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Acrylic Aquatint in the 1990s
Early beginnings

an overview 
from early acrylic resist etching research,
F. Kiekeben, 1994-98

During the 1980s some UK print shops started using spray paint to facilitate larger aquatint projects in etching. 

In the early 1990s Keith Howard refined and perfected the method, now using special acrylic mediums (such as Speedball screen filler) and an airbrush compressor.




. Aquatint
     Aquatint in acrylic resist etching
     Creating a uniform aquatint
     Creating a modulated aquatint
     Scraped aquatint
     Aquatint and spit bite
     Printing an aquatint plate

Intaglio techniques often appeal more to artists with an interest in line and texture than to those seeking more painterly effects. In fact, intaglio printmaking is ideally suited for realising tonal and painterly possibilities.

The most versatile way of creating tonal areas in an etching is by means of a technique known as AQUATINT. Opinions vary as to where the term originates but a plausible explanation is that the term was derived from aqua fortis (to etch with strong acid) and tinta (tones made by etching). In aquatint, tonal effects similar to those resulting from strokes or washes of pigment in painting are achieved by the corrosive bath. The technique of spit biting even allows the artist to paint with the etch itself.

Aquatint involves the application of an etch resistant dot structure to the metal plate which is then immersed in a mordant. According to the length of bite this creates areas of a varying depth and roughness on the surface which are capable of holding ink deposits which result in printed tones that range from the faintest grey to the blackest black. If aquatint is applied in color etching it can produce a broad range of hues.




a spray aquatint etching made at Edinburgh Printmakers in the early 1990s.


 https://www.edinburghprintmakers.co.uk




With most etch techniques only those marks incised into the plate create the intaglio whilst the largest portion of the metal remains intact as the surface of the plate. The opposite is the case with aquatint. Here the majority of the metal is removed, only the etch resistant dots remain on the surface like little islands in an eroded landscape. When working with aquatint it can be useful to have a different mental approach than to say line etching. Rather than thinking in terms of making direct black marks on a white background, the imagined background is potentially darkly tonal and it is the artist's task to shape lighter areas from it. The image is created by painting with stop-out varnish or by any other etch resistant means such as adhesive tape, litho crayon etc.

If an aquatint grain is applied to the plate as an overall layer, any areas that are stopped out before the immersion in the etch will produce white marks surrounded by a dark tone. Any marks painted on after subsequent immersions will reflect the depth of bite and the respective grey tone at that time - for example, a mark made after a 5 minute etch will print as a medium grey.

A tremendous spectrum of light and tone can be created when aquatint is used in this way of negative mark making.

If the aquatint is etched in stages one should not forget that biting times must always be added up. An aquatint plate that has already been etched for 10 minutes and is then, after stopping-out, placed back in the mordant for another 20 minutes has received an overall etch of 30 minutes. So all non protected areas of metal will bear the dark tone of the 30 minute bite whilst the stopped-out ones will bear the grey tone of a 10 minute bite; and if some areas were stopped-out before any biting, these would print as the white of a non-etched area.

The appearance of an aquatint is not only determined by biting times but also by the size and density of the dots applied to the plate. A modulated aquatint consisting of dots of varying density can cover the whole tonal spectrum with only one immersion in the mordant. This is a major advantage of aquatint over the traditional rosin method which was mainly limited to flat and even tones achieved by numerous biting and drawing stages.

Some artists prefer to use the tonal and painterly properties of aquatint in a much more direct way, where the mark you make is the mark you get. The way to achieve this is by use of the lift process. If for example the artist wanted an etching to be composed of bold and delicate black brush strokes, he would simply apply those on the prepared plate by means of a lift medium. This is then covered with etchant resist and after drying, the lift medium is removed, thus revealing the metal where a mark was made. Now an aquatint grain is applied to this area, the plate is etched, and the resulting print will bear the positive brush marks that were applied to the plate at the beginning of the process.

Aquatint is ideal in combination with other etch techniques as it allows linear and textural elements to be fused with tonal areas. The aquatint does not have to be the first step on the plate, it can just as easily be added later to plates that have already been worked on with a hard ground, with open bite, or with other etch techniques. Also, it is not necessary to cover a whole plate with the aquatint dots as these can be applied to a confined area of exposed metal too. As with all repeated biting, it is important to make sure that the plate is free from grease or loose residues before the aquatint is applied to the plate.


Aquatint in acrylic resist etching
In the acrylic based etching system, the etch resistant dot structure is applied by spraying acrylic varnish onto the plate. A sprayed aquatint offers great versatility; the dot structure can be applied as a perfectly even layer of any required density, or the spraying devise can function as an air-brush, to create lines, blends, cloudy effects etc. On a more improvisational level, a serviceable aquatint can be achieved by using an acrylic aerosol. There are numerous products on the market that would be suitable as a resist. For more professional workshops, an electric compressor with spray gun, preferably used in an enclosed and ventilated spray area or booth, serves as an aquatinting facility. A spray-painting compressor with gravity fed gun is ideal for laying even aquatints whilst designer airbrush equipment is better suited to modulated work. Any workshop wishing to take full advantage of the safe aquatint techniques would be advised to have both these pieces of equipment in operation.

There are a variety of good acrylic sprays for aquatint. Most of these are made up by adding a dark dye or pigment (e.g. Koh-i-Noor black ink) to a binder (e.g. Golden GAC 200, Future or Lascaux 2060) for better visibility. Acrylic spray ink works on any kind of metal, proves to be outstandingly etch resistant and does not run during application. Diluted Speedball screen filler is Keith Howard's favoured spray ink. This ground breaks up gradually during biting, so the aquatint dot gradually shrinks during biting. Very dense and velvety tones and blacks can be achieved this way. Keith Howard also developed another product - the Badger airbrush aquatint solution - which performs well on all metals and has excellent visibility during application due to its strong black pigmentation.


Creating a uniform aquatint

        MATERIALS                                                                                        
        Products and equipment needed for a uniform aquatint:
  • prepared metal plate
  • compressor and spray gun + airbrush set up in spraying facility
  • spray mask
  • newsprint
  • jug filled with detergent water
  • Acrylic airbrush solution
  • de-ionised water


        METHOD                                                                                             

        Mix a self-made aquatint as follows:

  1. Add a small amount of pigmented ink (ideally Koh-i-Noor black ink) to the varnish, stirring continuously until the mix looks sufficiently opaque.
  2. Do not add too much ink as this may affect etch resistance.
  3. Both Lascaux varnish and Hunt Speedball need diluting before they can be used in a spray gun. Add between 15-20% de-ionised water (pre-boiled water will do just as well) to the varnish or Speedball based aquatint ink. Start with a small amount and stir continuously whilst gradually adding more water. A more dilute solution will produce a slightly finer spray mist but is more likely to run.


Even though the acrylic spray inks are waterbased it is not advisable to expose yourself to any sprayed substances; so put on a spray mask and ensure adequate ventilation of the spray booth.

Familiarise yourself with how your spray equipment works and practice spraying on a test piece.



        Apply a uniform aquatint spray as follows
  1. Gently shake the spray ink before you fill the ink container of the spray gun.
  2. Position the plate in an upright position at arms length. Use a sheet of newsprint as a background on which to observe and control the spray deposit. The spray will be barely visible on the plate itself.
  3. Switch on the compressor and test the spray on the newsprint, well away from the plate. The density of the aquatint grain is determined both by how much compressed air is added to the ink (this is controlled by a screw on the spray gun) as well as by how far away you are from the plate. A good distance between plate and gun is between 1-2 ft; a closer range produces finer spray particles but you are more likely to over spray the plate. The aim is to produce a FINE MIST on the plate rather than total coverage. If areas are over sprayed there will not be enough exposed metal for the etch to work properly - and therefore no tone will be produced!
  4. Once you have adjusted your set up to a fine mist you can start spraying onto the plate by passing over it in regular parallel sweeps, gradually moving from the top of the plate to the bottom. Make sure to change direction outside the plate boundaries.
  5. A single layer usually suffices on copper and zinc plates.
  6. Steel plates should only be sprayed with the varnish mix and work best with a second layer of mist, this time in the opposite direction. Allow a couple of minutes drying between applications.
  7. Aquatint plates dry within 20-40 minutes and benefit from being kept in a drying facility prior to etching.
  8. The spray gun is quickly cleaned by first running detergent water through it for 30 seconds and then by rinsing it in clean water. If the gun becomes clogged with hardening acrylics, its detachable components should be soaked in a concentrated solution of soda crystals and then cleaned with a brush and tooth pick.
Remember:
The finest aquatints are achieved by adjusting the gun to a very fine spray (higher air to ink ratio) of more dilute spray ink and by applying this in several layers.
Thicker aquatint granules (useful for deep etches) are produced by adjusting the gun to its most powerful spray setting; by using a more concentrated spray ink; and by increasing the distance between plate and gun.

Quick Pressure Guide:
Strong Pressure        (50-80 psi)             =     fine dots
Weaker Pressure      (below 30 psi)       =     coarse dots



Creating a modulated aquatint
The process of applying a modulated aquatint does not differ greatly from that of applying a uniform one, described previously. However, with this technique the artist is not aiming to use the spray equipment in an even way but to use it as a creative tool with which to create modulated areas of differing density on the plate. The spray gun can be used to render larger aquatint clouds but a designer airbrush is a more appropriate tool as it offers much greater versatility.

Modulated aquatint can be used imaginatively to create spatial effects in abstract compositions, to conjure up clouds in a landscape; to describe the volume of three-dimensional objects; and for many other purposes where a tonal range or a blend is required. In true printmaking style, this process is characterised by the fact that the densest marks sprayed onto the plate actually represent the lightest areas on the print, while the open ones applied as a fine mist produce the darkest areas of the composition. Areas on the plate that are not touched by any sprayed marks or gestures will of course etch as open bite. If this is to be avoided it might be advisable to start off by layering a faint overall mist on the plate before the main component is sprayed. After drying a modulated aquatint can be stopped-out as usual and even though a single layer of modulated aquatint can already encompass the whole tonal spectrum, etching in stages is another possibility to enhance the illusionistic depth characteristic of this method.

Other creative possibilities with airbrushing include the use of masks and stencils to produce sharp outlines and, of course, using the brush itself to spray clearly defined shapes and lines etc.


Scraped aquatint
Aquatint not only has a similar name but also has a similar appearance to the mechanical technique of mezzotint which is also used to produce tone on the plate. Where the techniques differ is that aquatint creates an etched dot structure while mezzotint produces a mesh of burrs. Both invite the artist to make use of tools such as scrapers, burnishers and steel wool to work soft tones, marks, blends and light areas into the roughened surface. An aquatint that is scraped and burnished will seamlessly blend in with other features of the composition and an aquatint lightened with steel wool can reveal underlying intaglio marks that seemed to have vanished in the etch process.

The rich quality of mezzotint is often viewed as superior to the blacks that can be achieved more quickly using aquatint. This is probably due to the granular structure of the aquatint which tends to be present even when the aquatinted mark has been eroded so deeply as to print as black. As with etching in general the aquatint will become much richer if used in a multi dimensional way. A truly dense black, without any remaining white specs, can be achieved from an aquatint that is applied and etched twice. Start by applying a coarse grain and etch to a fair depth before applying a finer grain and etching a second time. The dot layers will lock into each other to produce a complex terraced effect, producing a tone that is more saturated than the more uniform aquatint. A more direct way of deepening an aquatint that has already been etched is to rub the roughened metal surface with a soft litho or wax crayon; small etch resistant particles will adhere to the plate and act as a localised coarse aquatint and when re-etched, the result is a lively coarse grain black.

Aquatinted areas can be more vulnerable than other kinds of intaglio after application, during etching and at the printing stage. Some wear may show in larger editions. Aquatints on the relatively soft zinc are particularly sensitive, while on copper it is much more durable and can be hardened for large editions by steel-facing the plate. Copper is also the best choice for very fine aquatints and for etchings where the broadest tonal range is required. As mentioned previously, steel can produce a tonal quality all by itself, but again, the use of aquatint will enhance this natural tonality.

The length of time that an aquatinted plate is etched is crucial to the final result - more so than with other techniques. In a well-activated bath of ferric, just a couple of minutes can make the difference between the required tone and an over etched plate. Due to the changeable nature of the corrosive solution it is recommended that  the artist determine typical biting times for an aquatint by making an etching step test before an important plate is etched. Aquatints can be easily over bitten which typically results in a shallow rather than a dark tone because the dots have been completely eroded.

Aquatint plates should not be exposed to excessive oxygenation or agitation in ferric tanks as this may cause damage to the fine grain. Ideally copper and brass plates should be dipped in a de-oxidising solution before and after etching; this is a simple salt, water and vinegar mixture that can quickly remove any tarnishing.

Aquatinted copper and zinc plates etch well in trays but must be rocked during etching to remove sediment. Aquatint plates should not, however, be etched face down as the bottom of the tray may scratch the aquatint.


Aquatint and spit bite
There is an aquatint technique that does not involve the immersion of the plate in a corrosive bath. In spit bite, which is sometimes more precisely described as creeping bite, an aquatint grain is etched directly into the plate by painting the mordant onto it. Flowing tones of the most delicate kind can be produced in this way - the intaglio equivalent of a watercolor wash.



        MATERIALS                                                                                        
        Products and equipment needed for spit bite:
  • aquatinted copper plate
  • jar of full strength ferric chloride or Edinburgh Etch 45 Be
  • tray larger than the plate
  • strong acid resistant gloves
  • goggles
  • brushes of various sizes
  • etching and rinsing space in allocated area


        METHOD                                                                                             

        Apply spit bite as follows:
  1. Place a very finely aquatinted copper plate in the tray.
  2. Make marks by painting the metal salt solution onto localised areas.
  3. The longer the ferric stays in one place the darker the etched tone will be.
  4. Sharp edges can be avoided by brushing water around the etched areas to dilute the strength of the ferric.
  5. To control the depth of bite the plate can be intermittently rinsed and inspected before more solution is brushed on.
  6. If the brushed marks are meant to be more defined, a drop of detergent can be added.

A spit bite usually etches quite quickly and dark tones can result from this fine but shallow etch within minutes.

No gases are produced by the ferric when used on copper or brass, but skin contact should be avoided.

Spit biting can also be executed very successfully on zinc plates using saline sulfate solution.



Printing an aquatint plate
Etched plates with aquatinted areas should be printed with moderate pressure - especially when copper and zinc plates have been used or a plate has not been steel faced. Repeated printing is likely to flatten the delicate aquatint. The tonal quality of aquatint comes out best on a print if a good amount of plate tone is used. A plate wiped predominantly with scrim or by hand tends to have these softer tones whereas a plate heavily polished with tissue paper will result in a print that shows more of the dottiness of the aquatint - something resembling stars twinkling in the night sky. The tonal values of an aquatint can also be enhanced by adding more light copperplate oil to the ink than usual, and, if the plate is printed black, by using a specialised ink such as the very rich Charbonnel Black No. 55985.