Theatre Design & Technology - Oct 1969 - 19

Thermoformed Plastics On Your Stage
ROBERT G. DUNTON, JR.
Concord ia College
"Since modern aft is eminently constructive and plastic, proposing even 'or painting the principles of architecture. it IS onl logical that \e should find its
final expression the theau€ take form in settings
'vvhich are architecturally constructive and plastic. '

Ever since Adolphe Appia. in the late 19th
and early 20th centuries. advanced his
theories in support of the three dimensional
stage setting. the stage designer and technical director have been confronted with the
problem of creating plasticity In a setting.
Because the term "plastic" has been initimately connected witll stage settings since
Appia's introduction of the concept, it
has always seemed particularily ironic to
me that designers and technical di:ectors
have made little use of modern plastics in
the theatre. Admittedly, plastics have been
used to some extent in special appl ications,
and plastic ornament is now available from
commercial sources, but plastics ha e never
been widely used by designers or technical
directors. It is the intent of this article to
show that plastics have inherent advantages
1 Walter Rene Fuerst and Samuel J. Hume. Twentieth Century Stage Design (originally published by
Alfred A. Knofp Ltd .. 1929, reprinted by Dover Pub.
lications, e'.\" York. 1967). p. 50.

Straight vacuum forming (tefe), and drape
forming (right). Illustrations from "Thermoforming" by David R. Zelnick, Ii) MODERN
PLASTICS ENCYCLOPEDIA (Nelv York:
McGraw Hill, 7967).

for use in the theatre, and that plastic materials can be inexpensively formed for use
on stage.
Why use plastics on stage? I do not intend
to discuss the design possibilities of plastics in terms of color, translucency, strength
or light transmission characteristics, all of
which deserve intensive study bydesigners.
Instead, I want to discuss the advantaaes
of plastics in the cost and rapid reproduction
of three dimensional material.
Are plastics cheaper? Yes, given limitations
of size and man hours for production. Certainly plastics are not cheaper than paper
mache or carved woods, but consider the
mall hours for reproduction. In producing
paper mache or wood objects, each object
must be modeled just about individually and
these processes are usually somewhat messy
and time consuming. When producing plastic objects, (hereafter referred to as meaning thermoplastic materials), a si milar amount
of time and effort must be expended in
preparing the original mold, but detailed
reproductions from that mold can be produced at the rate of at least one per minute.
The proprietary product Celastic (which is
itself a plastic material) 2 makes a good
2 Cefastic is a thermosetting plastic, i.e. after the
plastic has been formed its shape cannot be changed.
Thermosetting plastics are distingUIshed from thermo
plastic materials whose shape can be changed after
forming by the re·application of heat. The plastics
discussed in this article are of the latter type.

Plastic sheet.

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THEATER DESIGN AND TECHNOLOGY

OCTOBER,1969

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cost comparison. Low-cost plastics such as
styrene 3 cost approximately $.50 to $.70
per square yard while light weight Celastic,
excluding
solvent, costs approximately
$1.50 per square yard. There is some loss
in trimming the plastics but the significant
cost differential should be apparent.
Plastics are also lighter than most other
materials used for three dimensional stage
effects, a lot less messy to use, and easy
to attach to most materials by the use of
masking tape or glues.
It should be noted that the term three dimensional may be misleading. The thermoformed product does not have the solidity
which we normally associate with three
dimensional objects, i.e. when the thermoformed obj ect is viewed from the back it
appears simply as a negative version of its
front view. Or when molding a bottle we
could only form one half of the bottle unless we attempted to join two halves (a
rather difficult problem though it can be
done). A better term for most uses of
thermoformed materials might be "basrelief. "
What is thermoforming? Thermoforming is
the relatively simple process of heating a
plastic sheet, then forming it to the shape
of the product by either a differential air
pressure or mechanical means. There are
many operating techniques used in the
process, but that most suitable to the work
of the technical director is drape vacuum
forming. This process requires the least
equipment and enables the technician to
work with a positive mold which is easier
to construct than the negative.
The vacuum forming machine need be only
large enough to use standard sized plastic
stock and as large as the maximum size
object you intend to produce. The Mattei
Vacunform Kit, a "toy," will form objects
approximately 2" x 3" in size and might
be used for the construction of jewelry by
the costumer. On the other hand, C.B.S.
Television forms completely detailed flats up
to 4' x 12'.
Vinyl
is
generally produced In both
20" x 50" and 21" x 51" sizes. Styrene
is
often
produced
in
20" x 40",
3 Styrene, admittedly, IS not the best material for
stage use. It is somewhat fragile and does not take
stage paints exceptionallv well, though consideration
might be given to the use of solvents in etching its
surface for better paint adhesion. Having used sty·
rene in several productions which did not have extended runs, (4·8 performances), I have had no prob·
lems with it, though the paint has now flaked off of
materials used several months ago. One problem was
encountered with the initial painting, on areas where
grease or oil had apparently built up on the surface.
It was found that lightly sanding these areas and
repainting solved the problem. The best plastic for
stage use currently would probably be rigid vinyl,
which is somewhat more expensive than styrene.

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