Horgan's half-tone and photomechanical processes .. . ween it and theback of the sensitive plate, thus preventing reflection ofwhite light on the sensitive film. INVENTOR OF THE ENAMEL ACID RESIST Charles E. Purton, working in Philadelphia about 1883,is said to be the first one to use gum arabic and fish glue tocoat a copper plate with and afterward carbonize the filmso as to make it acid resistant. In the Photographic News of November 4, 1881, Major-General Waterhouse described the Gamier process, in whicha copper plate was coated with a solution of two grams ofsugar and one gram of bichromat
Horgan's half-tone and photomechanical processes .. . ween it and theback of the sensitive plate, thus preventing reflection ofwhite light on the sensitive film. INVENTOR OF THE ENAMEL ACID RESIST Charles E. Purton, working in Philadelphia about 1883,is said to be the first one to use gum arabic and fish glue tocoat a copper plate with and afterward carbonize the filmso as to make it acid resistant. In the Photographic News of November 4, 1881, Major-General Waterhouse described the Gamier process, in whicha copper plate was coated with a solution of two grams ofsugar and one gram of bichromate of ammonia in fourteengrams of water. This coating was dried and printed undera positive, and dusted with an alkalin powder, when theimage showed plainly. (This was the origin of the dry-enamel process.) After which the copper was heated overa flame until it showed iridescent colors. The sugary coat-ing thus becomes hard in the exposed parts, but under thepowder it is broken, powdery and permeable to acids. Itwas then etched in perchlorid of Fig. 2.— Three-color Reproduction, Red made through a green filter. Fio 3.— Three-color Reproduction, Blue made through an orange filter. \
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Keywords: ., bookcentury1900, bookdecade1910, bookidhorganshalft, bookyear1913
