Chemical Tour

HEALTH & SAFETY
Chemical Tour
A Guided Tour Through the Labyrinth ofChemicals used in Theatre Crafts
By Thurston James
HE rhearre crafrsperson has always been eager ro
accepr new rechnology imo his or her shop as
soon as ir develops. Mosr of rhe chemicals we
use in rhe rhearre were nor formulared for our
benefir, rhey were designed for indusrrial purposes, bur we have been quick ro open our arms
and give rhem a warm welcome. Alrhough we
have discovered problems wirh some of rhe marerials, we have
nor rescinded rhe welcome.
Some of mese chemicals are perfecdy safe ro use. Mosr are safe
when used wim precaurions. A few are dangerously poisonous.
This arride will arrempr ro arrange me chemicals according ro meir
use, place rheir names imo an undersrandable caralog, poim our
some of me dangers, and sreer you away from me mosr roxic.
Names: If you have no background in chemisrry, you may
find rhe grear number of mulri-syllable chemical names overwhelming. I did. I confess rhar as rhe lisr of chemicals I was
using in rhe consrrucrion of propereies grew, I was imimidared.
The lisr seemed unending-an insurmoumable moumain.
Unconsciously, I rebelled, recognizing only rhe few rerms I
found ro be absolurely necessary. I became comforrable working
wirh molding and casring mare rials long before I decided ro sore
our rheir various chemical names. Now, I can happily assure you
rhar alrhough rhe lisr is long, ir is finire and rhar ir can be simplified and conquered by grouping rhe individual enrries according ro rheir similariries.
Uses: Indusrry is srill me bulk consumer of mosr chemicals.
Typically, manufacrurers like ro sell meir produce in 50 gallon barrels and resisr packaging mem in gallon sizes for rhe hobbyisr and
rhe rhearre rechnician. Srill, mere are some companies who carer ro
our needs by packaging me chemicals in smaller unirs, bur rhere is
a price increase for rhe service.
Toxic Risks: Cerrain chemicals have been recognized as dangerous if used wimour safeguards. The manufacrurer, aceing
responsibly, arremprs ro change me compound when he can,
designing me hazardous oue. Some manufacrurers have gone so far
as ro drop cereain producrs from rheir line considering mem roo
risky ro sell. Remarkably, mere are several solvents which have been
in common use for many years and can srill be purchased in me
hardware srore, even rhough rhey are dangerously poisonous.
These produces are so useful, rhey remain on me marker wirh
safery warnings and explicare direcrions on how rhe produce
should be used.
Ie is imporrant ro realize rhar you, rhe consumer, have a
responsibiliry, roo. No one has more reason ro be interesred in your
healm man you yourself. You musr become aware of heaIrh hazards, and decide wherher you want ro run rhe risk of using parric-
ular producrs. In many cases you can choose a less roxic marerial.
Be aware rhar for almosr all producrs "Marerial Safery Dara
Sheers" (MSDS) are available from me disrriburor or manufacrurer
of each produce. Ir is definirely worrh me rime and rrouble ro
acquire me MSDS for produces you are using-or contemplaring
use. The MSDS will provide derailed informarion on me risks of
using each producr along wirh appropriare derails on how ro deal
wim srorage, spills, fire, and firsr aid.
FOAMS
Several plasrics can be expanded ro form a produce available as
eimer ridged or flexible foam. In my early years, I lumped all solid
marerials imo a single bag and mentally labeled ir"sryrofoam"; if
me foam happened ro be flexible, I called ir "foam rubber!" This
was, of course, an erroneous simplificarion.
Foamed plasric in a rigid form is widely used in manufacruring
for hear insularion and florarion devices. Indusrry uses flexible foam
for insularion, air-righr sealing, and for rnamesses and cushions.
Only mree producrs are of major interesr ro me mearre
craftsperson:
Polystyrene foam-Dow Chemical owns me rrademark Styrofoam
bur several manufacrurers are producing expanded polysryrene.
This foam is available in cwo basic formularions, easily idemified by
meir color: whire and blue. Whire sryrene foam will burn and is
doubly dangerous in a fire-Ie nor only flames, bur in me process ir
produces a black smoke containing roxic sryrene gas. Blue foam is
flame resisrane.
Urethane foam-Urerhane is probably me mosr useful foamed
producr ro me mearre rechnician. Ie can be purchased in a variery
of sizes, in born flexible and rigid form. A rwo-parr liquid kir, ro be
expanded by me consumer, is also available.
One facror mar adds ro me confusion of undemanding plasrics is mar me same plasric may appear in many different forms.
Polyuremane is one such producr-ir is available as a foam, as an
unfoamed solid, and as a rubber compound. The rubber produce is
explained below in rhe secrion on mermoser plasrics.)
Rigid urethane foam-Rigid uremane foam is widely used in me
mearre for consrrucring lighrweighr srone work and cornice moldings, in sculpring figures, and making turned balusrrades.
Flexible urethane foam-This produce is used in rhe prop room
as ir is in indusrry for making cushions and doing cusrom upholsrery.
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The [\vo-parr urerhane kir-Liquid urerhane and a foaming agem
are mixed to make a rapidly expanding foam in a varieC)' of densiries. When rhe urerhane begins to foam, ir is poured to make freeform rocks and bread sruffs. Or ir is formed by pouring che
foaming liquid inro a mold to make very conrrolled casrings.
The [\vo-parr urerhane kir musr be used wirh srricr safeguards.
In rhe liquid srate these chemicals are dangerous to eyes and skin,
so you must protect yourself by wearing gloves and goggles. The
gas produced when you mix che componems is toxic, so you must
protect your lungs by wearing a respiraror and working in a fresh
air envlronmenr.
Polyethylene foam-This foam comes as a round rod in a wide
range of diameters from 1/2" ro 6." It is flexible and is used in
industry as an insularor and sealanr. The scene technician finds rhis
product very useful because of irs flexibiliry in making curved
moldings. He splirs the rod down rhe middle on a bandsaw and
uses it ro make 1/2 round moldings. Ir can be splir a second time
and be used ro make flexible 1/4 round moldings.
I willmenrion in passing rhar several other plastics-vinyl, epoxies,
silicones, cellulosics, and phenolics-ean be expanded ro make
foams, each having irs own properries. Bur let's not allow these ro
clurrer our minds. They may be of some inrerest ro the experimental rhearre crafrsman, bur most of us can consider these ro be JUSt a
litde roo exoric to borher wirh.
THERMOSET PLASTICS
Laminating resin-Very strong castings with a thin cross section
are made by saruraring fiberglass clorh wirh polyesrer laminaring
resin. The resulrant casring is remarkably srrong for irs weighr, so
much so thar auromobile bodies can be made of sheers of laminated fiberglass clorh. Boars, barhrub and shower sralls, and swimming pools are also made of laminared fiberglass. In rhe thearre we
make armor, breastplares, masks, or any arricle we wanr ro be rhin,
liglmveight, and exrremely durable. We also take advanrage of the
warerright properries of fiberglass by using ir ro line srage founrains
and wading pools.
Plastic body filler (Bondo)-Polyesrer resin is somerimes mixed
wirh fillers ro make a purC)'. One popular product carries rhe rradename Bondo--rhe name has become generic ro cover all plasric
body fillers. Ir bonds to meral and plasric surfaces and is produced
for rhe auro body repairmen ro fill small denrs in hoods, fenders,
doors, erc. The rhearre rechnician finds chis producr very useful as
a casring marerial, for making rextures, or like rhe auro repairman,
good for filling imperfecrions in meral and plasric.
Epoxy Resins-This is anorher family of resins having a similariC)'
ro polyesrer resin. The epoxy adhesives and purties are especially
useful ro thearre rechnicians.
Casting resin-This resin hardens ro a solid mass, accompanied
by hear, when mixed wirh a caralysr. lr is a lirrle less toxic rhan
polyesrer (nor much), a lirde srronger (nor much), and more
expensive. Epoxy casring resin can also be used wirh glass fibers ro
make a very srrong fiberglass casring.
Thermosers are a class of liquid resins which solidifY ro a permanenr shape when mixed with a caralysr. Of rhe several resins rhar
fall inro chis class, che rhearre crafrsman will nor likely need ro be
concerned wirh more rhan rhese-polyesrer resin, epoxy, and rhe
room remperarure vulcanizing (RTV) resins urerhane and silicone.
Epoxy glue-Epoxy resins srick ro almosr any surface making
rhem a wonderful fasr-serring adhesive. Mosr everybody is familiar
wirh "five-minure epoxy" which comes in [\vo rubes, an epo>.'}' resin
cemenr and a hardener.
Polyester Resins-When you hear rhe word "polyesrer" you may
be led ro rhink of a fabric, useful for making suirs. Ir mighr seem
unreasonable ro find any relationship be[\veen the "fabric" and
"casting resin." However, the chreads in che suit and the resins
packaged for molding and casting projects are indeed based in the
same chemistry. There is a whole family of polyester resins, each
compounded ro fill a slighdy differenr purpose.
Epoxy putty-A purC)' carrying rhe rradename JB Weld unires
renaciously wirh merals and is used ro bond such surfaces rogecher.
Anorher purry called Gapoxio has rhe consisrency of modeling clay
is hand workable. Plumbers use rhe purC)' ro repair minor warer
pipe leaks, even in rhe presence of warer. This purC)' can also be
used like clay ro make small sculprures rhar ser up ro be permanendy hard wirhin an hour.
Casting resin-Polyester casting resin, as its name suggests, is used
in casting figurines, and other chree dimensional objects in a mold.
The resin is mixed with a catalyst-MEK peroxide-ro harden ir.
The curing is usually accompanied with some detectable heat,
especially if the casting is large. Small castings require more catalysr
and a longer curing period. Casting resin is usually clear, bur it can
be colored by adding dyes. You can reinforce the casting by adding
glass fibers ro the resin; however che job of making a strong fiberglass lamination is lefr ro a slighdy differenr formulation called
laminating resin.
RTV Rubbers-There are [\vo rhermoser rubbers of significanr
inreresr to rhearre crafrs and are used in molding and casring. They
carry rhe lerrers RTV (room remperarure vulcanizing) which
means rhar rhey vulcanize ar room remperarure withour exrernal
hear.
Fiberglass-Fiberglass is jusr rhar. It is glass spun in a fiber so fine
thar ir has lost irs mosr familiar characrerisric-ir doesn'r break, ir
bends. The fiber is woven inro clorh of several weighrs. It is pressed
inro a mar, or ir is jusr packaged in loose chopped lengths. The
clorh, mar, and rhe chopped fibers are used ro reinforce resinsmosr commonly polyesrer resin. The rerm "fiberglass" can refer ro
eirher rhe raw glass fibers or rhe finished laminarion afrer rhe glass
has been combined wirh resin.
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SPRING
1995
TD&T
Silicone RTV-The besr molds are made from silicone RTV casring rubber. This rubber has reproducrive qualiries berrer than
could ever be required for rhearre applicarions. Ir is rough, durable,
resisranr ro high remperarures, and reasonably safe [Q use. The
major drawback is rhe cosr. Ir is a rarher expensive producr.
Urethane RTV-Reasonably good molds are made from urerhane
RTV rubber. The big amacrion of rhis producr is irs price. The
reproducrive rrairs are cerrainly good enough for srage purposes,
bur, as ir is more roxic rhan silicone, a respiraror musr be used.
Thermoser plasrics musr all be used wirh prudenr safeguards. All
caralysrs used to cure rhe various resins are corrosive, arracking skin
rissue wirh a vengeance; your eyes are parricularly sensirive ro damage. Gloves and goggles musr be worn. Polyesrer producrs are rhe
mosr dangerous of the thermoser plasrics. Polyesrer resin is suspeered of being a carcinogen, and in California rhe packaging conrainers musr carry a warning label. Even if rhis producr is
evenrually proven ro be cancer-free, we know rhar rhe fumes of the
resin are harmful ro rhe linings of rhe lungs. A respiraror venrilarion are required.
dienr in larex rubbers. This is one producr rhar has been developed wirh rhe rheatre in mind. The marerial is appreciared by
prop builders as rhey work on molding and casring projecrs and
by rhe make-up artist. Larex rubber differs from rhe RTV rubbers menrioned earlier in rhar rhe liquid cures ro a flexible solid
mass wirhour rhe inrroduerion of a caralyst. Curing rakes place
as a soh'enr is removed from rhe compound rhrough absorprion
andlor evaporarion.
THERMOPLASTICS
Casting Latex and Neoprene-These rubbers are used ro make
flexible casrings by pouring the liquid rubber inro a plasrer mold.
The plasrer absorbs soh'enr from the mixrure and rhe casring is
cured as a resulr of rhis blorring and air drying.
Thermoplasrics are a broad class of plasric marerials thar are sold ar
room remperarure bur will sofren when rhey are heared. The plasric can be shaped while ir is sofr and ir holds rhe new shape when
ir is cooled. The process can be repeared again and again, a grear
number of rimes, before rhe marerial finally breaks down.
Sheet Thermoplastics-Several plasrics, available in sheer form, can
be shaped in a vacuum forming process. Clamped in an open frame,
the sheer is heared ro irs sofrening point. The soft sheer is then placed
over a solid objecr and a vacuum is applied ro remove any air exisring berween the sheer and the object. This forces the plasric ro hug
close ro the parrern. \'\fhen the sheer cools, ir rerains irs new shape.
Styrene-The mosr common plasric ro be used in rhe vacuum
forming process is high impacr whire styrene. Ir is available in
many thicknesses from 10 ro 80 mil. The mosr useful thickness for
prop and scenic use is 30 ro 40 mil.
Acrylic (Plexiglas)-Sheer acrylic is clear, and since ir will nor
sharrer in a dangerous way, ir is used ro make window panes for
thearrical serrings. Thin sheers of rhis plasric can be casr in the vacuum-forming process ro make clear objecrs.
Mylar-Aluminized mylar is highly reflecrive and can be used ro
make mirrors. One producr is called "hear shrink" plasric. The
sheer is srrerched and srapled ro a wooden frame. As. hear is applied
ro rhe sheer ir shrinks enough ro remove all remaining wrinkles,
and rhe resulting sheer is an inexpensive flaw free mirror.
Solid Thermoplastics-There are several rhermoplasric casring
marerials, in rhe form of pellers or a molded sheet. lr is likely you
can go enrirely rhrough your thearrical career wirhour being called
on ro know rhe chemical names, they are simply known by rheir
tradenames Friendly Plastic, Hexcelite, Protoplast, Vam-form, and
others. You needn'r bother with chemical names for rhese plasrics
unless you have a srrong inreresr-bur if you do have rhe inreresr,
know rhar they are mostly from rhe polyolefin family including
polyerhylene and polypropylene. Friendly Plastic is a polyesrer peller, formulared ro work as a hor melt.
Hor glue (erhyl vinyl acerare) is another solid thermoplasric,
bur you will ger along jusr fine calling ir hor glue.
There is nor a lor ro say abour rhe safe handling of rhese marerials. Some fumes wirh a dereerable odor are produced when the
plasric is heared, bur rhey are more irriraring rhan poisonous. The
only real danger wirh is encounrered when you overhear a rhermoplasric and ir begins ro burn. A black smoke is produced which is
roxic and dangerous.
Filled Latex-When rhe larex is mixed wirh clay fillers, rhe casrings have more body. The walls of rhe casring are thicker and the
objecr looses a considerable amounr of irs flexibility.
Foam Latex-A kir consisring of four separare chemicals is on rhe
marker used for making masks and orher rhin wall casrings. Ir is
usually poured inro a mold thar has internal and exrernal walls and
rhe foaming larex mLxrure is formed berween rhe rwo walls. This
process does require exrernal hear ro cure the casring.
Balloon Latex-This is a compound thar is a1mosr pure larex. Ir is
painred or sprayed in exrremely thin coarings for maximum srrerch.
Cosmetic Quality Latex-This larex is applied directly ro an
acrors face ro make scars, warrs, and orher blemishes as well as
entire prostheric appliances (noses, ears, erc.)
POLY VINYL ACETATE (PYA)
You may, in this world of roxic chemicals, wonder, ''Are there no
chemical producrs I can use wirh safety?" Yes, bless your hearr,
rhere are! The following adhesives and rexrured coarings are in a
class of rheir own-and are wonderfully benign.
White Glue-PVA has been formulared inro several whire glue
producrs, some warer soluble and some thar are highly warer resisrant. One well known tradename is Eimers.
Flex-Glue-An adhesive long used in binding books has recently
found a place in the heans of prop builders and costumers because
ir remains flexible afrer ir dries. Ir never hardens. One produer thar
is packaged specifically for rhe thearre crafrsman goes by rhe rradename Phlex-glll and is used for far more rhan jusr an adhesive. Ir is
employed as a painr binder, a rexrurIng agenr, an embedding
medium, and a coaring marerial.
PYA Texture Coating-PYA is so good ar making rexrured surfaces thar rhick formularions are being devised specifically for theatre crafrsmen and arrisrs. One such producr rhar has gorren
popular in rhe lasr rwo or rhree years is SCIIlpt-or-Coat. Ir began as
a coaring ro drape and sriffen fabrics. Ir was found ro give foam
sculptures a smooth surface, and rhen rhe produer grew in rhe
hands of enrhusiasric users ro be very versarile.
SOLVENTS
LATEX RUBBER
The milky whire juice of certain rubber rrees is rhe main ingre-
The lasr caregory is solvenrs. Solvenrs are among rhe mosr roxic
chemicals in common lise. These can be all rhe more insidious,
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S P R I N G
55
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materials and erroneously consider them to be old friends. The following list is roughly arranged in the order of relative toxicity.
It is well to note that almost all solvents can dissolve the natural oils from your skin and in almost all cases you should protect
your hands with rubber gloves.
Water-This most common solvent is often overlooked because it
is so vety common. Water and detergent should be used in many
decreasing operations where alcohol, paint thinner, or acetone are
typically used.
Alcohol-Alcohol is used as a fuel, a thinner for shellac, and as a
solvent for several dyes, It should be used in a large open space to
prevent a build-up of fumes in the atmosphere.
Paint Thinner-Sometimes known as "spirits," this is a thinning
agent for oil based enamel paints, and a solvem frequently used for
cleaning greasy objects. It should be used in an open space or an
ventilated area.
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Ammonia-This household cleaning agent is also used as a stabilizet and solvent in latex casting rubbers. A respiratory irritant, it
must be used in a well-ventilated area even if used in small quantities. In larger concentrations, you must use a respirator.
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Lacquer Thinner-It is a thinning agent for lacquer and other oil
based paints. Lacquer thinner is highly inflammable. The fumes
from this thinner are an irritant of the respiratory tract and the
central nervous system and the product should be used with forced
ventilation and a respirator.
Acetone-Acetone is a thinner for contact cement, reSinS, and
plastics. It is dangerously inflammable. Although acetone is
extremely volatile and requires forced ventilation and a respirator.
it is the least hazardous of the ketone class.
TO SHARE OR
NOT TO SHARE...
Gasoline-A fuel and degreasing agem, it should never be used
except as a fuel for automobiles because it is highly inflammable
and may even explode.
MEK (methyl ethyl ketone}-An extremely dangerous solvem. It
is a very volatile liquid that quickly fills the air with tOxic fumes
that can cause permanent damage to the central nervous system.
Use acetOne with proper precautions as a substitute for MEK.
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56
SPRING
1995
TD&T
Carbon Tetrachloride-This chemical was in common use in the
past a dry cleaner. Spot remover, and fire extinguisher. The fumes
are poisonous and capable of causing liver cancer. Do not use.
Benzene (benzol)-This solvent is a carcinogen causing leukemia.
It is rarely used in its natural state. bur can be found in some cutting oils, gasolines, and dyes, Be on the lookout for benzene and do
not use......
THURSTON JAMES was the properties master at UCLA Theater
Department until his retirement in 1991. He is the author offour
books on the techniques of building props and is wrrentLy teaching
properties construction and mask making at California Jnsitute ofthe
Arts.