MOUNTING, TRANSPOSITION AND SPACING 81shift slightly during the mounting, and an error of half a milli-
meter is sufficient to produce a poor print.
35mm Stereograms. Modern stereograms made on 35mm film
are the most easily mounted of all. The pictures are simply cut
apart, the film edge providing a positive horizontal alignment
base, or in the case of the Personal, a dual punch makes it possi-
ble to punch out both frames at once thus providing positive
separation and alignment.
Realist films may be jig mounted. A mounting guide or jig is
provided for use with heat-adhesive masks. The mask is placed in
the jig, the cut films are placed in corresponding wells which
align the film, and the films are sealed into the adhesive mask
with a heated sealing iron. The mask is then mounted between
glass slips and sealed with tape. A special cutter is provided to
insure cutting the film perpendicular to the edges.
An alternative is a cardboard mount which is almost as rigid as
the glass slide. It has accurately diecut pre-formed pockets into
which the film is slipped. As the pockets are already spaced, it is
only necessary to keep the left and right films in correct order,
slip each into its own pocket and the slide is ready for use. This
method of mounting is proving popular for both hand viewing
and projection.
Another type of mount is the Permamount. This is a plastic
base into which three channels are molded in the form of a very
squat “H.” A glass slip is dropped into the cross channel, then
the films are laid in the two end channels and another glass on
top. The whole is sealed and label provided by a die-cut, self
adhesive panel which seals the assembly into a permanent unit.
These are provided with three separations which compensate
for projection base and permit all types of subject from close-up
to distance to be projected in any sequence without adjusting the
projector control.
The Personal films are mounted in a similar way. Blank “reels”
familiar to those who have used the Viewmaster are provided.
These have accurately formed pockets into which the film is
slipped from the edge inward. Because of the blank tab at the
end of the film this may be done without touching the film. The
accuracy of alignment is extremely satisfactory, and the system so
easy that a child can learn to do it in a few minutes. These reels