Re-photographing a photograph through a glass screen that has 55 to 130 lines per square inch, vertically and horizontally {photoengraving}|, makes a negative that has very small dots.
process
Zinc or copper sheets {plate} with film emulsion receive negative. Light shines on plate to deposit silver. Developing plate and washing with acid dissolves zinc or copper at locations that have no silver. A roller applies ink to plate. Machines {printing press} press paper onto plate, to make heavy, medium, and light dots.
color
Color prints require yellow, red, blue, and black color plates {four-color process}. Art magazines use six plates and colors: yellow, red, blue, black, green, and white.
Practical Affairs>Machine>Kinds>Optical>Copying
7-Machine-Kinds-Optical-Copying
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Date Modified: 2022.0224