2 Chapter 1
1.2 PRINT BASICS.
As previously mentioned, a blueprint was originally a print comprising a dark blue background with white
lines (Figure 1.1). Traditional blueprints have largely been replaced by more modern, less expensive
printing methods and digital displays. Indeed, today over 95 percent of businesses are producing prints
generated with computer-aided drafting (CAD) software and printed on large printers. The most com-
mon methods used to reproduce drawings are outlined below:
Diazo-Print Process.
In the early 1940s, cyanotype blueprints began to be supplanted by diazo prints or whiteprints, which
have blue lines on a white background. These drawings are also known as Ozalid or blue-line prints. The
diazo process is an inexpensive method of making prints from any type of translucent material. It is the
result of a printing process that utilizes ultraviolet light passing through a translucent original drawing to
expose a chemically coated paper or print material underneath. As the light does not pass through the
lines of the drawing, the chemical coating beneath the lines remains unexposed. The print material is
then exposed to ammonia vapor, which activates the remaining chemical coating to produce the blue
lines. Diazo prints can also be produced with black or sepia lines.
Figure 1.1 Illustration of traditional blueprint.