The Process of Press
Translation to print involves a process similar to rubber stamping. Printing plates are inked and the image is transferred to paper by means of pressure. But how exactly are these “stamps” created?
So Many Hoops to Go Through
A printing press cannot directly reproduce a replica of an image. Instead, printing involves a process of translations that make the image compatible with a press.
The Halftone Process
Digital photos or files are transferred through the halftone process. Most imagery contains shades of one or more colors, but a press prints all or nothing values. Halftone is the solution. One image is broken into thousands of tiny dots of varying sizes, larger and closer together where the image is dark and smaller and farther apart where the image is light. These dots are usually so small that they require a magnifying glass to see. The contrast between the dots and the white paper they are printed on creates an optical illusion. The eye does not perceive the dots, but rather a continuous image of varying tones.
Each press sheet, whether one page or many, is translated to a metal plate. A chemical process is used to etch the negative film image to the metal printing plate, resulting in the positive values. Since one plate covers only one color, an image with 4 colors requires 4 plates to make! Thankfully, pages with more than 4 colors can be still be printed with 4 plates, as all color wheel colors can be composed of cyan, magenta, yellow, and black. The semi-opaque property of ink allows halftone dots of different colors to create even another optical effect—full-color imagery – while using only four colors to do it all.
The last translation is to paper. Finally, plates are wrapped around cylinders that rotate as the paper is fed through the press. Mixed ink is applied to the cylinders and is “pressed” onto the paper with the design the plate has etched. The process is both highly mechanical and chemical, using precise application of specific substances. Each plate can very rapidly print on thousands or even hundreds of thousands of sheets!
Using the halftone process in concordance with using multiple plates can create a full-color representation of an image in print. If the translation were any less chemical or precise, it could be considered an art!