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General Chemical
Relief and Other Printing Processes

General Chemicals


Acids are used in intaglio 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.


  • 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.
  • Hydrofluoric acid will cause severe deep burns which require medical attention.
  • Concentrated nitric acid can react explosively with other concentrated acids, solvents, etc. Nitric acid gives off nitrogen oxide gases, which are lung irritant and cause emphysema.


  • Know what is used. Obtain the MSDS for all acids, if possible avoid concentrated acids.
  • Acid etching requires working in an enclosed hood or exhaust unit.
  • Store concentrated nitric and chromic acids away from organic materials. Concentrated nitric acid should always be stored separately from other acids.
  • Always add acid to the water when diluting, never the reverse.
  • Wear appropriate gloves, goggles and a protective apron or lab coat when handling acids.
  • If 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.


Intaglio, lithography and relief inks consist of pigments suspended in linseed oil or water. There can be additional hazardous binders or preservatives, etc.


  • Linseed oil is not considered a hazard, but may contain small amounts of heavy metals.
  • Ink oils are flammable and soaked rags may ignite by spontaneous combustion.


  • Obtain the MSDS on all products used. Use the least toxic inks possible.
  • Do not use an open flame near or to heat oils and varnishes.
  • Place oil-soaked rags in designated disposal cans.


Pigments are the colorants used in lithography, intaglio, and relief printing inks. There are two types of pigments: inorganic pigments, and organic pigments.


  • Pigment poisoning can occur if pigments are inhaled or ingested.
  • The classic example of a toxic inorganic pigment is lead chromate (chrome yellow). Other inorganic pigments may be hazardous including pigments based on cobalt, cadmium, and manganese. All can cause cancer and organ damage.
  • 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 may cause skin ulceration and allergic skin reactions.


  • Obtain MSDS on all pigments, the label may not turely represent the pigments present.
  • Use the safest pigments possible. Avoid lead pigments.
  • Avoid mixing dry pigments whenever possible [see painting]


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 hands.


  • Repeated contact with solvents can cause absorption, defatting of skin and dermatitis.
  • Concentrated vapors can cause dizziness, nausea, fatigue, loss of coordination, or coma.
  • Many solvents are toxic if ingested. Swallowing an ounce of turpentine can be fatal.
  • Most solvents are also flammable.


  • Obtain the MSDS on all solvent products used. Use the least toxic solvent possible. Replace the more toxic methyl alcohol with denatured or isopropyl alcohol.
  • Use adequate ventilation.
  • Keep minimum amounts of solvents on hand and purchase in practical container size. Store solvents or solvent-containing materials in a flammable storage cabinet.
  • Never store solvents or solvent-containing materials in food or drink containers.
  • Do not allow smoking, open flames or other sources of ignition near solvents.
  • Wear gloves when handling solvents to avoid skin contact. Use baby oil to clean your hands instead of solvents.


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 involves use of dilute nitric acid, Dutch mordant or ferric chloride to etch the zinc or copper plate. Varnishes containing ethyl alcohol, grounds containing asphaltum or gilsonite and mineral spirits, rubber cement, and rosin or spray paints are used.


  • See Solvents section for the hazards of solvents.
  • See Acids section for the hazards of acids. Nitrogen dioxide and flammable hydrogen gas is also produced during the etching process.
  • Concentrated nitric acid is a strong oxidizing agent and can react with many other chemicals to cause fire.
  • Mixing 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 and on heating it can violently decompose to oxygen and potassium chloride.
  • Rosin and asphaltum dust is combustible. Rosin dust may cause asthma and dermatitis.
  • Inhalation of solvents and pigments can result from use of aerosol spray paints.


  • Obtain the MSDS for all materials used.
  • Use Dutch mordant with extreme caution. A safer substitute for etching copper is ferric chloride. Ferric solution might cause minor skin irritation from prolonged contact.
  • Application of grounds or stopouts should be done with local exhaust ventilation.
  • Acid etching should be done with local exhaust ventilation. See section on precautions for Acids for more information.

Other Techniques

Drypoint, mezzotint and engraving use sharp tools to incise lines in metal plates.


  • On hazard with these types of processes involves accidents with sharp tools.
  • Long-term use of these tools can cause carpel tunnel syndrome.


  • 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.


  • 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.
  • Lithotine, turpentine, or oil-soaked rags can be a fire hazard if not in metal container.


  • Respirators with organic vapor cartridges can be used in absence of ventillation.


Lithography uses zinc and aluminum metal plates or stones for printing. It involves a variety of chemicals to make the image areas receptive to water and ink-repellent.

Plate and Stone Preparation

A variety of drawing materials with high wax and fatty acids are used to make the image. 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) and a variety of solvents including lithotine, gasoline, kerosene, and mineral spirits are used.


  • Acids used include phosphoric, nitric, acetic, hydrochloric, hydrofluoric and tannic.
  • The concentrated acids are corrosive and all solutions cause skin irritation from repeated contact. Hydrofluoric acid and phenol are the most dangerous.
  • Lithotine, kerosene, and mineral spirits are skin and eye irritants; inhalation causes 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 a thinner.
  • Dichromate salts cause skin and nasal ulceration, are allergens and suspect carcinogens.
  • Rosin dust may cause asthma and allergic dermatitis. There is the hazard of explosion from the buildup of rosin dust.
  • 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.


  • Obtain the MSDS for all materials used.
  • See Acids or 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 solutions. Do not use hydrofluoric acid or phenol.
  • Appropriate gloves, goggles and a protective apron should be worn when 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.


  • Some roller cleaners and glaze cleaners contain perchloroethylene and methylene chloride.
  • Most chlorinated solvents (except 1,1,1-trichloroethane) have been shown to cause liver cancer in animals. In addition perchloroethylene causes liver damage and methylene chloride, heart attacks.


  • Obtain the MSDS for all solvents. See Solvents section for the precautions.
  • 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 with ventilation is sufficient.

Relief and Other Printing Processes

Processes include relief printing, collagraphs, monoprints, and plastic prints.


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.


  • Rubber cement is extremely flammable and most rubber cements contain n-hexane which can cause damage to the peripheral nervous system 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.


  • Know the hazards of materials used. Obtain the MSDS 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.
  • Wear gloves when using epoxy glues.
  • Wear a NIOSH-approved toxic dust respirator when sanding collagraph plates.


Monoprints involve standard intaglio, lithographic and other printmaking techniques, but only one print is made. The same precautions should be taken as parent techniques.


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).


  • 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.
  • 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.


  • 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, see photolitho section.
  • Use presensitized plates if possible.
  • Use photoresist solutions with local exhaust ventilation or an organic vapor respirator. Wear butyl rubber gloves when handling KPR solutions.


Photolithography involves transferring graphic images to stones or 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. Diazo-sensitizing solutions, developers with highly toxic solvents, plate conditioners containing strong alkali and other mixtures are used for metal plates.


  • 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 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.
  • Solvents in developing solutions are highly toxic both by inhalation and skin absorption.


  • Obtain a MSDS for all materials used.
  • See Solvents section for more precautions.
  • Avoid ammonium dichromate and use presensitized plates if possible. If you cannot substitute, wear gloves and goggles. Store it away from heat, solvents and organics.
  • 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 chemicals.


Photoprintmaking involves exposing a light-sensitive emulsion or film to ultraviolet light shining through an opaque image, transferring the image to a plate.

Plastic Prints

Plastic prints can involve making prints from a wide variety of plastics and resins.


  • Plastic prints can involve hazards from inhalation of plastic resin vapors and decomposition fumes from drilling, machining and sawing.


  • Obtain the MSDS for all materials used.
  • See Solvent section for the precautions.
  • Use the least toxic material available.

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.


  • Some woods, particularly tropical hardwoods, can cause skin irritation and/or allergies.
  • Sharp carving tools can result in cuts.
  • Wood carving can cause carpel tunnel; discussed earlier in drypoint and mezzotint.
  • Caustic soda (sodium hydroxide) can cause skin burns and eye damage if splashed.
  • Eating, drinking or smoking while printing can result in accidental ingestion of pigments.
  • Hazardous solvents are used in stopouts, resists and for cleaning. See Solvents section for more information on the hazards of solvents.


  • Obtain the MSDS for all materials used.
  • See Acids and Solvents sections for precautions.
  • 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 behind the tool.
  • Carpel tunnel syndrome can be minimized or avoided by using tools with wide handles, avoiding tight grips and allowing rest periods with hand flexing exercises.