Figure 10. Using roll attachment with partially completed transparency
neath to complete the presentation. In this way, the original partial
transparency may be re-used as often as desired.
17. Carbon-Coated Film
Use a sharp pencil or a stylus on the emulsion side of carbon-
backed film to obtain brilliant white lines against a dark background
on the screen. Lay the film directly on the projection stage, or mask
it in one of the following ways :
a. Mount the film to a single mask with masking tape.
b. Insert the film between the two parts of a double cardboard cut-
c. Insert the film between a sheet of clear plastic and a single
mask. In this case, be sure that the plastic sheet serves as backing
and that the emulsion side of the film is exposed for writing.
Use a series of overlays to show the construction or breakdown of
such things as business forms, electronic circuits, biological structures,
logistic concepts, and machinery. Make up, number, and assemble the
Cut out symbols or disks of colored plastic and use them to spot
locations. Change or maneuver the locations during the demonstra-
tion by using the rubber-eraser end of a pencil to move the symbols or
disks from one position to another. Symbols may represent build-
ings, vehicles, traffic markings, elements of terrain, guns, bursts, per-
sonnel, or other figures and objects.