SILK SCREEN PRINTING
By Ronald Fuchs and Michael McCann, Ph.D., C.I.H.
UIC Health in The Arts Library
Silk screen printing is one of the most hazardous processes in
the arts and crafts. Dermatitis, narcosis (dizziness, light-
headedness, fatigue, nausea, lack of coordination and headaches),
eye irritation, adverse reproductive hazards including increased
risk of miscarriage, and serious neurological problems can all
result from the processes of screen printing.
Traditionally, silk screen printing has been performed using organic solvent-
based materials. Water-based inks containing less hazardous
ingredients provide a safer and increasingly popular alternative.
SOLVENT-BASED SILK SCREEN PRINTING
The major hazard in silk screen printing comes from
exposure to the solvents in the inks, thinners, clean-up
materials, etc. Thinners such as lacquer thinner and are a
mixture of these and other hazardous solvents. The greatest
hazard is exposure through inhalation, causing narcosis
(dizziness, headache, nausea and light-headedness) from acute
exposures, and skin, liver, kidney, reproductive and nervous
system damage with repeated exposure. Skin absorption can also
produce these effects. It is also important to note that most of
these solvents are flammable.
An industrial hygiene study of a university silk screen
printing class verified that silk screen printing without
adequate ventilation can be extremely hazardous. This study
measured the breathing zone exposure of students and teaching
assistants during printing using poster inks, and cleaning using
toluene, xylene, mineral spirits, and lacquer thinners.
Without ventilation, measured air concentrations during
printing were 100 parts per million (ppm) of toluene for 100
minutes, 600 ppm of toluene and 92 ppm of xylene for 421 minutes,
and 410 ppm of toluene for 60 minutes. During cleaning, the
following measurements were made: 670 ppm of toluene for 28
minutes; 490 ppm of toluene and 250 ppm of methyl ethyl ketone
for 8 minutes; and 1900 ppm of toluene, 95 ppm of xylene and 180
ppm of methyl ethyl ketone for 34 minutes.
With local exhasut ventilation, the exposure levels were many
times lower with most measured concentrations below 1 ppm, and
all below 50 ppm. By way of comparison, the American Conference
of Governmental Industrial Hygienists (ACGIH) has set Threshold
Limit Values (TLVs) of 100 ppm averaged over an 8-hour day for
toluene and xylene, and 200 ppm for methyl ethyl ketone. The
ACGIH 15-minute TLVs are 150 ppm for toluene and xylene, and 300
ppm for methyl ethyl ketone. As you can see, the air sampling
carried out greatly exceeds these ACGIH recommended exposure
The hazards associated with screen preparation depend on the
materials used. For resist and blockout stencils we recommend
water-soluble glues, liquid wax and liquid frisket which contain
no toxic solvents nor require them for clean-up. They may cause
slight eye irritation if they splash in the eyes. Lacquers,
polyurethane varnishes, tusche, shellac and caustic resist
enamels are often used but contain large amounts of toxic
solvents. Turpentine, used to thin tusche, may cause skin or
respiratory allergies, and kidney damage.
For film stencils, water-soluble emulsion films are
recommended. The mixture of water and isopropyl alcohol adheres
the stencil to the screen, and while flammable, is only slightly
toxic. The adhering fluid for lacquer-type emulsions contains
acetates, ketones and alcohols, which are irritating to the skin
and are more toxic by inhalation.
The safest type of photostencils are diazo photoemulsions.
They are eye irritants by direct contact, but are otherwise not
very toxic. Ammonium dichromate, often used to sensitize
photoemulsions, can cause skin ulcers and allergies with direct
contact and inhalation of the powder can cause severe respirat-
ory irritation, ulceration of the nasal septum, and respiratory
allergies. Ammonium dichromate is also combustible. Silver
nitrate, another sensitizer, is corrosive to the skin and eyes.
Carbon arcs, sometimes used to expose photoemulsions, are highly
hazardous, giving off metal fumes, ozone and nitrogen dioxide,
which are strong lung irritants, and ultraviolet radiation which
harms the eye; carbon arcs are not recommended.
Printing and Drying
Many silk screen inks contain up to 50 percent hazardous
organic solvents. Poster inks can contain toluene and xylene,
which are highly toxic aromatic hydrocarbons, and large amounts
of mineral spirits. Other inks, e.g. vinyl inks, can contain
large amounts of other highly toxic solvents, for example,
isophorone. The bases, thinners, retarders, etc. used with
these inks also contain similarly hazardous solvents.
Direct exposure to the solvent vapors from the ink is a
serious problem during printing due to the close proximity of the
printer. Inhalation of the hazardous solvents during drying,
however, is the major source of exposure since large volumes of
solvent evaporate into the air in a short period of time.
Curing fabric inks by heating may release fumes which are
irritating to the respiratory system.
Clean-up is probably the most hazardous step in silk screen
printing because of the widespread use of highly toxic screen
washes and the practice of tossing solvent-soaked rags in open
wastepaper cans. This causes the evaporation of large amounts of
highly toxic vapors.
To reduce exposure to toxic vapors during
clean-up, substitute mineral spirits (or mineral spirits with 15%
added xylene for difficult jobs) for lacquer thinner, toluene,
xylene and other highly toxic solvents. These solvents are also
Proper safety is essential when working with all these toxic
substances. The elderly, people with chronic diseases, pregnant
women, and children are at especially high risk and should avoid
screen printing if possible. Consult your physician if you
suffer from heart trouble or a breathing ailment which can be
aggravated by toxic vapors. The following precautions will help
reduce the dangers in the processes of screen printing.
Solvents should be stored in approved, capped flammable
storage cabinets. Only a small amount of solvents should be out
for use and solvents should be purchased in the smallest
quantities practical in order to minimize fire hazards. Before
starting work, all sources of ignition should be eliminated. See
the CSA checklist on storage and use of flammable and combustible
One of the most important precautions in silk screen printing
is proper ventilation. Research conducted by the Harvard
University School of Public Health in a university silk screen
printing classroom, showed that printing without adequate
ventilation causes exposure to very hazardous levels of the
solvents used. All processes producing solvent vapors --
including printing, drying and screen washing -- should be done
with local exhaust ventilation.
During the printing process, the best type of ventilation
would be an explosion-proof slot exhaust hood located at the rear
of each printing station. The drying rack should be enclosed on
the back, sides, and top, and the solvent vapors exhausted from
the rear. For example, an explosion-proof window exhaust fan can
ventilate the drying racks, if the enclosed rack is placed right
in front of the window.
Clean-up can be done at the printing table utilizing the local
exhaust slot hood. Bleach cleaning of the photoemulsion screens
also needs local exhaust ventilation because of the chlorine gas
Air conditioners do not adequately ventilate screening
processes because they recirculate air rather than exhausting it.
(Even when air conditioners are set on "exhaust" they recirculate
about 95 per cent of the air). Likewise, open windows or doors
are not adequate ventilation for solvent-based silk screen
A National Institute of Occupational Safety and Health
(NIOSH)-approved respirator with organic vapor cartridges can
help minimize exposure to screen printing solvent vapors if
ventilation is not adequate. Sources for respirators and rules
for selection and use of respirators are included in the Center
for Safety in the Arts (CSA) data sheet on Respirators (see CSA
To prevent eye irritation caused by splashes, wear lightweight
plastic splash goggles while pouring or working with paint
removers. Choose goggles which are approved by the American
National Standards Institute (stamped with a "Z87"). These can be
found in most chemistry supply houses and safety equipment stores
and some hardware stores. If ink or other hazardous material is
splashed in the eyes, flood the eyes with water for at least 15
minutes and call a physician. A source of clean water (e.g.
eyewash fountain) should be accessible for this purpose.
Gloves should be worn during all screen printing processes to
protect the skin from hazardous pigments, solvents and other
chemicals. Ordinary rubber dishwashing gloves or surgical gloves
will not provide adequate protection. All gloves do not provide
protection against the same materials. When using inks, gloves
that protect against aromatic solvents and petroleum distillates
should be used. Lacquer use requires wearing gloves that protect
against ketones and alcohols besides aromatics and petroleum
You should find out the type of solvents in the
products you use by consulting the specific MSDSs. (For further
information on gloves, consult the CSA "Glove Selection" data
sheet). To further decrease the risk of skin contact wear long
pants, a long sleeved shirt and an apron.
Solvent-soaked rags should be stored in approved oily waste
cans which are emptied daily. Disposal should be done in
accordance with local city and fire regulations, and an approved
waste-disposal firm may be necessary for large quantities of
solvent waste. Never pour solvents down the drain. Small
quantities of solvents can be evaporated under a fume hood or
WATER-BASED SCREEN PRINTING
Because of the extremely high cost of providing adequate local
exhaust ventilation systems in classroom situations, there has
been a switch to water-based screen printing products. In recent
years the quality of these inks has improved remarkably, and many
professional artists as well as printing studios have switched to
water-based products. Flat, opaque, hard-edged traditional
looking prints are still possible, and dye-like transparencies
and washes rivaling watercolor and lithography can also be
produced. The same wide variety of stencils can be used with
this medium as with the solvent-based inks.
The changing over to water-based inks means the incorporation
of a whole new system and requires understanding of this new
medium. It is necessary to take time and learn how to produce
After learning how to work with water-based
products, artists and instructors report that the colors are
beautiful, the inks don't dry on the screen, and paper designed
specifically for water-based screen stays flat. In addition the
overall cost of printing with water-based silk screen inks is
cheaper than with solvent-based inks because water is used for
cleanup rather than the more expensive solvents.
The inks and cleaning materials employed in water-based screen
printing use water instead of toxic organic solvents. Airborne
organic vapors, skin absorption of organic solvents and the risk
of fire are greatly reduced. Small amounts of organic solvents
may be used in water-based screen printing inks.
We recommend products with only water, propylene glycol or ethylene glycol.
Glycol ethers such as cellosolve are much more hazardous since
they can cause anemia, kidney damage, and adverse reproductive
effects such as miscarriages, birth defects, testicular atrophy
and sterility. It is necessary to get material safety data
sheets (MSDSs) on all products in order to ascertain the ink
composition, since the ingredients are not always listed on the
Use of diazo photoemulsions can completely eliminate the need
for solvents. If lacquer stencils are used, then the hazards
discussed earlier for solvents will apply, although to a lesser
extent since smaller amounts of solvents are used.
Basic personal hygiene is a must for all those working with
art materials. Water-based screen printing is no exception.
There should be no eating, drinking, smoking or make-up
application in the studio or while working.
Hazardous pigments and some toxic solvents are still used in the manufacture of
water-based inks and related materials. To avoid ingestion and
absorption of these substances through skin contact, wearing
gloves is recommended while working in this medium. For water-
based printing, a window exhaust fan should provide adequate
ventilation and costs much less than a slot exhaust hoods or
other complicated ventilation systems. If lacquer stencils are
used, then one explosion-proof slot exhaust hood would be needed
for this process.
Babin, A. and Rossol, M: "Glove Selection". Center for
Safety in the Arts, New York (1988).
Clark N, Cutter T, and McGrane J: Ventilation. Nick Lyons
Books New York (1984).
Johnson LM and Stinnett H: Water-based Inks: A Screenprinting
Manual for Studio and Classroom. Philadelphia Colleges of the
Arts Printmaking Workshop (1987).
McCann M: Artist Beware: The Hazards and Precautions in
Working with Art and Craft Materials. Watson-Guptill, New York
McCann M: "Silk Screen Printing Hazards." Art Hazards News
McCann, M: "Respirators". Center for Safety in the Arts, 1988.
SOURCES OF ADDITIONAL HELP
Written and telephoned inquiries about health hazards in the
arts will be answered by the Art Hazards Information Center of
the Center for Safety in the Arts (formerly the Center for
Occupational Hazards). Permission to reprint this data sheet may
be requested in writing from the Center. For a copy of our
publications list, send a self-addressed, stamped envelope to:
Center for Safety in the Arts, 5 Beekman Street, New York, NY
10038. Telephone 212/227-6220.
This data sheet was revised with the assistance of a grant
from Special Projects, Visual Arts Program of the National
Endowment for the Arts. The Center for Safety in the Arts is
partially supported with public funds from the National Endowment
for the Arts, the New York State Council on the Arts, and the New
York City Department of Cultural Affairs.
(c) Copyright Center for Safety in the Arts 1988
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