and printing the surround through clear glass for ten minutes, and (5) developing the plate in water to produce by swelling a relief from which a plaster or like cast can be taken. In preparing the bichromated gelatine, the bichromate is added in dry powdered condition to gelatine, which has been soaked in cold water, drained free from surplus water, and melted by heat, the proportions employed being 5 grains of bichromate to 1 dram of dry gelatine. The mould in which the gelatine plate is cast comprises a glass or like backing- plate A and a flexible polished sheet of tinned steel or copper B backed by a glass or like plate C, the whole being held together along three edges by a rubber rebated frame D and on the fourth edge by a rubber parting strip G so as to leave a chamber between the plates A and B about oneeighth of an inch thick. The plates are securely held by a number of clips such as that shown at N. The mould is heated to the same temperature as the melted bichromated gelatine, and this is siphoned or poured through a flooded funnel into the mould through the aperture H or K. The temperature is maintained until the gelatine is clear and free from bubbles. The mould is then cooled and dismantled, and the plate B is stripped from the gelatine sheet; which remains on the plate C during the subsequent operations. The cast ultimately taken in plaster, wax, &c, may be bronzed, electroplated, &c. to yield any desired finished effect, or may be used as a matrix for producing repetitions in known manner, or for producing embossing dies and founder's patterns.