Theatre Design & Technology - Oct 1973 - 26

attempt to find a reason for this difference and a reason
for the instability of the Roscolar Golden Amber would
only be speculative, in light of the usual high spectral
efficiency and stability of amber. (Compare the unexposed
sample of amber with the spectral distribution of a 500watt incandescent lamp, Figures 2.00 and B.)
Among the lavender samples, a qu ite large change in
the Roscolar far outweighed the Roscolene and Gelatran
changes. The Roscolene Special Lavender was the most
stable needing forty-five hours to decrease 4% in transmission in the blue area (see Figure 3.12). The Gelatran
change fell within the standard of acceptance (Figure
3.32). But the 35% increase in transmission in the red area
of the Roscolar by thirty hours, and a change of 37% at
the center of the color sheet by forty-five hours as compared with zero exposure show a very unstable color
medium (Figure 3.22). The fact that the Roscolar had
visibly faded early in the test, and that it had increased
10% in transm ission by eighteen hours raises a serious
question as to the practicability of its use. The GaiserRootes maximum change average of ± 10.4% in the lavender color area of five gelatines and plastics shows that the
Gelatran Surprise Pink improves on the brands previously
tested, though the Roscolene Special Lavender remains
extremely stable as in the previous test.
The Roscolar and Gelatran bastard ambers showed a
very good color stability, the Roscolar decreasing only 3%
overall (see Figure 4.22), and the Gelatran increasing 5%
in the red area by eighteen hours but changing no more
than that (Figure 4.32). The more heavily absorptive
Roscolene Bastard Amber lost much of its absorptive
quality in the yellow-green area, becoming nearly the
spectral equ ivalent of the other two brands by th irty
hours (Figure4.12). The stability of the two new products
is probably due to the high overall transmission of these
colors in areas which allow for a high spectral efficiency.
Despite some changes in transmission, the Roscolene
and Roscolar pale blues showed a lack of significant
changes pointing to the fact that they fall within the
acceptability range. Roscolene Pale Blue decreased 3% in
the blue-green area by twenty-one hours and increased 8%
in the red area by five hours but no more (see Figure
5.12). The maximum change in the Roscolar Pale Blue
was a decrease of 7% in the blue-green area by twenty-four
hours (Figure 5.22). Here, as in the case of the Roscolar
and Gelatran bastard ambers, the high overall transmission
of pale blue probably accounted for the absence of
significant change.
he series of comparisons of the center vs. the one-andone-half inch off center samples at forty-five hours for all
colors reveals a significant fact (see the series of Figures
with the last digit as 3). Only in two of the fourteen cases
were there no changes. In all other cases the center
samples more closely agree with the maximum change
from zero than did the peripheral samples. Gaiser and

Rootes had found that there was no significant difference
between the center and peripheral samples. However, they
had used either ellipsoidal reflector spotlights or spherical
reflector spotlights at flood focus, both of which are
circumstances which would spread the light more evenly
over the entire piece of color medium. This study,
in contrast, used spherical reflector spotl ights at spot
focus. This focus concentrates the most light and heat
at the center of the color medium, but gives less light
and heat at the peripheral circumference used in th is
study. An acutal measurement of the footcandles of
light available in the beam of the instruments used in
this test showed that the footcandle readings gradually
decreased as the meter was moved from the center to the
edges of the beam. Further testing needs to be done in
this area, probably using many more instruments and
pieces of color medium so that samples can be taken from
the axis for all exposure times. It is felt that this would
add validity to the results of the current study.
Conclusions
No sweeping conclusions can be made on the basis of
the results of this study. Further research is needed in
many areas to confirm or revise the results, Still, some
observations and tentative conclusions can be made.
1. The effects of tu ngsten light, wh ich has higher transmission in the amber and red areas (see Figure Bl, may
well be responsible for the fact that color media with
high transmission in the blue areas tend to decrease in
transmission when exposed to tungsten light for a long
period of time, while those with low transmission in the
yellow-green or red areas tend to increase in those areas
after exposure.
2. Where deterioration of color medium stabi lity
occurs, the maximum most often occurs between fifteen
and thirty hours with twenty-four hours as an average.
This corroborates the same conclusions of Gaiser and
Rootes. This study, which ran forty-five hours as opposed
to the twenty-seven hours used by Gaiser and Rootes,
found that a reversal of deterioration occurs after the
max imum deterioration. The farthest point in th is reversal
occurs between thirty-three and forty-five hours with
forty-two hours as the average.
3. The results of this test, which shows that variations
over the time of exposure follow no particular pattern,
seems to invalidate the overly precise selection of colors
practiced by some Iighting designers. The variable deterioration and subsequent restoration of color transmission evident here occurred while lighting variables were
stabilized. It might be suggested, then, that the complex
combination of these variables (which would be the case
under stage use) would seem to negate any meticulous
attempt to present the same color picture to the audience
for each performance.
4. The two new products, while representing improve-

THEATRE DESIGN AND TECHNOLOGY

OCTOBER. 1973

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