Gelatin fragile material
There are several grades of photographic gelatins : In a past still close enough, it seems that there was a range of hardness of this […]
Articles by michel.momal
Invention of the process
The light sensitivity of bichromates : In 1797, the chemist Vauquelin, who had just discovered chromium in studying various combinations, found that some of the oxygenated compounds in […]
Assembly of the composition
It’s about an operation there, which, without being difficult also has its importance for the obtaining of a good result. The purpose to be reached […]
Cleaning plates
Cleaning former coat Glass used as printing matrix for collotype having the advantage to be able to be almost reused infinitely (until accidental break), it […]
Degreasing plates
Cleaning of the plate with ammonia before the first adhesive coat : In prerequisites, glass plates will have been cleared of the coat of gelatin […]
Adhesive coat
Preparation of the adhesive coat (between glass and sensitive coat): prepare the aqueous mixture by adding a junior solution of silicate of soda or potassium […]
Bichromated gelatin
SECOND COAT – DICHROMATED GELATIN (coat sensitive to U.V.) Quantity of preparation (in cubic centimeters by square decimeter cc / Dm2) : whatever is the […]
Photosensitive gelatin
The wet gelatin is a compound very sensitive to the temperature. It liquefies in 86 ° F approximately, where from the difficulties maintaining a resistant, […]