Health Hazards : Plaster

 TRADITIONAL SCULPTURE HAZARDS

By Michael McCann, Ph.D., C.I.H., and Angela Babin, M.S.





INTRODUCTION



  Many artists work with traditional sculptural materials

including plaster, stone, lapidary, clay, wax, and modeling

materials.  This data sheet will provide hazards and safety

information for certain traditional processes.  Our data

sheets "Ceramics", "Metal Working and Jewelry Hazards",

"Plastics" and "Woodworking." have information about

other sculptural materials.





PLASTER



  Plaster can be carved, modeled, and casted.  Varieties of

plaster include: Plaster of Paris, casting plaster, white art

plaster, molding plaster, and Hydrocal.  These are all

varieties of calcined gypsum, composed of calcium sulfate.

  Plaster is mixed by sifting the powder into water.

Sometimes salt, potassium sulfate, or potassium alum is

added to speed setting, or borax, diluted acetic acid, or

burnt lime is added to retard setting of the plaster.  Silica

sand, vermiculite, sand, and coarse stone can be added to

the plaster for textural effects.  Wet or dry plaster is

carved and modeled with special plaster carving chisels,

knives, rasps, and scrapers and other tools.



Hazards

1. Plaster dust (calcium sulfate) is slightly irritating to the

eyes and respiratory system.  In situations where there is

heavy inhalation of the dust, more severe respiratory

problems can result.

2. Potassium sulfate and potassium alum are slightly toxic

by ingestion; potassium alum is slightly toxic by skin

contact, and can cause mild irritation or allergies in some

people.

3. Borax is moderately toxic by ingestion, by inhalation,

and by absorption through burns or other skin injuries.  It

is also slightly toxic by skin contact, causing alkali burns.

4. Concentrated acetic acid is highly corrosive by

ingestion, inhalation, and skin contact.

5. Burnt lime (calcium oxide) is moderately corrosive by

skin contact (especially if the skin is wet), and highly toxic

by inhalation or ingestion.

6. Many of the additives used may be hazardous.  Silica

and vermiculite dust are highly toxic by inhalation, and

may cause silicosis.  Small amounts are not a major

hazard.

7. Careless use and storage of sharp tools can cause

accidents.  Chipping set plaster can result in eye injuries

from flying chips.



Precautions

1. For mixing large amounts of plaster at one time, wear

a NIOSH-approved dust mask.  Vacuum or mop up plaster

dust carefully; do not sweep.

2. Wear gloves and goggles when mixing acetic acid and

burnt lime.  For large amounts of burnt lime, wear an

approved toxic dust mask.

3. When adding hazardous materials to plaster, wear an

approved toxic dust mask and clean up dust carefully by

wet mopping or vacuuming.

4. Always carve or cut in a direction away from you, and

keep hands behind the tool.  If the tool falls, don't try to

catch it.

5. Wear ANSI-approved safety goggles when chipping

plaster.

6. Store plaster in sealed containers or plastic sealed bags

rather than paper bags which can rip open.





PLASTER MOLDS

  Mold releases used with plaster include vaseline, tincture

of green soap, auto paste wax-benzine, silicone-grease-

benzine, and mineral oil-petroleum jelly.  In waste

molding, the plaster mold is chipped away.



Hazards

1. Benzine used with many mold releases is moderately

toxic by skin contact and inhalation, and is highly toxic by

ingestion.  It is also flammable.

2. Making plaster casts of hands, legs, and other body

parts can be very hazardous due to the heat released during

the setting process.  Many children and adults have been

severely burned doing this.



Precautions

1. Wear gloves and goggles when pouring benzine.  Store

in safety containers and do not use near open flames or

cigarettes.

2. Do not use plaster for body part casts.  Instead, use a

plaster-impregnated bandage (such as Johnson and

Johnson's Pariscraft), along with vaseline or similar mold

release as protection.





PLASTER FINISHING

    Plaster can be finished in many ways.  It can be

painted with paint or powdered pigments, or dyes can be

added directly to the plaster mix.  Patinas are made by

sealing the plaster with shellac or acrylic sprays.  They can

also be made with a 50/50 mixture of water and white

glue, with water-based glue mixed with a 50/50 mixture of

lacquer and alcohol, or with bronzing liquids.





Hazards

1. Powdered pigments and dyes are often hazardous by

inhalation or ingestion, and in some cases by skin contact.

See our data sheet "Art Painting and Drawing" and

"Dyeing Safely" for more information on the pigments used

to finish plaster.

2. Lacquers contain solvents that are highly toxic by

inhalation and moderately toxic by skin contact.  Alcohol

and shellac are slightly toxic unless the shellac contains

moderately toxic methyl alcohol.  These solvents are also

flammable.



Precautions

1. Wear a NIOSH-approved dust mask when using

powdered pigments or dyes.  Brush or dip dyes or paints

rather than spraying.

2. When using solvents, have good general ventilation and

wear gloves and goggles.  Store solvents safely, and keep

them away from open flames and lit cigarettes; dispose of

solvent-soaked rags in approved waste disposal cans which

are emptied each day.





STONES AND LAPIDARY



  Stone carving involves chipping, scraping, fracturing,

flaking, crushing, and pulverizing with a wide variety of

tools.  Soft stones can be worked with manual tools

whereas hard stones require crushing and pulverizing with

electric and pneumatic tools.  Crushed stone can also be

used in casting procedures.





SOFT STONES

  Soft stones include soapstone (steatite), serpentine,

sandstone, African wonderstone, greenstone, sandstone,

limestone, alabaster, and several others.





HARD STONES

  Hard stones include granite and marble.  Electric tools

include saws, drills, grinders, and sanders, and pneumatic

tools include rotohammers, drills, and other tools powered

by compressed air.





CASTING STONES

  Stone casts can be made using Portland cement, sand,

and crushed stone.  Marble dust is often used with this

technique.  Cast concrete sculptures can also be made

using sand and Portland cement.   The commonest mold is

plaster with stearic acid/benzine as the mold release.

Portland cement contains calcium, aluminum, iron and

magnesium oxides, and about 5% free silica.  Some

modern cements have acrylic resins in them to give

stronger bonding.  Sometimes, fiberglass is added as a

reinforcement.



Hazards

1. Sandstone, soapstone, and granite are highly toxic by

inhalation because they contain large amounts of free silica.

Limestone, containing small amounts of free silica, is less

hazardous.  See Table 1.

2. Serpentine, soapstone, and greenstone may contain

asbestos, which can cause asbestosis, lung cancer,

mesothelioma, and stomach and intestinal cancers.

3. During chipping and other carving, flying chips and

pieces of rock may cause eye injury.  Grinding and

sanding can release small pieces of stone and dust which

are hazardous to the eyes.

4. Lifting heavy pieces of stone may cause back injuries.

5. Power tools create larger amounts of fine dust than hand

tools.  Pneumatic tools can create large amounts of fine

silica dust.

6. Pneumatic and electric tools and compressors can create

a noise hazard.  Temporary hearing loss can become

permanent with chronic exposure and noise can also

adversely affect the heart, circulation, blood pressure,

intestines, and balance.

7. Vibration from pneumatic equipment can cause

Raynaud's phenomenon, ("white fingers" or "dead fingers")

a circulation disease.  The hazard is greater with exposure

to cold, (e.g. the air blast from pneumatic tools).  This

temporary condition can spread to the whole hand and

cause permanent damage.

8. Electrical tools create the potential hazard of electrical

shock from improperly grounded or faulty wiring.

9. Calcium oxide in Portland cement is highly corrosive to

the eyes and respiratory tract, and is moderately corrosive

to the skin.  Allergic dermatitis can also occur due to

chromium contaminants in the cement.  The silica in the

cement is also highly toxic by inhalation.  Lung problems

from inhalation of Portland cement include emphysema,

bronchitis, and fibrosis.

10. Acrylic resins are skin irritants and sensitizers.  See

our data sheet on plastics for more information.



Precautions

1. Do not use stones which may contain asbestos unless

you are certain that your particular pieces are asbestos

free.  New York soapstones may contain asbestos, whereas

Vermont soapstones are usually asbestos free.  Alabaster is

a substitute.

2. Wear an NIOSH-approved toxic dust respirator when

carving all stones.  Particular care should be taken with

stones that contain free silica.

3.  Techniques to keep down dust levels in the air include

daily vacuuming or wet mopping, and use of a water spray

over your sculpture when you are carving.  Do not dry

sweep.

4. Wear chipping goggles to protect against flying

particles; wear protective shoes to protect against falling

stones.  Wear approved safety goggles when grinding,

sanding, or polishing.  For heavy grinding also wear a

face shield.

5. Change clothes and shower after work so as not to track

the dust home. Wash your clothes regularly.

6. When using carving tools, keep your hands behind the

tools, and carve or cut in a direction away from you.

Don't try to catch falling tools.

7. Use proper lifting techniques (bent knees).

8. Pneumatic and electric carving tools should be equipped

with portable exhaust systems.

9. All electric tools should be properly grounded and in

good repair.  Install ground fault circuit interrupters if

machines are within 6 feet of water that can splash.

10. Isolate the compressor far away and shield with sound-

absorbing materials.  Wear ear protection if necessary.

11. Protect against vibration damage from pneumatic tools

by measures such as having comfortable hand grips,

directing the air blast away from your hands, keeping

hands warm, taking frequent work breaks, and using

preventive medical measures such as massage and

exercises.

12. Tie long hair back, and don't wear ties, jewelry, or

loose clothing which can get caught by machinery.

13. Equip all grinding wheels, sanding machines, and

polishing wheels with local exhaust ventilation, and use wet

sanding and polishing techniques whenever possible to keep

down dust levels.





LAPIDARY

  Lapidary involves cutting and carving semiprecious stones

and has similar risks as hard stone carving.  Stones carved

include garnet, jasper, jade, agate, travertine, opal,

turquoise and many others.



Hazards

1. See stone hazards above.

2. The dust from quartz gemstones such as agate,

amethyst, onyx, and jasper is highly toxic because they are

made of silica.  Other gemstones such as turquoise and

garnet may be contaminated with substantial amounts of

free silica.  Opal is made of amorphous silica, which is

slightly toxic by inhalation.

3. Gem cutting machines can create very high noise levels.



Precautions

1. See stone precautions above.

2. In the absence of adequate local exhaust ventilation,

wear NIOSH-approved toxic dust respirator for sanding,

grinding, or polishing operations that create dust.  Use wet

grinding processes.



FINISHING STONE

  Stones can be finished by grinding, sanding, and

polishing, by either hand or with machines.  Polishing can

use a variety of materials, depending on the hardness of

the stone being polished.  Polishing materials include

carborundum (silicon carbide), corundum (alumina),

diamond dust, pumice, putty powder (tin oxide), rouge

(iron oxide), tripoli (silica), and cerium oxide.



Hazards

1. Grinding and sanding, especially with machines can

create fine dust from the stone which is being worked.

There are also inhalation hazards from grinding wheel dust

(especially sandstone wheels).  Some polishing materials

such as tripoli are highly toxic if inhaled in powder form.



Precautions

1. In the absence of adequate local exhaust ventilation,

wear NIOSH-approved toxic dust respirator for sanding,

grinding, or polishing operations that create dust.





Table 1.



NOT SIGNIFICANT OR SLIGHT HAZARDS,

VERY SMALL AMOUNTS FREE SILICA

alabaster, amber, bone ash, calcite, carborundum, diamond,

dolomite, gypsum, hematite, jade, marble, putty (tin),

travertine, whiting, wollastonite.



MAY CONTAIN LARGE AMOUNTS FREE SILICA

clays, feldspars, garnet, granite, greenstone, quartz (agate,

amethyst, chalcedony, chert, flint, lapis lazuli, lepidolite,

onyx, silica flour) opal, pumice, rouge (if silica-containing,

iron), sandstone, slate, silica-containing African

wonderstone, talc, tripoli, turquoise.



CONTAINING OTHER MODERATE TO EXTREMELY TOXIC INGREDIENTS

asbestos, carbon black (if contaminated with polycyclic

aromatic hydrocarbons), cerium oxide, cerrusite (lead),

coal, corundum (aluminum oxide), cryolite, erionite

(zeolite), fluorspar, lapis lazuli (ingestion may create

hydrogen sulfide), litharge (lead), malachite (copper),

serpentine (may contain asbestos), soapstone (talc), talc

(can have asbestos-type materials), vermiculite (asbestos),

witherite (barium), zirconia (allergen).











MODELING MATERIALS



CLAY

   Modeling materials used in sculpture include traditional

moist clays, non-hardening modeling clays, self-hardening

clays, oven-hardening clays, wax, and papier mache type

products.  See our data sheet "Ceramics" for more

information on clay.





MODELING COMPOUNDS

    Modeling clays of the plasticine type usually contain

China clay in an oil and petrolatum base.  Additives are

often present, including dyes, sulfur dioxide, vegetable oils,

aluminum silicate, preservatives, and turpentine.  These are

modeled and carved with simple tools.

  There are also a variety of polymer clays that are self-

hardening, or oven-hardening (e.g. FIMO, Sculpey), which

are not really clays at all.  These are often based on

polyvinyl chloride.  They are widely used in jewelry and

bead-making, and sometimes are inappropriately used with

children.



Hazards

1. Some of the additives in plasticine clays such as

turpentine and preservatives might cause skin irritation or

allergies, and sulfur dioxide might cause some respiratory

problems in certain asthmatics.  The amounts present are

usually small.

2. In the past, many of these materials contained di-

(ethylhexyl) phthalate (DEHP), a probable human

carcinogen, as a plasticizer.

3. The curing temperatures of different product are not the

same, and in some cases, very close to the temperatures at

which decomposition can occur.



Precautions

1. Use gloves or apply a barrier cream to hands if skin

irritation results from using plasticine modeling clays.

Wash hands with soap and water after contact.

2. Baking any art material in an oven which is also used

for food carries the risk of contaminating food.  Use a

separate oven, that has reliable temperature control and

only bake these products to their particular hardening

temperature.

3. Obtain the get the Material Safety Data Sheet (MSDS)

from the manufacturer or supplier, and make sure the

temperature of decomposition is not reached.

4. Do not use hardening modeling clays that have DEHP

as a plasticizer.  At this time, the longterm hazards of

replacement plasticizers have not been adequately

researched.

5. Use these products in front of a window exhaust fan.





WAX



  Many different types of waxes are used for modeling,

carving, and casting.  These include beeswax, ceresin,

carnauba, tallow, paraffin, and micro-crystalline wax.  In

addition there are the synthetic chlorinated waxes.  Solvents

used to dissolve various waxes include alcohol, acetone,

benzine, turpentine, ether, and carbon tetrachloride.

  Waxes are often softened for carving or modeling by

heating in a double boiler or with a light bulb, by

sculpting with tools warmed over an alcohol lamp, or by

the use of soldering irons, alcohol lamps, and blowpipes.

Wax can be melted for casting in a double boiler.

  Additives used with waxes include rosin, dyes, petroleum

jelly, mineral oil, and many solvents.



Hazards

1. Overheating wax can result in the release of flammable

wax vapors, as well as in the decomposition of the wax to

release acrolein fumes and other decomposition products

which are highly irritating by inhalation.  Explosions have

occurred from heating wax that contained water.

2. Alcohol and acetone are slightly toxic solvents by skin

contact and inhalation; benzine and turpentine are

moderately toxic by skin contact, inhalation, and ingestion.

Carbon tetrachloride is extremely toxic, possibly causing

liver cancer and severe liver damage, even from small

exposures.  Exposure to carbon tetrachloride can be fatal

by skin absorption or inhalation.

3. Chlorinated synthetic waxes are highly toxic by skin

contact and skin absorption, causing a severe form of acne

(chloracne).  Some may be contaminated with

polychlorinated biphenyls (PCBs), which are highly toxic,

causing chloracne, liver problems, and possibly cancer of

the pancreas and melanoma (a fatal form of skin cancer).



Precautions

1. Do not overheat waxes.  Use a double boiler and a

temperature-controlled hot plate, or a crock pot.  Do not

use an open flame to melt waxes.

2. Use the least hazardous solvent to dissolve your wax.

Do not use carbon tetrachloride under any circumstances.

Store solvents safely, do not smoke or have open flames

near solvents.  Dispose of solvent-soaked rags in an

approved waste disposal container which is emptied daily.

3. Do not use chlorinated synthetic waxes.



This data sheet is adapted from the second edition of Artist

Beware, by Michael McCann, Ph.D., C.I.H., 1992











FOR FURTHER INFORMATION





   Written and telephoned inquiries about hazards in the arts

will be answered by the Art Hazards Information Center of

the Center for Safety in the Arts.  Send a stamped, self-

addressed envelope for a list of our many publications.

Permission to reprint this data sheet may be requested in

writing from CSA.  Write: Center for Safety in the Arts,

5 Beekman Street, Suite 820, New York, NY 10038.

Telephone (212) 227-6220.

   CSA is partially supported with public funds from the

National Endowment for the Arts, the New York State

Council on the Arts, the New York City Department of

Cultural Affairs, and the NYS Department of Labor

Occupational Safety and Health Training and Education

Program.



(c) Center for Safety in the Arts, 1994.









--

Michael McCann

Internet: mmccann@rdz.stjohns.edu