Theatre Design & Technology - Oct 1973 - 21

and Roscolar are nearly equal when new, with only
slight differences noticeable on the graph. The Gelatran,
which differs visually from the others in that it is less
orange and more yellow, shows this difference spectrally
in that it consistently transmits 30% higher in the green
area.

shows a constant decrease in transmission in the blue area,
from a transmittance of 55% at zero hours to 38% at 24
hours (see also Figure 1.11), but then from this low
point transmission gradually increases to almost 50% by
39 hours. Figure 1.13 shows, however, that the effect of
light at the center of the beam at 45 hours is closest to
38% (the low point for peripheral measurement at 24
hours), while the sample taken one-and-one-half inches
off center reaches 50% again at 45 hours. Still, there is a
change of over 17% by 27 hours, and a 10% change is
reached between 15 and 18 hours.

The Roscolene Golden Amber shows itself to be a very
stable color throughout its entire exposure time (Figures
2.11, 2.12). The loss of 5% transmission in the red area
which occurs in two jumps between zero and 27 hours reverses itself in two changes again and by 45 hours reads
almost exactly the same as at zero hours. No graph of the
center and off-center 45-hour samples is offered as there
was no apparent change.

The Roscolar Primary Blue seems to follow somewhat
the same pattern, although the widest change just approaches 10% (see Figures 1.21, 1.22, and 1.23). A
decrease of 8-10% gradually occurs in the blue area until
18 hours then an increase in percentage occurs at 42
hours (Fig. 1.22). The 45 hour center sample (Fig. 1.23)
corresponds with the eighteen hour peripheral sample,
while the 45 hour off-center sample reads about 4%
higher.

The Roscolar Golden Amber shows some instability
in the orange and red areas of the spectrum, losing 12% in
those areas by 5 hours, increasing in transmission in those
areas to within 3% of the original transmission by 10
hours, but losing 12% again by 27 hours (Figures 2.21,
2.22). As time exposure increases the loss of transmission
again reverses itself, so that by 42 hours the original transmission in the orange-red area is regained. Also, between
18 and 30 hours this color begins to transmit up to 7% in
the violet and blue areas; before 18 and after 30 hours
there is no transmission in these areas. At 45 hours the
center and off-center samples agree, except for a difference of approximately 5% in the orange-red area (Figure
2.23). A careful recheck of original media and samples

The Gelatran Primary Blue also follows this pattern
(Figures 1.31-1.33) but shows even less change, 8% overall. The largest variation comes again at 18 hours before a
gradual increase brings the last readings to within 3% of
the zero hour exposure. Here also is a 3-4% variation in
the center and off-center 45-hour readings.
Figure 2.00 shows the three medium/golden amber
spectral transmittance curves before exposure. Roscolene

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THEATRE DESIGN AND TECHNOLOGY

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21
Table of Contents for the Digital Edition of Theatre Design & Technology - Oct 1973
