Blueprint

[1] The process allowed rapid and accurate production of an unlimited number of copies.

[3][4] Practising engineers, architects, and drafters often call them "drawings", "prints", or "plans".

Where ultra-violet light is transmitted through the tracing paper, the light-sensitive coating converts to a stable blue or black dye.

Where the India ink blocks the ultra-violet light the coating does not convert and remains soluble.

To combat this problem, printing on imitation vellum and, later, polyester film (Mylar) was implemented.

Traditional blueprints became obsolete when less expensive printing methods and digital displays became available.

The sequence is a computer file which will control the operation of the machine tools used to make the part.

In the case of construction plans, such as road work or erecting a building, the supervising workers may view the "blueprints" directly on displays, rather than using printed paper sheets.

Construction crews use software in the field to edit, share, and view blueprint documents in real-time.

These originals have significant importance to the repair and alteration of constructions still in use, e.g. bridges, buildings, sewer systems, roads, railroads, etc., and sometimes in legal matters concerning the determination of, for example, property boundaries, or who owns or is responsible for a boundary wall.