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SECTION 13: Lithography and Relief Printing
General Chemicals (top)
Inks
Intaglio, lithography and relief inks consist of pigments
suspended in either linseed oil or water as a vehicle.� There can be additional hazardous binders or
preservatives, etc.
Hazards
- Oil-based inks contain treated linseed oils.� While linseed oil is not considered a hazard
by skin contact or inhalation, ingestion of large amounts of some treated
linseed oils might be hazardous due to presence of small amounts of
toxic heavy metals.� Oil vehicles
are flammable when heated, and rags soaked in these may ignite by spontaneous
combustion.
Precautions
- Know what materials are used.� Obtain
the material safety data sheets (MSDSs) on all products used.� Use the least toxic inks possible.�
- Do not use an open flame to heat linseed oil, linseed oil, varnishes,
or burnt plate oil.� Take
normal fire prevention measures (e.g. no smoking or open flames
in work area).
- Place oil-soaked rags in self-closing disposal cans and remove
from the studio each day.� An
alternative is to place the oil-soaked rags in a pail of water.
Pigments
Pigments are the colorants used in lithography, intaglio,
and relief printing inks.� There
are two types of pigments: inorganic pigments, and organic pigments.
Hazards
- Pigment poisoning can occur if pigments are inhaled or ingested.� For normal printing with prepared inks, the
main hazard is accidental ingestion of pigments due to eating,
drinking or smoking while working, or inadvertent hand to mouth
contact.
- The classic example of a toxic inorganic pigment in printmaking
is lead chromate (chrome yellow).� Lead
pigments can cause anemia, gastrointestinal problems, peripheral
nerve
damage (and brain damage in children), kidney damage and
reproductive system damage.� Other inorganic pigments may be hazardous
also, including pigments based on cobalt, cadmium, and manganese.�
- Some of the inorganic pigments, in particular cadmium pigments, chrome
yellow and zinc yellow (zinc chromate) may cause lung cancer if inhaled.� In addition, lamp black and carbon black may
contain impurities that can cause skin cancer.
- Chromate pigments (chrome yellow and zinc yellow) may cause
skin ulceration and allergic skin reactions.
- The long-term hazards of the modern synthetic organic pigments
have not been well studied.
Precautions
- Obtain MSDSs on all pigments.� This
is especially important because the name that appears on label
of the
color may or may not truly represent the pigments present.
- Use the safest pigments possible.� Avoid lead pigments.
- Avoid mixing dry pigments whenever possible.� If dry pigments are mixed, wear a NIOSH-approved
toxic dust respirator.
Solvents
In general, organic solvents are one of the most underrated
hazards in art materials.� Organic
solvents are used in printmaking to dissolve and mix with oils, resins,
varnishes, and inks; and to clean plates, rollers, tools, and even hands.�
Hazards
- Repeated or prolonged skin contact with solvents can cause defatting
of the skin and resultant dermatitis.� Many solvents can also be harmful through skin absorption.
- Inhalation of solvent vapors is the major way in which solvents
are harmful.� High concentrations
of most solvents can cause dizziness, nausea, fatigue, loss
of coordination, or coma.� This
can also increase the chances for mistakes and accidents.
- Many solvents are toxic if ingested. Swallowing an ounce of
turpentine can be fatal.
- Most solvents, except chlorinated hydrocarbons, are also either
flammable or combustible.�
Precautions
- Obtain the MSDS on all solvent products used.�
Use the least toxic solvent possible.�
For example, replace the more toxic methyl alcohol with denatured
alcohol or isopropyl alcohol.�
- Use adequate ventilation.�
- Keep minimum amounts of solvents on hand and purchase in smallest
practical container size.� Large
amounts of solvents or solvent-containing materials should
be stored in a flammable storage cabinet.
- Never store solvents or solvent-containing materials in food
or drink containers. Always label containers.
- Do not allow smoking, open flames or other sources of ignition
near solvents.
- Have a class B fire extinguisher in the area.�
(If ordinary combustible materials are present, you
may need a Class ABC fire extinguisher).
- Wear gloves when handling solvents to avoid skin contact In
particular do not use solvents to clean ink off hands.�
Baby oil is a good substitute.�
Acids
Acids are used in intaglio (acid etching) and in lithography.�
Strong acids commonly used include nitric acid, hydrochloric acid,
and phosphoric acid, and less commonly carbolic acid (phenol), chromic
acid, hydrofluoric and sulfuric acids.
Hazards
- Concentrated acids are corrosive to the skin, eyes, respiratory system
and gastrointestinal system.� Dilute acids can cause skin irritation on repeated or prolonged
contact.�
- Chromic acid is a skin sensitizer, suspect carcinogen, and oxidizer.
- Phenol is highly toxic by skin absorption and ingestion.� It may cause severe kidney damage, central
nervous system effects and even death if absorbed in large
amounts.
- Hydrofluoric acid is highly toxic and can cause severe, deep
burns which require medical attention.� There
is no immediate pain warning from contact with hydrofluoric
acid.
- Concentrated nitric acid is a strong oxidizing agent and can
react explosively with other concentrated acids, solvents, etc.� Nitric acid gives off various nitrogen oxide
gases, including nitrogen dioxide which is a strong lung irritant
and
can cause emphysema.
Precautions
- Know what is used.� Obtain
the MSDS for all acids.�
- Whenever possible avoid concentrated acids.�
- Doing acid etching requires working in a enclosed hood, or in
front of a slot exhaust hood or window exhaust fan at work
level.
- Store concentrated nitric and chromic acids away from organic
materials.� Concentrated nitric acid should always be
stored separately even from other acids.�
- An important safety rule when diluting concentrated acids is
to add the acid to the water, never the reverse.
- Wear appropriate gloves, goggles and protective apron or lab
coat when handling acids.
- If adequate ventilation is not available, wear a NIOSH-approved
respirator with acid gas cartridges.
- If acid is spilled on your skin, wash with lots of water.� In case of eye contact, rinse the eyes with
water for at least 15-20 minutes and seek medical attention.�
Lithography (top)
Lithography uses either zinc and aluminum metal plates
or stones for printing.� It involves
use of a variety of chemicals to make the image ink-receptive and non-image
areas receptive to water and ink-repellent.
Plate and Stone Preparation
A variety of drawing materials with high wax and fatty
acid content are used to make the image, including tusche and lithographic
crayons.� Airbrushing liquid drawing
materials or using spray enamel or lacquer is also common.� Other materials used in stone or plate processing
include etch solution containing acids and gum arabic, counteretch solutions
containing acids and sometimes dichromate salts, and fountain solutions
containing dichromate salts.� Phenol
(carbolic acid) has been used for removing grease from stones, and a variety
of solvents including lithotine, gasoline, kerosene, and mineral spirits,
which are used for diluting drawing materials, washing out images and
correction of images.� Talc and
rosin mixtures are also used.� Metal
plates are prepared with solvent-based vinyl lacquers.
Hazards
- Acids used include phosphoric, nitric, acetic, hydrochloric, hydrofluoric
and tannic acids.� The
concentrated acids are corrosive and even dilute acid solutions
can cause skin irritation
from prolonged or repeated contact. Hydrofluoric acid and
phenol are the most dangerous to use.
- Lithotine, kerosene, and mineral spirits are skin and eye
irritants and inhalation can cause intoxication and respiratory
irritation.
- The solvents contained in vinyl lacquers can include highly
toxic isophorone and cyclohexanone. Methyl ethyl ketone (MEK),
which is moderately
toxic, is often used as a thinner.
- Dichromate salts may cause skin and nasal ulceration and allergic
reactions, and are suspect cancer-causing agents.
- Rosin dust may cause asthma and allergic dermatitis.�
There is the hazard of explosion from the buildup of
rosin dust, in enclosed rosin boxes, around an ignition source.�
- Talcs may be contaminated with asbestos and silica.
- Airbrushing drawing materials or using spray enamel paints
is more hazardous than drawing with a brush because the inhalation
hazard is
higher.
Precautions
- Obtain the MSDS for all materials used.
- See Acids and Solvents sections for the precautions with acids
and solvents.
- Use the least toxic solvents.� Gasoline
should never be used.� Lithotine
and mineral spirits are less toxic than the more irritating
kerosene.
- Use asbestos-free talcs such as baby powders.
- Avoid dichromate-containing counteretches and fountain solutions
if possible.� Do not
use hydrofluoric acid or phenol.
- Appropriate gloves, goggles and a protective apron should
be worn when mixing or using concentrated acids.
Printing and Cleanup
For all types of lithographic inks, solvents are used
to make image corrections on the press, to remove images, and to clean
the press bed and rollers.
Hazards
Some roller cleaners and glaze cleaners can contain chlorinated
hydrocarbons such as perchloroethylene and methylene chloride.� Most chlorinated solvents (except 1,1,1-trichloroethane)
have been shown to cause liver cancer in animals and are therefore suspect
human carcinogens.� In addition
perchloroethylene can cause liver damage, and methylene chloride heart
attacks.�
Precautions
- Know materials used.� Obtain
the MSDS for all solvents.� See
Solvents section for the precautions with solvents.
- Choose products that do not contain chlorinated solvents whenever
possible.
- For small scale solvent use in correcting images or cleaning
the press bed using lithotine or mineral
spirits, dilution ventilation (e.g. window exhaust fan) is
sufficient.
Intaglio is a printmaking process in which ink is pressed
into depressed areas of the plate and then transferred to paper.� These depressed areas can be produced by a
variety of techniques, including acid etching, drypoint, engraving and
mezzotint.
Etching
Etching involves use of dilute nitric acid, Dutch mordant
(hydrochloric acid plus potassium chlorate) or ferric chloride to etch
the zinc or copper (respectively) metal plate.�
Unetched parts the plate are protected with resists such as stopout
varnishes containing ethyl alcohol, grounds containing asphaltum or gilsonite
and mineral spirits, rubber cement, and rosin or spray paints for aquatinting.�
Sometimes, soft grounds contain more toxic solvents.
Hazards
- See Solvents section for the hazards of solvents.�
1,1,1- trichloroethane found in some soft grounds is moderately
toxic by inhalation under normal conditions but may cause fatalities
at very high concentrations.
- See Acids section for the hazards of acids.�
In particular nitric acid etching releases the respiratory
irritant nitrogen dioxide which has poor odor warning properties.
During the
etching process, flammable hydrogen gas is also produced.
- Concentrated nitric acid is a strong oxidizing agent and can
react with many other chemicals, especially solvents or other organic
compounds,
to cause a fire.
- Mixing hydrochloric acid with potassium chlorate to make Dutch
mordant produces highly toxic chlorine gas. Potassium chlorate
is a key ingredient
in many pyrotechnics, and is a potent oxidizing agent.�
It can react explosively with organic compounds,
sulfur compounds, sulfuric acid or even dirt or clothing.�
On heating it can violently decompose to oxygen
and potassium chloride.� Storage
and use are very dangerous require special precautions
especially
when mixing.
- Rosin dust (and asphaltum dust which is also sometimes used)
is combustible.� Sparks or static electricity have caused explosions
in enclosed rosin and aquatint boxes.� Rosin dust may also cause asthma and dermatitis in some individuals.�
- Inhalation of solvents and pigments can result from use of aerosol
spray paints.
Precautions
- Obtain the MSDS for all materials used.
- See Solvents and Acids sections for specific precautions.
- Use Dutch mordant with extreme caution.�
A safer substitute for etching copper plates is ferric
chloride (iron perchloride).� This forms acidic solutions so should be handled
accordingly, but does not have the dangers of handling concentrated
acids.� Ferric chloride
solution might cause minor skin irritation from prolonged
contact.
- Application of grounds or stopouts should be done with local
exhaust ventilation, (e.g. slot or enclosed hood).
- Acid etching should be done with local exhaust ventilation.� See section on precautions for Acids for more
information. Rosin (or asphaltum) boxes should be explosion-proof.� Use sparkproof metal cranks, explosion-proof
motors, or compressed air.� Don't
use hair dryers to stir up rosin dust.�
Other Techniques
Drypoint, mezzotint and engraving use sharp tools to
incise lines in metal plates.�
Hazards
- One major hazard associated with these types of processes involves
accidents with sharp tools.
- Long-term use of these tools can cause carpel tunnel syndrome,
which can cause numbness and pain in the first three fingers.� Severe cases can be incapacitating.
Precautions
- Keep tools sharp, store them safely and always cut away from yourself.�
- When possible, clamp down plates to avoid slippage.
- Minimize the chance of carpel tunnel syndrome by choosing tools
with wide handles, avoiding tight grips, and doing hand flexing
exercises during regular rest periods.� Set
work table height so wrist flexing motions are minimal.
Printing and Cleanup
Intaglio inks contain pigments, treated linseed oil and
modifiers.� Printing involves placing
the ink on the inking slab, inking the plate by hand, and then printing.� Cleanup of inking slab, press bed, and cleaning
the plate is done with a variety of solvents including mineral spirits,
alcohol, lithotine, turpentine, etc.
Hazards
- Preparing your own inks from dry pigments can involve inhalation
of toxic pigments.� See Pigments section for the hazards of pigments.
- See Solvents section for the hazards of solvents.�
Plate cleaning is more hazardous than cleaning inking
slabs or press beds because larger amounts of solvents are
used.
- Lithotine, turpentine, or oil-soaked rags can be a spontaneous
combustion hazard if improperly stored.
Precautions
- See Pigments and Solvents sections for the specific precautions
for pigments and solvents.
- NIOSH-approved respirators with organic vapor cartridges can
be used if ventilation is not adequate.
Relief and Other Printing Processes (top)
Other printing processes include relief printing, collagraphs,
monoprints, and plastic prints.
Relief Printing
Relief printing techniques include woodcuts, linoleum
cuts and acrylic plates for plaster relief.�
These techniques involve the cutting away of plate areas that are
not to be printed.� Relief inks
can be oil-based or water-based.
Hazards
- Some woods used for woodcuts can cause skin irritation
and/or allergies. This is particularly true of tropical hardwoods.
- Accidents involving sharp tools can result in cuts.
- Wood carving and cutting tools can cause carpel tunnel syndrome.�
This was discussed earlier in the section that included
drypoint and mezzotint.
- Caustic soda (sodium hydroxide) is sometimes used for etching
linoleum.�
It can cause skin burns and severe eye damage if splashed
in the eyes.�
- Eating, drinking or smoking while printing can result in accidental
ingestion of pigments.
- Hazardous solvents are used in stopouts and resists in linoleum
etching, and for cleaning up after printing with oil-based
inks.� See Solvents section for more information
on the hazards of solvents.
Precautions
- Obtain the MSDS for all materials used.
- See Acids and Solvents sections for precautions with acids
and solvents.�
- Water-based inks are preferable to oil-based inks since solvents
are not needed.
- Wear appropriate gloves, goggles and protective apron when
handling caustic soda.
- If the chemical is spilled on your skin, wash with lots of
water.�
In case of eye contact, rinse the eyes with water for
at least l5-20 minutes and contact a physician.�
- Always cut in a direction away from you, with your free hand
on the side or behind the hand with the tool.
- Carpel tunnel syndrome can be minimized or avoided by using
tools with wide handles, avoiding tight grips, and rest periods
with hand
flexing exercises.� Linoleum
cutting is softer to work, and thus can reduce musculoskeletal
injury.
Collagraphs
Collagraphs are prints produced by using a collage of
different materials glued onto a rigid support.�� A wide variety of materials and adhesives can be used in making
collagraphs.
Hazards
- Rubber cement, a common adhesive used with collagraphs, is
extremely flammable and most rubber cements and their thinners
contain the
solvent
n-hexane which can cause damage to the peripheral nervous
system (hands, arms, legs, feet) from chronic inhalation.
- Epoxy glues can cause skin and eye irritation and allergies.
- Spraying fixatives on the back of collagraph plates to seal
them can involve risk of inhalation of the solvent-containing
spray mist.
- Sanding collagraph plates which have been treated with acrylic
modeling compounds or similar materials can involve inhalation
of irritating
dusts.
Precautions
- Know the hazards of materials used.�
Obtain the MSDSs from the manufacturer.�
- Use the least toxic materials available.�
In particular use water-based glues and mediums (e.g. acrylic
medium) whenever possible.� Some
rubber cements are made with the solvent heptane, which is less toxic
than n-hexane, primarily because peripheral neuropathy is not associated
with its use.�
- Wear gloves when using epoxy glues.
- Wear a NIOSH-approved toxic dust respirator when sanding collagraph
plates.
Plastic Prints
Plastic prints can involve making prints from a wide
variety of plastic materials and resins.�
Hazards
Plastic prints can involve hazards from inhalation of
plastic resin vapors (e.g. epoxy resins) and also from inhalation of decomposition
fumes from drilling, machining, sawing, etc. of finished plastics.
Precautions
- Obtain the MSDS for all materials used.
- See Solvent section for the precautions with solvents.
- Use the least toxic material available.
Monoprints
Monoprints involve standard intaglio, lithographic and
other printmaking techniques, but only one print is made.� Monoprints have the same hazards involved in plate preparation and
printing as the parent techniques.
Photoprintmaking
Photoprintmaking involves exposing a light-sensitive
emulsion or film to ultraviolet light through a transparent support containing
an opaque image to transfer the image to a plate.� The transparency through which the photoemulsions are developed
can include drawings on a transparent support such as Mylar or acetate,
or photographic images processed on graphic arts film to yield a positive
image.� Several photoprintmaking
methods will be discussed.
Photolithography
Photolithography involves transferring graphic images
to stones or metal plates that are coated with a light-sensitive emulsion.� One can coat the stone or metal plate, or use
presensitized metal plates.� Light-sensitive
emulsions used on stone consist of a mixture of powdered albumin, ammonium
dichromate, water, and ammonia; commercial emulsions are usually based
on diazo compounds.� Developing
solutions for these mixtures often contain highly toxic solvents.�
Diazo-sensitizing solutions, developers with highly toxic solvents,
plate conditioners containing strong alkali, and other brand name mixtures
are used for metal plates.�
Hazards
- Diazo photoemulsions are the least hazardous although they can cause
eye irritation.�
- Ammonium dichromate used for stone is a probable human carcinogen,
is moderately toxic by skin contact, and may cause allergies, irritation,
and external ulcers; it is highly flammable and a strong oxidizer.�
- Ammonia is a skin irritant and highly toxic by inhalation.� Ammonia is highly corrosive to the eyes.� It has good odor-warning properties.
- Light exposure sources include photoflood lamps, vacuum Poly-
Lite units, and carbon arcs.� Carbon
arcs produce large amounts of ultraviolet radiation which
can cause skin and eye damage and possible skin cancer.�
Carbon arcs also produce hazardous metal fumes, and
ozone and nitrogen dioxide (which can cause emphysema), and
toxic carbon
monoxide.�
- Screen cleaning solutions include strong caustic solutions, enzyme
detergents which can cause asthma, and chlorine bleach.�
These are skin and respiratory irritants.
- Many solvents used in developing solutions are highly toxic
both by inhalation and skin absorption.
Precautions
- Obtain a MSDS for all materials used.
- See Solvents section for more precautions with solvents.
- Avoid ammonium dichromate and use presensitized plates if
possible.�
If you cannot substitute, wear gloves and goggles.�
Store it away from heat, solvents and other organic materials.
- Use ammonia solutions or solvent-containing photolithographic
solutions inside a laboratory hood, or in front of a slot
exhaust hood.� Wear gloves, goggles, and if ventilation is
inadequate, a respirator.
- Do not use carbon arcs unless they are equipped with local
exhaust ventilation exhausted to the outside.�
Quartz mercury or metal halide lamps are safer.
- Wear gloves, goggles and plastic apron or laboratory coat
when mixing hazardous chemicals
Photoetching
Photoetching is usually done using the KPR products.� Photoresist dyes often contain a variety of
highly toxic solvents, including ethylene glycol monomethyl ether acetate
(2-ethoxyethyl acetate, cellosolve acetate), ethylene glycol monoethyl
ether, and xylene, and benzaldehyde.�
The developers contain xylene and ethylene glycol monomethyl ether
acetate (2-methoxyethyl acetate or methyl cellosolve acetate).�� Developers used for safer presensitized plates
also also contain solvents.� Exposure
of the plate is done with ultraviolet sources such as carbon arcs, mercury
lamps, or metal halide lamps.
Hazards
- See the Solvents section for the hazards of various solvents.� In particular, methyl and ethyl ether acetates
of ethylene glycol are highly toxic by skin absorption and inhalation
and can cause anemia, kidney damage, testicular atrophy and sterility
in men, and miscarriages and birth defects in pregnant women.�
- Xylene is moderately toxic by skin absorption, and highly toxic by
inhalation and ingestion.� It
is a strong narcotic.
- The Photolithography section discusses carbon arc hazards.
Precautions
- See Solvents section for precautions with solvents.
- Pregnant or nursing women, children, and men trying to conceive
should not work with these materials.
- Use photofloods or other light sources instead of carbon arcs.� Precautions with carbon arcs is discussed
in the Photolithography section.
- Use presensitized plates if possible.
- Use photoresist solutions with local exhaust ventilation,
or wear an organic vapor respirator.� Wear
butyl rubber gloves when handling KPR solutions.
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