Nontoxic Printmaking, Safe Painting & Printed Art

Acrylic Resist Etching                           
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Three Media in One

Intaglio Printmaking is not just a particular way of creating images, of working in a sculptural way, or of making prints, but all of those things in a single process. A blank plate becomes the basis for virtually limitless creativity, employing a variety of tools and methods to produce marks with great breadth of expression.The grooves, indentations, ridges, scars and scratches produced by intaglio mark making turn the flat surface of the plate into a textured, eroded landscape. These lines, textures and tonal areas are fully revealed in the final intaglio print. The Acrylic Resist Etching system makes use of three key methods to produce marks on a metal plate: dry techniques, etch techniques and collagraph. These can be used independently or in combination.

In the more mechanical or dry techniques, indentations on the hard surface are made by the artist using a variety of metal working tools, such as a drypoint needle, pieces of sandpaper, or even an electric engraving tool. With the etch techniques the process is more indirect. The artist creates mordant resistant deposits on the plate so that the corrosive bath can erode exposed areas of metal, which will then hold ink. Thirdly, there are the collagraph or building-up processes in which additional layers are added to a plate. Due to their toughness, acrylics are highly suitable for this approach. Most of the new grounds, such as a hard ground or ImagOn, effortlessly stand up to the rigors of etching and of printing. This innovative printing from acrylic intaglio surfaces has the added advantage of easy wiping, and a clean plate tone is much easier to achieve than on a metal surface.

The chosen method(s) selected to create a plate may vary, but the inking, wiping, and printing process is common to all intaglio methods. For more information on inking, wiping and printing, click on the following link:

Electron Micrograph of Acrylic Polymer Chains.
Photo taken at University of Maine during a research collaboration, courtesy of Surface Science Institute U Maine, 1997

The Art of Polymers

Acrylics undergo a dramatic transformation during drying; this is called polymerisation. Tiny acrylic globules, or monomers float individually in a watery emulsion and then link together as the water evaporates. This process can also be aided by the application of gentle heat - by placing the plate in a drying cabinet after the application of acrylics, for example, or by using a hairdryer on the plate.

Polymerisation is complete when the monomers remain firmly linked in long chains, thus turning them into polymers. Once dry, a very tough, plastic-like substance has formed on the metal plate that is both hardwearing, as well as perfectly mordant resistant.
Industry already has a history of exploiting these properties; cars are painted with waterbased paints, and acrylic photo resists - similar to ImagOn film - are used for making printed circuit boards in the electronics industry.

Acrylics and other Polymers and Safety

In the 90s water-based paint products were generally hailed as being THE safe alternative to the then dominant VOC and oil-based systems. Quite a few of the claims of improved safety have been borne out by facts, but the idea of 'intrinsic' safety of water based products and polymers is exaggerated, and may even be misleading. Some manufacturers make acrylic paint and printmaking products with impeccable ingredients, full MSDS documentation and certified lab testing, and have a perfect safety record - such products can be deemed 'nontoxic'. But there are many water-based products that may still carry significant toxicity. Especially cheaper products may contain powerful toxins such as glycol ether, plastic softeners (phthalates), formaldehyde, unreacted volatile monomers, or even traces amounts of benzene. Shockingly, some of the recent safety scares in paints and printing materials are connected to products that were actually marketed as being 'safe' and 'green'. Users are advised to familiarize themselves with safety facts and recommendations beyond manufacturer's claims and advertisements; even MSDS information may be misleading or incorrect.

The illustration shown above was made by etching a brass plate in Edinburgh Etch and printing with Akua inks on Hahnemuehle paper.

The variety of marks, washes and reticulations was created by using a combination of the following resists:

  • oil crayon
  • carborundum Speedball wash
  • Crisco smears
  • dry brush marks
  • Hunt Speedball wash
  • Sharpie
  • Lascaux acrylic paint
  • litho crayon

A Painterly Aesthetic

Over two decades ago Keith Howard started etching with waterbased products. Initially, this move was driven simply by a desire to avoid the toxic hazards of traditional intaglio printmaking. To the great excitement of artists, his explorations showed that acrylics could not only emulate the aesthetic created by conventional etching methods - with ease - but could even extend creative versatility. Traditional intaglio printmaking has a strong linear bias, but is lacking in painterly possibilities. By contrast, Acrylic Resist Etching introduces a new breadth of painterly mark making to the intaglio medium while retaining all of its essential graphic qualities.

Safe Photo Etching for Photographers and Artists
Keith Howard, 1999, Wynne Resources, Alberta
ISBN 0-9695577-0-1

(below) Keith Howard, range of acrylic wash or destruction ground effects from etched copper plates, 1995

The Properties of Acrylics 

Acrylics brushed, poured, rolled, or sprayed onto a metal plate form a strong bond with the plate surface. During etching, acrylics do not tend to chip off along the edges of the eroded intaglio, as is the case with oil-based resists and, if required, can even be left on plates during printing. In the liquid state acrylic grounds can be easily cleaned from brushes or work surfaces with soapy water, but become water and mordant resistant once they have fully hardened.

Acrylics can also acquire self-texturing and tonal qualities when they are diluted rather than used neat. This unique property is exploited in acrylic resist etching techniques such as the "destruction ground" or the diluted SOFT GROUND. Both of these are designed to conjure up reticulated wash effects on the print which resemble lithography or wash painting, whilst infusing them with the depth and crispness that is unique to intaglio printmaking.

The acrylic wash process works like homeopathy: the more diluted the solution the more potent the effect. For a standard acrylic resist wash medium, dilute about 1 part acrylic medium to about 50 parts water. This will yield a black after about an hour of etching in Edinburgh Etch. Lighter tones are created by filling in with more concentrated layers of acrylic medium. The rust  colored Hunt Speedball Screen Filler is Keith Howard's preferred wash medium. Lascaux make a dedicated wash medium which is ideal as a wash resist on zinc and steel plates.


        1 : 50 = Acrylic Wash Medium

The Art of Removing Plastics

It is often thought that plastics are hard to break or dissolve. However, the polymers used in acrylic resist etching are easily broken down and removed by alkaline substances such as sodium carbonate. This is essential for the speedy reclaiming of plates after etching. The alkaline process performing this miracle is known to chemists as saponification. During this chemical transformation the alkaline stripping solution essentially breaks up the polymer chains of tough acrylics and converts them into a harmless soap solution.

Once saturated, the soda ash stripping solution can be safely disposed of (after straining off any remaining solid particles), and may even be re-used as a neutralising agent for a spent etching solution.

Now there are also new kinds of safe solvents based on orange oil, or D-Limonene, that work more like conventional petroleum spirits, but without their health concerns - even hardened acrylics and inks are easily and safely dissolved, layer by layer. For example: ZAcryl D-Solve (see below).

Direct Brush Marks and Open Bite

An image can be created freely on a metal plate by painting marks directly onto the surface with acrylic stop-out varnish. Using brushes of various shapes and sizes will allow you to work in a fluid and painterly way. The thinking you have to apply is typical for many processes in intaglio printmaking: in essence you are regarding the metal plate as an eroded background into which you are shaping islands of light. All the brush marks you apply with stop-out varnish remain raised as non-printing areas, while the areas surrounding them are positive, or open bite, and are turned into the eroded tones and textures that will ultimately transfer ink onto the paper.

This kind of direct etching technique produces very distinct results on different kinds of metal. On copper the image resulting from an open bite is mainly made up of an eroded ridge around the painted marks. On steel the areas surrounding the stopped-out marks turn into dark areas. However, painting on the plate with stop-out varnish is by no means restricted to creating patches on the plate. By adjusting your brushing action in a more dry or streaky fashion you can create lively hatches and textures that can then print as vibrant line work; using quite a stiff, bristly brush is best for this.

You can also try out different dabbing devices like textured rags or sponges soaked in stop-out varnish to add variety to the composition. Whilst the acrylic is wet you can also use a brush handle or a piece of card as a squeegee to draw lines or scrape marks back into the surface. Any stop-out mark that is squeegeed into a very thin layer will produce a tonal effect, not unlike the destruction ground technique.
Pollock-like drips can be made on the plate with an acrylic binder (such as Lascaux 2060, or Golden GAC 200) or a waterbased wood glue.

After etching and stripping the plate, more layers of open bite marks may be repeatedly added to enhance the complexity and depth of the work. The direct mark making approach can also be combined with the destruction ground approach, where tonal wash qualities are produced by diluting the acrylic grounds with water.

There are many more exciting ways of making direct mordant resistant marks on the plate which are strictly speaking open bite techniques; some of these can be etched straight after completing a design on the plate. For instance pre-cut pieces of adhesive tape (acting as mordant resists) can be stuck directly to the metal surface to produce geometric shapes in an etching. Crisp lines of varying thickness can be drawn directly on the plate surface with waterproof felt tip pens. This works because the acrylic ink used in these pens resists corrosion, allowing you to etch away the metal around the drawn lines.

Equally immediate are the many "greasy" materials that can be very successfully used for direct mark making. For example, the mark of a soft wax crayon can give a very textured etched line similar to a crayon line on paper. Mark making with things such as Vaseline or solid vegetable fat (Crisco) is of a more experimental kind, but can be extremely successful for laying a base of etched tone and texture before further definition is given to the plate through another, more controlled, technique.

Similar to diluted acrylics, these materials present a permeable surface that results in variations in the depth of the etch because of the differing thicknesses of the resist layers. This creates a gradation of tones on the print.
The possibilities of this approach are extensive and it is left to the imaginative printmaker to explore and develop his or her own direct etching vocabulary.

Tom Drew, shaped print and plate, 
acrylic resist hard ground etching and 
etched aluminum plate
(Saline Sulfate Etch)

Tailored Acrylic Grounds and Varnishes      

Most acrylic paints and binders may not only be used for painting, but also as etching resists. There are a number of dedicated stop-out varnishes on the market, such as the Golden Acrylic Stop-out Solution which makes a good all-round varnish for etching. For the direct mark making techniques especially, it is well worth utilising a broader range of acrylics as resists - preferably after familiarizing yourself with their creative properties on a sample plate.

The two key properties needed in an acrylic etching ground are (i) good mordant resistance on the one hand and (ii) easy removal after etching on the other. Interesting effects can be etched from directly applied acrylic paint marks, but due to their high pigment content these will eventually break down, causing the plate to foul-bite. Stopping-out with a clear acrylic binder will yield much greater or total mordant resistance, but some strong binders such as Golden GAC 200 or the Badger Aquatint Solution, can be difficult to remove in the soda ash stripping solution.

By contrast, Future floor finish (Johnson's Wax Klear or Klar in Europe), gives both good mordant resistance and is easy to remove; but the fluidity of this product makes it less suitable as a thick stop-out solution for direct mark making. The straightforward technique of using Future as an etching ground was first publicized by Keith Howard in 1991, and since then has become extremely popular in the printmaking world. This clear acrylic represents an ideal etching medium and is used by many contemporary printmakers as their staple hard ground.

During my research at Edinburgh Printmakers, testing a wide range of acrylics, I found a varnish made by Lascaux to be well suited in all its properties as a base ingredient for a number of tailored etching grounds. The product is Lascaux clear gloss varnish 575 - 2060 (mainly available in Europe). Some products, however, do not always including the black coloring often required by etchers.

The varnish 2060 has great mordant resistance on all metals etched in any of the metal salt solutions, whilst being easy to break down in soda ash. The addition of a suitable waterbased coloring or pigment turns the clear varnish into an ideal stop-out varnish for re-etching partial areas of an already bitten plate.

Mixed in equal parts with acrylic paint it makes a stop-out varnish very similar in its painting characteristics to a thick bitumen-based varnish; this is most suitable for the textural direct mark making techniques described earlier. Applied thinly, the 2060 varnish also gives a highly mordant resistant hard ground with very detailed and waxy drawing properties.

      Make up Stop-out varnish for direct mark making as follows:
  1. Fill half a jar with Lascaux clear gloss varnish 575-2060 or Golden GAC 200
  2. Mix with 50% of Lascaux Studio acrylic paint black 526 or similar product


      Make up Stop-out varnish for re-etching as follows:

  1. Use neat Lascaux clear gloss varnish 575-2060
  2. For an opaque ground mix with 10% KOH-I-NOR 3080-4 Universal Ink

Note: Thick layers of acrylic stop-out varnish may need a 10 to 15 minute immersion in a fresh, concentrated soda ash solution to be removed from the etched plate, or use one of the citrus-based solvents (see below). Use a non-scratch scouring pad and hot water to shift all remaining particles.

today, there are numerous ready-made acrylics and resists for printmaking on the market, see links below, or consult the web pages of printmaking suppliers and acrylic paint makers

Hard and Soft Ground

          Safe Stripping with Orange Zest Solvents

Acrylic stop-out can be stripped off in a strong soda ash solution or use one of the excellent citrus-based safe solvents now on the market (such as D*Solve by Z*Acryl) which remove acrylics with great ease.

"This truly revolutionary solvent was formulated as an alternative to petroleum-based turpentines and thinners. It is made from 100% renewable agricultural resources of soy, corn, and citrus, and is non-polluting, non-carcinogenic, and bio-degradable. Less than a teaspoon will thoroughly clean a large plate. DSolve will even strip dried ink from etched lines." Dick Blick

Image: Z*Acryl Product D*Solve


      Make up a Spray Aquatint and Hard Ground (based on this polymer) as follows:

  1. Fill half a clean jar with Lascaux clear gloss varnish 575 - 2060
  2. Add 5 to 10% KOH-I-NOR 3080-4 Universal Ink. Carefully mix the pigment (or acrylic airbrush ink) into the varnish until the mixture reaches opacity. The black ink will not corrupt the mordant resistance of the binder but will make it clearly visible on any metal.
  3. Dilute the mixture with 5 to 15% water to make the spray ink ready for use in an airbrush.

Sprayed as a fine mist the mixture will produce mordant resistant aquatint dots on the plate.
Further passes of the airbrush over the plate result in a finely coated surface, which after 20 minutes of drying makes an ideal, extremely even, malleable and highly responsive hard ground. This sprayed hard ground can be applied directly to a polished and de-greased plate. The varnish does not chip when drawn into and allows for the faithful execution of fine and deep line work, as well as for complex cross-hatching and multiple etching stages.

For more information about about spray aquatint click on the following links:

Aquatint       Intaglio Manual

SAFETY NOTE: a few acrylic products now carry a note warning of a possible cancer hazard;

this may be related to a formaldehyde content (2012)

Protection against low level VOC exposure

Today there are many paint products that are marketed as safe, yet there may still be harmful low-level VOC emissions, such as glycol ether. Examples: many water-based paints, acrylic floor finish, some artist acrylics, low odor, low VOC solvents, and printmaking resists.

Although a full organic respirator may be impractical for a days work we would recommend at the very least wearing a disposable light weight mask that offers some organic vapor protection. Dispose of the mask after a days work (about $ 5 per mask), coupled with use of fans for extraction.

Product example:

3M Particulate Respirator 8514, N95, with Nuisance Level Organic Vapor Relief

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Domestic Paints / Francesco Clemente: Sun, 1980
 Cobra Water-Miscible Oil Paints


Jackson Pollock in his studio, Hans Namuth Estate

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the development of polymer paints came out of
the field of the chemistry of plastics that
emerged in the late 19th century,
so both fields are connected in many ways

below, an in-depth overview,
for additional reference

Plastics in Art:

Safety and Overview


Plastics are used widely in many artistic applications, including: sculpture made from finished or formed plastics, the fabrication of props for theater and film, special effect make up, and plastics are used by museums and galleries in exhibits, displays, transportation and storage of art. 

Working with plastic resins involves chemically linking together many small molecules (monomers) to form the plastic (a polymer), or cross-linking many polymer chains with monomers to form a thermosetting plastic.  Hardeners initiate the reaction.

Catalysts, accelerators, fillers, pigments and dyes, and other additives are also used.  Resins can be molded, cast, laminated, and foamed.

Working with finished plastics involves changing the plastic physically, rather than chemically.  These processes include heating, softening, bending, gluing, machining, sawing, finishing, and similar mechanical processes.

Acrylic Resins

Acrylic resins can be used for both casting plastics and acrylic cements.  There are two types: monomer and monomer/polymer mixtures.  Both types use benzoyl peroxide as the hardener.  The monomer is methyl methacrylate.

Polymerization is carried out at high temperatures which must be controlled carefully.

    1.    Methyl methacrylate monomer is moderately toxic by skin contact, eye contact, and inhalation.  It is an irritant and causes headaches, irritability, and narcosis when inhaled.  It is a common sensitizer, and may cause asthma.
    2.    Benzoyl peroxide hardener is flammable and explosive, and is a slight skin and eye irritant.  See the section on Organic Peroxides later in the chapter for  further  details.
    3.    Finely divided acrylic polymer dust is also a sensitizer.
    1.    Wear gloves and have good local exhaust ventilation when using acrylic resins.  If local exhaust ventilation is not possible, use a window exhaust fan, and wear a NIOSH-approved organic vapor respirator, if needed.
    2.    See section below for more information on peroxides.
    3.    Wear an NIOSH-approved toxic dust mask when handling finely divided acrylic polymer dust.
Amino and Phenolic Resins

Urea-formaldehyde, melamine-formaldehyde, phenol-formaldehyde, and resorcinol-formaldehyde resins are used as thermosetting adhesives and, in the case of phenol-formaldehyde, as a binder in sand casting.  These are usually available as two-component systems with formaldehyde or paraformaldehyde as the hardener.  While urea-formaldehyde and resorcinol-formaldehyde resins can be cured at room temperature, the others require heat.

    1.    Amino and phenolic resins contain formaldehyde, which is highly toxic by inhalation, highly toxic by eye contact and ingestion, and moderately toxic by skin contact.  Formaldehyde is an irritant and strong sensitizer, and is a probable human carcinogen.
    2.    Phenol in phenol-formaldehyde resin is highly toxic by skin absorption and inhalation, and can severely burn skin.
    3.    If these resins are improperly cured and contain residual formaldehyde, they may cause irritation and allergic reactions. Trace amounts of free formaldehyde may cause allergic reactions in people who are already sensitized to it.
    4.    Machining, sanding, or excessive heating of the cured resins can cause decomposition releasing formaldehyde, carbon monoxide, hydrogen cyanide (with amino resins) and phenol (with phenol-formaldehyde resins).
    1.    Avoid using formaldehyde resin systems.
    2.    Wear gloves when handling amino and phenolic resins.  Follow instructions carefully for proper curing.
    3.    Local exhaust ventilation is necessary if handling the cured resin involves heating and/or decomposition.
    4.    People who have become sensitized to formaldehyde will probably have to avoid these resins.

Epoxy Resins

Epoxy resins are used for casting, laminating, and molding, and as adhesives.  When mixed with stone or metal dusts, they resemble actual stone or metal.  Epoxy resins consist of two components: the epoxy resin; and hardeners, which are often amines.  Mixing gives off heat which can vaporize solvents and other components.

    1.    Epoxy resins are moderately toxic skin and respiratory irritants and sensitizers.  Resins containing diglycidyl ethers are probable human carcinogens, skin and eye irritants, and may damage the bone marrow.
    2.    Amine hardeners are moderately toxic by skin contact and highly toxic by inhalation.  They are potent skin sensitizers and irritants, causing dermatitis in almost 50% of workers regularly exposed to them.  They also can cause asthma, coughing, bronchospasm, and other respiratory difficulties. 
Other hardeners are also toxic.
    3.    Epoxy resins contain solvents of varying toxicity. 

    1.    Wear goggles and gloves when using epoxy resins.
    2.    Use with local exhaust ventilation, or work at a bench against a window with a window exhaust fan.  If ventilation is not adequate, wear a NIOSH-approved respirator with organic vapor cartridges for large amounts.
    3.    If the epoxy system contains flammable solvents, follow careful safety procedures for fire prevention (see our data sheet on Fire Prevention for more information).
[Occupational contact dermatitis due to epoxy products frequently involves the exposed parts of the body, with the typical clinical features of an airborne contact dermatitis.  Epoxy resins are in fact included in both the list of irritant and allergic contactants.  We report here 7 cases of airborne occupational contact dermatitis due to epoxy products.

(Artists working with epoxy resins and glues must not only avoid skin contact, but should have good ventilation in order to prevent airborne contact with the epoxy vapors.  - Ed.)]

Polyester Resin

Polyester resins are used for laminating, molding, and casting.  For molding and laminating, fiberglass is the most commonly used reinforcement.  In most polyester resins, styrene is used as the cross-linker; other cross-linkers include methyl methacrylate, vinyl toluene, and alpha-methyl styrene.  Ketone solvents are sometimes included.  Methyl ethyl ketone peroxide is the commonest hardener, although benzoyl peroxide and cumene hydroperoxide are also sometimes used.  Promoters or accelerators used with polyester resin include cobalt naphthenate and dimethylaniline.

    1.    Styrene is moderately toxic by skin contact and highly toxic by inhalation.  It is absorbed through the skin.  Styrene is a probable human carcinogen, a potent narcotic, and a respiratory and eye irritant, causing coughing and burning of the eyes and nose.  Styrene can also possibly damage the liver and nervous system.  While it has good initial odor-warning properties, olfactory fatigue may set in.  Vinyl toluene and alpha-methyl styrene have similar toxicity to styrene.  Methyl methacrylate is discussed above.
    2.    Cobalt naphthenate is moderately toxic by skin contact and inhalation, and possibly causes allergies.
    3.    Dimethylaniline is highly toxic by skin absorption and inhalation causing methemoglobinemia (in which the hemoglobin in the red blood cells is converted into a form which will not release oxygen), resulting in cyanosis.  Primary symptoms are a bluish discoloration of the lips, ears, and nail beds, and then headaches, weakness, and oxygen starvation.

    4.    The hazards of peroxide catalysts are discussed below.
    5.    Fiberglass is a skin and respiratory irritant.  Inhalation of fiberglass dust created by cutting fiberglass or sanding the cured fiberglass-containing polyester can cause irritation and other respiratory problems.  The classification of fiberglass is  "reasonably anticipated to be a carcinogen," by the U.S. Department of Health and Human Services, and "possibly carcinogenic" to humans by the International Agency for Research on Cancer (IARC).
    6.    Styrene, vinyl toluene, a-methyl styrene, and cleaning solvents such as methyl ethyl ketone are flammable.  Acetone is extremely flammable.

    1.    Wear gloves and protective goggles when pouring and handling polyester resins.
    2.    Use in a local exhaust hood or use a window exhaust fan with a NIOSH-approved organic vapor respirator.  Large scale polyester resin use should be done in a large spray booth or while wearing a supplied-air respirator.
    3.    Clean up any spills immediately.  Cover the work area with disposable paper towels or newspapers.
    4.    Do not use styrene for clean-up; instead, use acetone.
    5.    Wear clothing that covers the arms and legs and remove immediately after work; then shower.
    6.    Wear a NIOSH-approved toxic dust respirator when cutting fiberglass or sanding the cured sculpture.  If the sculpture is not completely cured, wear organic vapor cartridges as well.
    7.    Cover exposed skin (neck, face) with a protective barrier cream.
    8.    Wear heavy neoprene rubber when handling dimethylaniline accelerator.  Be very careful not to spill it on clothing since it can permeate through the material.
    9.    Store flammable solvents safely.  Do not use solvents or resin near an open flame or lit cigarette.  Store solvent or resin-soaked rags or paper in an approved self-closing waste disposal can which is emptied every day.
    10.    See below for information on organic peroxides.


Polyurethane Resins

Polyurethane resins can be used to make elastomers (e.g. coatings and molds), adhesives, and rigid or flexible foams. They are usually two-component systems, consisting of Part A - the polyol, and Part B - the isocyanates used to cross-link the polyol.  The polyol also contains such as metal salts or amine catalysts.  Foaming systems also contain blowing agents, often fluorocarbons (e.g., freons).
Polyurethane elastomer resins can be one or two component systems.  The one-component systems are air or moisture cured. Most household urethane varnishes and paints do not contain isocyanates, but are the finished polyurethane dissolved in solvents, which dry by evaporation.

    1.    Isocyanates are extremely toxic by inhalation, causing bronchitis, bronchospasm, chemical pneumonia, and severe acute and chronic asthma at very low concentrations, even in people without a prior history of allergies.  They also cause severe eye irritation.  Methyl isocyanate was the chemical that killed over 2500 people in Bhopal, India when released into the atmosphere several years ago. 
The degree of hazard depends on the volatility of the diisocyanate and its physical form.  TDI (toluene diisocyanate) is the most volatile and the most hazardous.  MDI (diphenyl methane diisocyanate) is less volatile and, less hazardous than TDI.  Polymeric isocyanates usually contain about 50% MDI.  If heated or sprayed, any isocyanate is extremely hazardous.  Note that isocyanates cannot be detected by odor until the concentration is many times higher than recommended levels.

    2.    Amines used as catalysts are moderately toxic by skin or eye contact or inhalation since they are sensitizers and irritants.
They may cause allergies.
    3.    Organotin compounds used as catalysts are highly toxic by skin absorption, damaging the liver and nervous system.  They may also cause skin allergies and irritation.
    4.    Fluorocarbon blowing agents used for foaming are slightly toxic by inhalation.  They can cause narcosis at high concentrations, changes in the heart rhythm (arrhythmia), and even cardiac arrest at very high concentrations.

    5.    One-component polyurethane systems using precapped isocyanate polymers are less hazardous than the two-component systems due to low volatility, unless they are sprayed.
    6.    Dust from sanding and cutting finished polyurethane may cause skin and respiratory problems due to the presence of unreacted chemicals from the curing process.
    7.    Heating polyurethane is highly hazardous, since decomposition products include carbon monoxide, nitrogen oxides, acrolein, and hydrogen cyanide, all of which are highly or extremely toxic by inhalation.

    1.    Do not work with polyurethane resins if you have any history of allergies, asthma or other respiratory problems.
    2.    Do not spray polyurethane resins unless it is done inside a spray booth or you wear a supplied-air respirator (e.g. self- contained breathing apparatus).
    3.    Mix polyurethane resins in a local exhaust hood, or wear a NIOSH-approved full face gas mask with organic vapor canister or air-supplied respirator.  Use an exhaust fan to remove the vapors from the room.
    4.    Wear gloves and goggles when handling these resins.
    5.    When sawing, sanding, or otherwise fabricating polyurethane, wear a NIOSH-approved respirator with organic vapor cartridges and toxic dusts and mists prefilters.


Silicones and Natural Rubbers

Silicones and natural rubber can be used as sealants, adhesives, molds, and mold releases.  There are two basic types of silicone resins: single-component systems that are cured by atmospheric moisture; and two-component systems that are cured by peroxides.  These can contain solvents such as acetone or methylene chloride.  Water-based natural rubber latex can also be used to make molds.  Other compounds include rubber or contact cements containing rubber dissolved in solvents such as hexane, naphtha, and 1,1,1-trichloroethane.  Rubber cements and latex rubber dry by evaporation.

    1.    Single-component silicones (including spray types) release acetic acid or methanol into the air.  The acetic acid is irritating to the eyes and respiratory system.  Methanol is a nervous system poison and is moderately toxic by inhalation.
    2.    The silicone resin in two-component systems is moderately toxic and irritating by skin contact.
    3.    See below for the hazards of peroxides.
    4.    Natural rubber latexes contain skin-irritating chemicals, and can cause severe allergic reactions in some people.
    5.    n-Hexane, found in some rubber cements and contact adhesives, is extremely flammable, and can cause peripheral nervous system damage chronic inhalation.
    6.    Methylene chloride is highly toxic by inhalation.  It may cause narcosis and changes in heart rhythm (arrhythmia).  It is also converted into carbon monoxide in the body.  Smokers and people with heart problems are at higher risk.
    7.    1,1,1-Trichloroethane is moderately toxic by inhalation, and can cause death at very high concentrations (e.g. in enclosed spaces).

    1.    Substitute water-based or heptane-based rubber cements and contact adhesives.
    2.    Use rubber cements containing hexane with good ventilation to prevent build-up of vapors.  Do not allow smoking or open flames when hexane or acetone is present.  Store large amounts (greater than one pint) in approved safety containers.
    3.    People with heart problems should not use methylene chloride-containing products.
    4.    Wear gloves and goggles when handling silicone resins, rubber latex or solvents.
    5.    See the section on organic peroxides.

Organic Peroxides

Organic peroxides are commonly used as hardeners or catalysts (more accurately initiators) for curing polyester, acrylic, and some types of silicone resins.  Common peroxides used are benzoyl peroxide, methyl ethyl ketone peroxide (not to be confused with the solvent methyl ethyl ketone), and cumene hydroperoxide.  Usually these peroxides come as liquids or pastes dissolved in materials like dimethyl phthalate.

    1.    All organic peroxides are highly flammable and often explosive.  Benzoyl peroxide becomes a shock-sensitive explosive above 120F (49C) and explodes above 176F (80 C). Methyl ethyl ketone peroxide (MEK peroxide) can decompose by sunlight and explodes above 230F (110C); it is extremely shock sensitive.  These peroxides can also decompose explosively when mixed with mineral acids, plastic resin accelerators, and many combustibles.  MEK peroxide forms an explosive mixture with acetone.
    2.    Methyl ethyl ketone peroxide can cause blindness if splashed in the eyes. Cumene hydroperoxide is moderately toxic by skin and eye contact and may have cumulative effects.  It may also cause allergies.  Benzoyl peroxide is only slightly toxic by skin contact, and somewhat more toxic by eye contact.

    1.    Store peroxides separately from other combustible materials, and keep in original (never glass) containers.
    2.    Do not store large amounts of organic peroxides, or keep them for long periods of time.
    3.    Never dilute peroxides with other materials.  Never add accelerators to peroxides, or acetone to MEK peroxide.
    4.    Do not heat peroxides.
    5.    Use disposable paper cups and wooden sticks for mixing small amounts of resin and peroxide.  Otherwise use polyethylene, glass, or stainless steel containers.
    6.    Soak all tools and containers in water before disposal.
    7.    Clean up spills immediately by soaking up the peroxide with vermiculite if in liquid form, or with wet vermiculite if in powder or paste form.  Do not sweep since this has been known to start fires.  Use nonsparking tools to clean up.
    8.    Do not discard unused peroxide or peroxide/vermiculite mixtures; this can cause a fire or explosion.  Peroxides can be disposed of by reacting with the plastic resin or by carefully reacting with a 10% sodium hydroxide solution.

                                                                                        plastics (Wikipedia image)

Finished Plastics

Plastic sheets, blocks, and film can be fabricated by cutting, drilling, carving, sawing, heating, vacuum forming, and many  other methods which use physical tools or processes.

Examples of plastics which can be treated in this way include acrylic (lucite, Plexiglas), polyvinyl chloride, polystyrene, polyethylene, and polypropylene.  Foamed plastics (e.g. polystyrene and polyurethane) can also be sawed, sanded, and heated to form it into various shapes.  Some plastics, such as polystyrene, polyvinyl acetate, and polyvinyl chloride, are available as molding pellets which can be heated in a mold.

Plastics can be glued with solvent cements or other adhesives.

    1.    Some polymer dusts may cause irritation or allergies if inhaled due to the presence of an unreacted monomer of other additives.  Examples are phenolic and amino plastics, acrylic powder, and polyurethane dusts.
    2.    Heat decomposition of finished plastics can result from processes such as hot wire cutting, electric sanding, drilling, and sawing, producing highly toxic gases such as carbon monoxide, monomers, nitrogen oxides and hydrogen cyanide.

    3.    Heating acrylic plastic results in decomposition to the monomer methyl methacrylate, a respiratory irritant, sensitizer and narcotic (see the section on Acrylic Resins).
    4.    Heat decomposition of polyvinyl chloride (PVC) occurs above about 400F (205C), releasing highly toxic hydrogen chloride gas.  Exposure can cause "meatwrappers asthma", a disease noted among meatwrappers who hot wire PVC film.

    5.    Heat decomposition of foamed polystyrene (styrofoam) or polyurethane can release a large variety of highly toxic gases including nitrogen oxides, hydrogen cyanide, carbon monoxide, and monomers (e.g., styrene).
    6.    Heating polyfluorocarbons can cause polymer fume fever, a disease similar to metal fume fever, with symptoms of nausea, chills, fever, headaches, coughing, and shortness of breath. This is often caused by smoking a cigarette in the presence of fluorocarbon dust.  The cigarette's heat is high enough to decompose the fluorocarbon.

    7.    Many of the solvents used to cement plastics are highly toxic.  Acrylic cements in particular commonly contain chlorinated hydrocarbons such as ethylene dichloride or methylene chloride.  Both are probable human carcinogens and narcotics, especially ethylene dichloride, which can also cause liver and kidney damage.  Methylene chloride is converted into carbon monoxide in the body and can cause heart arrhythmias. This is especially hazardous for smokers and people with heart problems.

    1.    Have good general ventilation or local exhaust ventilation when fabricating plastics.  Use water-cooled or air-cooled tools to keep decomposition of the plastic to a minimum. In heat fabrication processes, use the lowest temperature possible to avoid decomposition of the plastic.
    2.    You may need an organic vapor respirator to work safely with acrylic plastics if you do not have adequate ventilation.  Use a NIOSH-approved respirator with combination organic vapor/acid gas cartridges with PVC.
    3.    Sanders, saws, and other electric tools that generate a lot of dust should be equipped with dust-collectors.
    4.    Clean up by vacuuming or wet mopping; not sweeping.
    5.    Wear gloves and goggles when handling solvent cements.  Use as low toxicity a solvent as possible, for example, acetone instead of chlorinated solvents.


Plastics Additives

Additives used with plastics and their resins include plasticizers, stabilizers (e.g., ultraviolet absorbers andantioxidants), colorants (dyes and pigments), fillers (e.g., talc, quartz, clay, fused silica), reinforcements (e.g., fiberglass), fire retardants, inhibitors, accelerators, and solvents. Inhibitors and plasticizers may be already in the resin or added later.

Hazards and Precautions
These additives are discussed in other CSA data sheets: mineral additives, and phthalate plasticizers - "Traditional Sculpture;" pigments - "Art Painting and Drawing;" and dyes - "Dyeing Safely."
Many organic phosphate esters can be absorbed through the skin, and inhalation or ingestion may cause central nervous system damage, possibly leading to paralysis, convulsions or anesthetic effects.  Some act like mild nerve gases, and are skin, eye, and respiratory system irritants.  Examples are tributyl phosphate, tri-para-cresyl phosphate, and the most toxic tri-orthocresyl phosphate (TOCP), which should be avoided.

* This data sheet was adapted from chapter 16 of Artist Beware by Michael McCann.

Art Hazard News, Volume 18, No. 4, 1995

Epoxy Resin and Dermatitis Insert: Art Hazard News, Volume 12, No. 1, 1989

This article was originally printed for Art Hazard News, copyright Center for Safety in the Arts 1989 and 1995. It appears on nontoxicprint courtesy of the Health in the Arts Program, University of Illinois at Chicago, who have curated a collection of these articles from their archive which are still relevant to artists today.