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1947-48 Theatre Catalog, 6th Edition, Page 268 (254)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 268
Page 268

1947-48 Theatre Catalog, 6th Edition, Page 268


V f \ / \.. Light hitting surface break is deflected

Light ray : / \ through opposite surface

paint glows { # (NOE \\ / \ /,."//H1\\\ \\

45" groove is a band of light when

\\ seen directly / (u E h u groove hasaThin highlight \\: from any angle //

Square groove has brilliant sides only



FIGURE 8-A variety of techniques are available to produce the different effects. A painted design glows with a diffuse light, but actual cutting 01 the surface of the plastic produces sparkling highlights. An engraved line appears most brilliant, seen directly, if given a V profile. ILU profile reflects a thin highlight from any angle. Square-cut grooves will have only sides that are brilliant.

FIGURE 9-]! the edge through which the light enters the sheet is colored with a transparent dye, a white-painted. or engraved design on the sheet will be similarly colored. There are endless variations of this process. The back surface of the sheet reflects the most light, but the reduced brilliance of front-surface reflection from the back sheets may be useful in designs where brilliance is not needed.

end dyed red

white design

// \\ /// \\\\ <- red light reflected from paint

FIGURE ill-Painting in light is produced by engraving parts of the design on successive sheets of plastic so that, when bound together, an entire scene is represented. The edge of each sheet is colored as desired, and when edge-lighted the complete scene appears in depth, color, and light. It is otten desired to provide some sort of backing (even a sheet of paper) for an edge-lighted panel.

blue dye

ellow d e y red dyz


Part ofa scene engravod on each sheet of Plexiglas



ever, the design becomes luminous in red light while the unlighted background remains uncolored and appears gray.

Radiant Walls

Another application of this principle

is in interior decoration to produce'the so-called "radiant walls}, The surface of the wall is covered with a sheet of Plexiglas in which an appropriate design is painted or engraved (Figure 11). Light is given off from the surface covered by this designeenough light to provide an entire room with soft, low illumination.

The entire surface of the plastic sheet cannot be covered by painting or engraving and still be edge-lighted satisfactorily. The design must be intermittent to allow the light to refiect back

and forth between the surfaces, other- wise the light is largely diffused from the sheet through the portion of the design nearest the source and the balance of the sheet will be very dimly lighted. In general, the less decoration, the more intensely the sheet is lighted.

The color of a painted surface also bears a relationship to the light transmission from a sheet. When light strikes a painted pattern, some is absorbed, some escapes from the sheet making the design glow, and the rest continues to travel within the plastic. The more light that is absorbed by the paint, the less there is to be reflected out to illuminate the design and to reach other parts of the design. Paint applied to a panel, therefore, should be fairly light in color) preferably white.

The area of decoration that can be adequately illuminated varies directly with the sheet thickness. For example, a 2-inch disk painted on ]/16-inch material will be poorly lighted in the center, but when painted on 3/8-inch material it is evenly illuminated throughout. Obviously, the thinner the sheet, the closer the two reflecting surfaces and the more frequently the light rebounds between them (Figure 12). Hitting at shorter intervals all available rays will be diffused sooner in the thinner material.

Light which is not diffused from a design in a decorated sheet normally escapes from the edge opposite the source of light. To prevent loss of this light, provision should be made to reflect it back into the sheet (Figure 13). In theory, this is done most effectively by mirroring that edge of the sheet. However, in most cases, the best method is to paint the edge with opaque white paint. By this means the light is rediffused and a large portion is turned back into the sheet.

One of the difficulties in edge-lighting designs is the securing of sufficient illumination over a large area. There is no one solution to this problem. Each

FIGURE lleAnother application of this principle is in interior decoration to produce radiant walls. The wall is covered with an appropriately engraved sheet of the transparent acrylic plastic.

f*Opaque background

Light for room


Design engraved or painted /,


1947-48 Theatre Catalog, 6th Edition, Page 268