Chromolithography

Adapted from Wikipedia: http://en.wikipedia.org/wiki/Chromolithography

Chromolithography is a method for making multi-color prints. This type of color printing stemmed from the process of lithography, and it includes all types of lithography that are printed in color.^[1] It replaced coloring prints by hand, and eventually served as a replica of a real painting. Lithographers sought to find a way to print on flat surfaces with the use of chemicals instead of relief or intaglio printing.^[2] Depending on the amount of colors present, a chromolithograph could take months to produce. To make what was once referred to as a “chromo”, a lithographer, with a finished painting in front of him, gradually built and corrected the print to look as much as possible like the painting in front of him, sometimes using dozens of layers.^[3] The process can be very time consuming and cumbersome contingent upon the skill of the lithographer.

Process

The process of chromolithography is chemical, because an image is applied to a stone or zinc plate with a grease-based crayon. (Limestone and zinc are two commonly used materials in the production of chromolithographs.) After the image is drawn onto stone, another stone is inked with oil based paints or greasy pens, and pressed against the stone containing the image. A different stone is required for each color, and each color must be applied one at a time. It was not unusual for twenty to twenty five stones to be used on only one image.^[4] Once the colors have been applied, the stone with the complete colored image is pressed against a sheet of paper. Each sheet of paper will pass through the press as many times as there are colors in the final print. In order for the prints in progress to avoid being covered over by the next color being applied, each print must be precisely ‘registered,’ or lined up, on the next colored plate.^[5] A coating of gum and weak acid solution is applied to the plate, because the solution helps the grease drawing adhere to and penetrate the plate while causing the blank areas to repel the printing ink. The plate is then dampened, inked, and then passed through the press along with the paper receiving the impression.