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The Making of Picture Book Illustrations: What is Preseparated Art?

Key Plate, Overlays, and Flat Tints

Nana Upstairs & Nana Downstairs 1973 front cover (Click to Enlarge)


Tomie de Paola’s Nana Upstairs & Nana Downstairs was printed with three colors of ink. The original artwork used to produce the book consists of three color separations for each illustration; each set of separations includes a drawing in pencil that is supplemented with two overlays. Every artist had a slightly different approach to making color separations, but this technique was one of the most common.

The pencil illustration was executed on thick drawing board. This piece of artwork is known as the key plate. The key plate is the separation that contains the majority of the detail in the image and is almost always printed in black.1 Because this is a pencil illustration with continuous tones a halftone screen was used in the creation of the printing plate. The black text was added to the illustration to print on the same plate.

Additional colors are added through the use of two overlays. An overlay is an additional piece of copy meant to "lie over" the key plate. They were most often executed on transparent sheets of a thin plastic called acetate, as here, or on thin sheets of paper. By attaching the overlay on top of the key plate the artist could identify areas where color should be added.2 Each overlay was used to make an additional printing plate. Note that both overlays are executed in solid black ink. This makes it easier for the camera person to photograph these pieces of art. The actual color to be printed is simply indicated in text on each piece. In this example there is one overlay for pink ink and another for 30% ochre.

30% ochre is a flat tint of the printing ink ochre. A flat tint is a lighter tone of printing ink achieved by replacing the solid tone with an area of uniform halftone dots. These tints were generally available in 5% or 10% increments; the smaller the percentage, the smaller the dots and the lighter the tone. Even though halftone dots are used, art that employs flat tints is considered line copy because a screen was not required while photographing the art.3

In this way Mr. de Paola has created three pieces of copy that can be combined on a printing press to create a piece of color artwork. Only one piece of copy requires halftoning to capture continuous tone, and no color separation is required from the printer. As a result, this book was significantly cheaper to manufacture than it would have been if the artist had simply created a single painting.

1. Pitz, Henry C. Illustrating Children's Books: History, Technique, Production. New York: Watson-Guptill Publications, 1963. Print. 172

2. Shulevitz, Uri. Writing with Pictures: How to Write and Illustrate Children's Books. New York: Watson-Guptill Publications, 1985. Print. 217-220

3. Zelinsky, Paul. "RE: EJK experience." Message to Paul Mostrom. 24 January 2016. Email.