d. There are many processes used to make
intermediates and prints. They an be classified as
either negative or positive contact processes or
Contact processes require a
temporary use, to include expedients. The subject
transparent or translucent original. Optical copies
matter of this subcourse applies particularly to the
can be made from opaque originals. They are usually
frame structures used in a theater of operations (TO).
more expensive and introduce more distortion.
As an engineer officer, you may be expected to take
charge of this type of building operation.
(1) Negative contact processes.
(a) Blueprints. A blueprint is
made by placing a tracing (transparent or translucent
original) in contact with a sensitized paper and
exposing the paper through the tracing. When the
a. Basic to the successful accomplishment
paper is developed, the unexposed portions where the
of any building construction assignment is the ability
light is blocked by lines on the original remain white,
to read architectural drawings or prints. It can be
while the exposed portions turn dark blue. This
extremely difficult for an individual to describe the
produces a print with white lines on a blue
size and shape of a simple object without a drawing
background. Blueprints, in general, have better
of some kind. For example, if an architect designed a
contrast than other commonly used processes of
simple structure, it would be difficult to convey his
comparable cost but the wet developing process
idea to the person who is to fabricate the structure
causes some distortion, and marking the prints is
without a drawing to show the shape, size, and
spacing of members.
(b) Brownprints. The brownline
b. Drawing or sketching is the universal
print process (often called Van Dyke) is similar to the
language used by engineers, technicians, and skilled
blueprint process except that the paper is transparent
craftsmen. Whether this drawing is made freehand or
and exposed areas turn brown when developed. This
by the use of drawing instruments (mechanical
yields transparent lines on a brown background.
drawing), it is needed to convey all the necessary
Brownprints are frequently used as inter mediates
information to the individual who will fabricate and
producing a print which has blue lines on a white
assemble the object whether it be a building, ship,
background and called whiteprint.
aircraft, or a mechanical device. If many people are
involved in the fabrication of the object, copies will
(2) Positive contact processes.
be made of the original drawing or tracing so that all
(a) Ozalid prints. The ozalid
persons involved will have the same information.
process is a contact process like blueprinting but the
c. Drawings are normally classified as
unexposed areas of the sensitized paper turn blue
original drawings, intermediate or reproducibles, or
when developed in ammonia vapor, producing blue
prints. The original drawing is the one produced by
lines on a white background. These are called
the draftsman. An intermediate is a copy of the
blueprints. Papers are also available which yield
original which is used to make prints.
black lines (called blackline prints).
intermediate is used to avoid the risk of damaging the
development in this process is dry, causing less
original or because the original is not suitable for the
distortion than the blueprint process, but the contrast
type of reproduction process used for the making of
is usually not as good. These are normally used for
prints. Prints may also be made directly from the
original without using an intermediate drawing. A
print is a working copy to be used on the job.
produce ozalid-process prints but
which project and reduce the