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Acrylic Resist Etching             
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Plastics  (Health in The Arts)



Eduardo Paolozzi, 1996,
experimental artwork
for
acrylic resist etching
projects (middle)


by Friedhard Kiekeben, 1994-2019


Many Media in One: Acrylic paint products today
dominate the world of artist paints,
and have over the years also been
adopted for many other applications
in silkscreen printing, etching, collagraph printing,
and are also found in glues, mediums, binders,
home decorating paints, craft products, and more.


The polymer-forming, 'water-based', paints
contained in tubs, bottles and tubes
are almost universally thought of
and advertised as a safe,

and exceedingly useful technique and material...

yet few of us know what is actually in the mix;
most brands and their formulae are patented
and ingredient lists are often hard to obtain.


In the following we will shed some light on the matter, and try to convey an understanding of why acrylics should be regarded as powerfully reactive and potentially damaging chemicals, while being the useful, colorful, versatile, and essential buttery substance in much of professional art making that so many artists have come to rely on, across many media.







Acrylic Resist Etching: An Introduction

Many artists are familiar with acrylic painting, but what is Acrylic Resist Etching? 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, and often acrylics are used to achieve desired effects.


Through the introduction of acrylic paint, varnishes  and mediums into the process, printmaking has obtained a new affinity with the materials of painting. In the following we will discuss both topics of contemporary printmaking, and of acrylic paints and mediums in tandem, and anyone interested in either the new forms of printing, or in painting with acrylic paints, will gain insights into usage, chemistry, and safety of these now connected forms and mediums.


In the more mechanical or dry intaglio 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 using acrylics, 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:






Acrylic paint seen with an
electron microscope









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

Groce/Kiekeben/Greenwood






Methyl methacrylate is a reactive resin found in most acrylics |
use only de-ionized water to dilute acrylics
to ensure full polymerization, and use good ventilation;
the highly reactive MMA is not considered 'nontoxic'.








A Painterly Aesthetic
in Intaglio Printmaking


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





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


Properties of Acrylics used in Etching


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










sdd;l;l;ll
Richard Hamwi: Chime, 1983, (Spandorfer)
watercolor and collage.
"I use acrylic medium and adhesive because it is
nontoxic and has long-lasting conservation properties."

PVA glue, (polyvinyl acetate), was invented
in 1912 by a German chemist,
and is one of the oldest and most widely used polymer
binders. It is both archival and normally safe to use.

PVA emulsions are synthesized from vinyl actetate monomer, which is toxic.

Cheap PVA glues or mediums may possibly be contaminated with residual VA.









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.
















Vincent Finazzo, Delineation I, aluminum etching,  2008


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     
 
See    ETCHING INGREDIENTS


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 (Polymetaal) 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/Pledge floor finish (SC Johnson's Wax Klear or Klar/Klir 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. 




image: Acrylic Paint Review 


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.








        METHOD
      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


        METHOD

      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
Aquatint







Safer Stripping with Orange Zest Solvents - sample

An acrylic hard ground can be stripped off in a strong soda ash solution (1 part crystals to 3 parts warm water). Or use a citrus-based safe solvents now on the market (such as 'D*Solve', 'CitraSolv', or 'De-Solv-it') many of which can remove acrylics, etching grounds and hardened ink and paint.

'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.' 



There is a growing number of such citrus-based solvents on the market. The key ingredient, D-Limonene, also known as orange oil, the safe and innovative solvent extracted from orange peel, can be purchased directly from the citrus industry. For example, see www.citrusdepot.net. This solvent is more powerful than mineral spirits, strong enough to dissolve hardened acrylics, oil paint, printing ink, (and even some plastics) with ease, yet medical studies have found no carcinogenic or neurotoxin hazards comparable to the petrochemical solvents. Users should, nevertheless, still handle the solvent with care: ensure good ventilation/use vapor mask and take fire precautions when using the new orange oil solvents. Unlike oil-based products, orange oil is considered biodegradable. 

Some big brand 'orange' or 'citrus' solvents are mixed with traditional solvents, such as Naphtha or Glycol Ether, and cannot be considered a 'safer alternative'. 

For more information click on our Safe Solvents page


IMPORTANT:  ALL LIQUID, VOLATILE, HYDROCARBON-BASED
SOLVENTS REQUIRE SOME FORM OF RESPIRATORY PROTECTION
(this includes both petroleum products, but also bio-based solvents,
such as ethyl alcolhol, soy/ethyl/methyl lactate, orange oil,
and many others)


below, a recent, 'eco-friendly' product, Eco-Solve,

made for artist use:   'NaturalEarthPaint' 

(https://www.naturalearthpaint.com)

"Does not irritate the skin
Does not emit harmful vapors.
Soy-based" (company quote).


       


METHOD
      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










     Safe Painting Guide                                                       







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

                                    






Jackson Pollock in his studio, Hans Namuth Estate
















(from: A pilot study to evaluate VOCs outgassed in polymer filaments, Shari Cheves, 2014)

Inherent Instability in Monomers and Polymers

"Plastic polymers are created from monomers almost exclusively derived from crude oil with far-reaching impacts on the health of humans and the environment. These highly reactive monomers form stable bonds in polymers through polymerization, though the chemical reactions are never quite complete. This inherent instability contributes to the release of residual monomers, plasticizers, ame retardants, solvents, and other additives as polymers degrade.

Based on the toxicity of monomers, research has defined the most hazardous polymer families as polyurethanes, polyacrylonitriles, polyvinyl chloride, epoxy resins, and styrenic copolymers. Monomers and other by-products are released through various modes of degradation such as heat. Nitrogen-containing plastics such as nylon and polyurethanes typically release hydrogen cyanide; chlorine-containing materials such as polyvinyl chloride typically release hydrogen chloride; and polystyrene, polyesters such as polycarbonate, nylons, and polyurethanes may be more likely to degrade into their original monomers."






________________________________________________________________________________________________

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  (Health in The Arts)



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. 




                                                                                        plastics (Wikipedia image)






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.



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