Mark Making Techniques
The Chemistry of Acrylics
Stop-out varnish
Direct Stop-out marks and open bite
Stop-out: an essential aidThe Chemistry of Acrylics
All grounds used in acrylic resist etching consist of complex acrylic polymer substances that are in a more or less liquid form and contain water as a solvent. They acquire the properties that make them ideal for intaglio printmaking during the drying process. The separate acrylic particles that form a watery emulsion of monomers in the liquid state start to bond with each other as the water evaporates. Polymerisation is complete when these monomers remain firmly linked as long polymer chains, thus creating a very tough plastic-like substance that is both hard wearing as well as perfectly etch resistant. Acrylics brushed, poured, rolled or sprayed onto a prepared plate ultimately form a strong bond with the metal surface. During etching, acrylics do not tend to chip off along the edges of the eroded intaglio and, if required, can even be left on plates during printing. As long as they are in the liquid state, acrylic grounds can be easily cleaned from brushes or work surfaces with soapy water, but become water-resistant once they have fully hardened.
The blending together of the components that make up a self-mixed acrylic ground has to be carried out slowly and with care to make sure that an emulsifying process takes place. Small quantities should be added gradually while stirring continuously. Any water (de-ionised) has to be introduced to the mix in this same gradual manner, and grounds should only be diluted if instructed. Acrylic grounds left unused for a period of time need some stirring or shaking to re-emulsify the mixture. Many acrylic grounds dry very quickly and drying times as well as bonding properties are enhanced still further by using a hot drying cupboard.
It is often believed that plastics are hard to break or dissolve but the acrylics used in this manner of printmaking are easily broken down and removed by alkaline substances. This is essential for reclaiming plates after etching. The chemical process performing this miracle is known as saponification. In layman’s terms it means that the alkaline stripping process turns the tough acrylic substances into a harmless soap-like solution.
Stop-out varnish
Stop-out varnish is often considered a product to be used in conjunction with other etch-grounds but it also represents the most basic means to create etched marks on a metal plate and in the context of open bite it deserves to be regarded as a technique in its own right. Open bite etching is one of the most idiosyncratic intaglio methods and can be used to create unusual and powerful effects. Future floor varnish makes a good stop-out but is quite runny in consistency.
Solid brush marks are easier to make with a custom made stop-out solution. There are an increasing number of waterbased acrylic binders and paints on the market and research has shown that many can be utilised as etching resists. It is expected that soon there will also be soy and plant based acrylic resists and grounds.
The main criteria these materials must meet is good mordant resistance on the one hand and the capacity to be easily stripped off the finished plate, on the other. A lot of acrylic paints developed for painting make quite a reasonable stop-out varnish for shorter etches but tend to break up during more vigorous biting. Many pure acrylic binders used in painting such as Golden GAC 200, possess great etch resistance but some may be difficult to strip off the plate. A product that is both highly resistant as well as fast and easy to strip is Lascaux clear gloss varnish. This resist is so strong that it survives even hours of erosion in a strong Edinburgh Etch or even a bite going all the way through the plate, without breaking up. It is also one of the few strong acrylic resists that allow clean lines to be drawn into it without the occurrence of dragging or chipping.
For most etching tasks a medium strength or regular stop-out varnish which is opaque, brushes out fluidly and is quickly removed in sodium carbonate stripping solution is recommended. It is made up from equal quantities of black acrylic paint and a strong binder such as Golden GAC 200 or Lascaux clear gloss varnish No 2060. The quantity of acrylic paint in the mix can be reduced to 25% for maximum strength. This lends itself particularly well to those seeking a very deep bite. A clear stop-out varnish that will allow underlying marks to remain visible can be obtained by using pure Lascaux 2060.
Normally an acrylic stop-out varnish is used neat but if tonal and textural wash effects are desired it can also be diluted with water.
Keep your varnish in airtight containers (acrylic paint bottles are ideal) because it hardens very quickly. It is also more economical if the required amount can be dispensed sparingly onto a piece of card. Brushes and other implements can be cleaned quickly and easily with soapy water while the varnish is still wet. If bits of acrylic have hardened on a work surface or on tools, these can be removed with Ajax or by soaking in dissolved soda crystals.
Regardless of what kind of stop-out varnish is chosen for a project it is essential to allow the stopped-out plate to dry and cure fully. Often artists who are eager to commit their work to the mordant think that the varnish has hardened when it is in fact still be wet beneath the crust. Grounds that have not completely dried can easily be dissolved in the bath as both the liquid acrylic as well as the ferric solution contain water. For this reason the use of a drying cabinet is recommended.
Stopped-out plates should be left to dry for at least 2 hours before their immersion in Edinburgh Etch or ferric chloride.
MATERIALS
Products and equipment needed to make up stop-out varnish:
Golden GAC 200 or Lascaux clear gloss varnish, No 2060
Lascaux studio acrylic paint, or similar
Variety of brushes
METHOD
Make up stop-out varnish as follows:
REGULAR STRENGTH:50% Black Lascaux Studio, No 526
+
50% Golden GAC 200 or Lascaux clear gloss varnish No 2060
EXTRA STRONG:
best for steel, zinc and any long etches
25% Black Lascaux Studio, No 526
+
75% Golden GAC 200 or Lascaux clear gloss varnish No 2060
Direct Stop-out marks and open bite
You can compose an image directly on a prepared plate with stop-out varnish. Brushes of various shapes and sizes allow a fluid and painterly way of working. The thinking an artist should apply is typical of many of the processes in intaglio printmaking: regard the plate as a background that will be eroded and from which you will shape islands of light. All the brushmarks applied using stop-out varnish are negative marks which will remain raised while the areas surrounding them are positive and will be eroded to form a landscape of canyons that will ultimately hold and then transfer ink onto the paper. Larger areas of metal that are exposed or covered but have no narrow grooves are often referred to as open bite as opposed to the more enclosed etch of line bite or aquatint. Open bite produces very distinct results on different types of metal. The resulting image from an open bite will be made up of an eroded ridge around the painted marks.
It is also possible to use stop-out varnish to create narrow grooves and textures. Simply brush out the varnish in a streaky fashion to produce bundles of heavy lines or use dabbing devises like rags or sponges soaked in stop-out varnish to add a variety of tone and texture. After etching and stripping the plate more layers of open bite marks can be added to enhance the complexity and depth of work.
In addition to the stop-out varnish there are many other exciting ways of making etch resistant marks on the plate that strictly speaking are also open bite techniques. The artist may wish to stick pieces of adhesive tape to the metal surface; draw with waterproof felt tip pens or soft litho crayon to give a textured line; or make drip marks with waterbased glue (PVA or similar). Greasy resists such as Vaseline or margarine can be smeared onto the plate – the possibilities are extensive and it is left to the imagination of the printmaker to explore their own open bite vocabulary.
Stop-out: an essential aid
Despite its own creative possibilities, stop-out varnish is most often used as an aid to other etching techniques. In this instance it does not function as the main source of intaglio mark but as a medium with which marks produced can be totally or partially protected from the corrosive process. The varnishes described earlier are well suited for this task as they bond extremely well with any kind of acrylic ground that has been applied to the plate. The depth and complexity of many Rembrandt etchings is a result of repeated etching of the plate with stopping-out taking place between each etch. Very fine work that is carried out first and etched for a short period would become a deep intaglio if it were not covered by a mordant resist before all subsequent immersions.
Choose a stop-out varnish of an appropriate consistency for different stopping-out tasks. A slightly diluted strong stop-out varnish is ideal for filling in very delicate marks and lines without covering any adjacent areas. The strong stop-out varnish in its pure form is very good for covering areas that are exposed to very deep etches or to cover up deep intaglio that has already been etched. A medium strength stop-out varnish is well suited for preserving aquatinted plates which are to be bitten in stages to achieve a broad tonal range. Owing to their thickness and plasticity most stop-out varnishes are less suited for use as a ground into which lines and other marks can be drawn or scraped but Lascaux 2060 is an exception to this general rule. However, very interesting combinations of the tonal effects of open bite and the decisiveness of line work can be achieved in one stage if marks made with a suitable stop-out varnish are then worked with a drypoint needle or other utensil. For this purpose the linear grounds should be employed i.e. the roll-on or liquid hard ground. If the floor varnish based hard ground (today: ‘Pledge’) is used for stopping out it should be brushed on more thickly than in its normal application, or in two successive coats.
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