Theatre Design & Technology - Summer 1983 - 27

TECHNICAL REPORT

Editor: F. M. Wolff

Cab-O-Sil in Scene Paint
by Bruce A. Koenig

Cab-O-Sit is a fluffy, white, extremeTo begin the experiment it was
started decreasing and there was a slight
ly fine powder that is 99010 silicon diox- necessary to determine how much Cab- tendency for the colors to gray. This
ide. It is manufactured by the Cabot O-Sil could be added to our standard chroma shift was most noticeable with
Corporation in Boston, Massachusetts size water mixture (one part glue to
Primrose Yellow, Ultramarine Blue and
and costs approximately $45.00 for a 10 seven parts water) before some problem
Hercules Black, the latter two posing the
lb. (4.5 kg.) bag of Grade M-5. The might occur. For this test a measured greatest problem as they began to lose
submicroscopic particles which form quantity of Cab-O-Sil was placed in an
their "depth." After several test batches,
Cab-O-Sil sinter together to create empty bucket, followed by 20 Imperial
the best size water mixture contained Vz
chain-like formations, making it an ex- ounces (19.2 U.S. fluid ounces) of poly- cup of Cab-O-Sil (worth approximately
cellent filler and thickening agent. It is vinyl glue (Swifts #3995). The mixture 8lr ) for every 24 Imperial ounces (23.1
an extremely light substance, weighing was stirred into a paste and 140 Imperial U.S. fluid ounces) of size water.
only 2.3 pounds per cubic foot for the ounces (134.5 U.S. fluid ounces) of
Having determined the proper
M-5 grade, and chemically so pure that water were added. The resultant mix- amount of Cab-O-Sil to use in the size
it is also used as a food additive. Be- ture became the size water for mixing water mixture, we set out to check the
cause of these properties it is included in several batches of di fferent colored pig- coverage and hiding ability of paints
such products as toothpastes, lubricants, ments, as well as different weight per with Cab-O-Sil added. To three Imperihair shampoos, adhesives, weather seal- volume pigments. Gradually more and al quarts (115.5 U.S. fluid ounces) of
ants, plastics, and paints. Readers who more Cab-O-Sil was introduced into size water containing 2 Vz cups of Cabare familiar with Cab-O-Sil probably re- each new batch of size water until two O-Sil, enough pigment was added to
ceived their initiation to this unique problems arose. When too much Cab- produce the same viscosity with each
substance by using it as a thickening and O-Sil was used the coverage efficiency color. The amount of pigment varied
thixotropic agent with fiberglass resin,
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thereby creating a fiberglass paste which
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allowed more control of the resin for
-25: =2
-es t =3
Tes t =1
Pi a-en t ReQu red
(o'.erdoe
Hieing Cnaracterlstics
certain prop construction.
(for 3 Irperial) (in :-oerial ounces)
(Odt =1
Quarts
ot only does Cab-O-Sil increase the
Without
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'.llthout
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32
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ments for scene painting, with polyvinyl
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a 0
25
glue as a binder, I decided to experiment
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20
2 2
2 2
with Cab-O-Sil as an additive to combat
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the continual problems with this paint'S
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rapid settling and its inability [0 "hide"
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certain colors when repainting scenery.
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26

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Table of Contents for the Digital Edition of Theatre Design & Technology - Summer 1983
