Polyester Plate Lithography SEARCH THE SITE
GEORGE ROBERTS developed Polyester Plate Lithography, a new and nontoxic form of lithographic printing while he was Professor of Printmaking at Boise State University.
George sadly died in 2001.
Lindsey Strawn rolling up a pronto plate, Columbia College Chicago
The process is more straightforward than conventional lithography as the plate does not require chemical processing in the form of etching with nitric acid etc. Some workshops use fountain solution for printing but the samples shown here (opposite) are made without this addition. The most common problem encountered when printing a polyester plate is "scumming", when the plate starts picking up ink in areas where it is not wanted. The solution is to use a wiping solution that is fortified with a small amount of gum arabic and a sprinkling of citric acid. The citric addition is particularly helpful in preventing scumming, and ensures a clean print.polyester plate lithography mark making sample
The clarity of the print is largely determined by the consistency of the ink. An ink that is too soft and viscous (oily) will result in smudging, while a very stiff ink gives a crisp mark, but makes a heavier demand on the durability of the plate. An overly stiff ink may even rip toner marks or other drawing media off the plate during rolling up. As a remedy, use a softer ink and ensure an amount of heat curing before printing. As most of the drawing media used in Polyester Plate Litho are akin to the materials used in ACRYLIC RESIST ETCHING, many of the requirements are similar. Acrylics like heat to aid polymerization, and the new litho process is no exception.
(above, opposite)
Bernadeta Szopinska
polyester plate lithograph made using a range of oil and litho crayons, Sharpie, ballpoint pen, and acrylic wash media
Columbia College Chicago, 2008
Traditional lithography
When Alois Senefelder invented lithography in 1798 it represented a genuine innovation in the repertoire of printmaking techniques. Existing methods, such as etching and relief printing, used various means to produce a shallow relief to take the ink that would then create the final image. Senefelder’s method was fundamentally different: the flat printing surface was porous as well as water loving, and the image was formed by applying greasy media to a stone. The printing process took advantage of the fact that grease and water repel each other. When greasy printing ink was applied with a roller, it stuck to the deposit of greasy tousche or crayon but was repelled by the moistened surface around these marks.
In traditional lithography, this basic methodology is enhanced through highly complex and finely tuned chemistry involving the use of tallow, acids, soaps, solvents, and so forth. Unfortunately, many of these very things are detrimental to health, and elaborate safety measures are needed to practice this type of lithography with any reasonable degree of safety.
Nontoxic lithographyPolyester plate lithography has the advantage of being a user friendly, accessible, and safe printmaking method. Initially designed as a cheaper alternative to aluminum plate offset litho in commercial printing, it has now been embraced by the printmaking community.
Since its introduction in the late 1990s polyester plate lithography has become increasingly popular with artists and educators experimenting in the medium of lithography, and for the production of small to medium sized editions of lithographic prints. In many ways, the nontoxic process is less complex than traditional methods of stone and metal plate lithography.
Laura Sheilds, polyester plate lithograph
The materials and equipment needed for polyester plate lithography are easy to obtain. Printmaking suppliers stock polyester plates (e.g. Pronto Plates), and the required drawing media are commonplace. Any etching press can serve as a lithographic printing press. Even printing by hand is possible with polyester plates: ink the plate, place it in contact with the paper, and rub from the back with the back of a wooden spoon to make the impression.
Many artists are familiar with the process in connection with xerographic plate making, where the image is derived from a photocopy or laser print. Polyester plate lithography is equally capable of reproducing an extensive and expressive range of hand-drawn marks, lines, washes, and reticulations. Although the creative scope is not quite as comprehensive as with a stone lithograph, the medium can be mastered within hours, and the resulting prints have a fresh and vibrant feel that is genuinely lithographic in character. Lithographs often exhibit a lightness of touch and a likeness to the medium of drawing: polyester plate lithographs convey this aesthetic beautifully, and with ease.
(above) Antony West, polyester plate lithograph
Drawing on a polyester plate
MATERIALS
Products and equipment needed to draw on a polyester plate:
- Polyester plates e.g. Pronto Plate
- Waterproof Sharpie pens (various thicknesses)
- Ballpoint pens
Two tried and tested utensils for drawing lines on polyester plates are waterproof Sharpie pens (also try the new Paint Sharpies which give added opacity) and regular ballpoint pens. These types of pen are great for creating delicate yet solid lines, swirls and hatchings and allow you to achieve a pictorial quality akin to pen and ink on paper. The marks print well and stay reproducible throughout an edition of prints.
To get a fuzzy, crayon-like line it is best to use the hardest kind of lithographic crayon, such as Korn's litho crayon No 4. Press down firmly when drawing to get reproducible marks. Do not use soft litho crayons or pencils as the marks made by these will fade or wash away when printing.
Be careful not to get grease on your plates while working - even fingerprints may print!
To get a fuzzy, crayon-like line it is best to use the hardest kind of lithographic crayon, such as Korn's litho crayon No 4. Press down firmly when drawing to get reproducible marks. Do not use soft litho crayons or pencils as the marks made by these will fade or wash away when printing.
Be careful not to get grease on your plates while working - even fingerprints may print!
Painting on a polyester plate
Because acrylic surfaces possess lithographic adhesion, just as greasy surfaces do, oil-based printing ink will stick to acrylics during roll up and then print as a crisp mark. Many acrylics can serve as lithographic resist, but it is important to thin the ink sufficiently to avoid any excessive build up (i.e. ink deposits standing in relief) on the plate. Thicker layers of acrylic will cause the ink roller to skip across the surface, and you will only get a partial impression. I would recommend using any of the following three acrylics as a base for your ink.
MATERIALS
Products recommended for painting onto a polyester plate:
- Golden Acrylics GAC 200 medium
- Hunt Speedball Screen Filler
- Lascaux 2060 clear gloss varnish, or Lascaux hard resist
Once you have thinned the acrylic with 20% to 30% water, add some india ink for opacity. Use soft brushes to paint solid blobs, stripes and graphic areas onto the plate. Creating your image is simplicity itself - working on a Pronto Plate is hardly any different from painting or drawing on paper.
One of the great advantages of lithographic drawings is the ease with which you can work in the reverse. Once lines and brush marks have dried, use an Exacto knife or cutter to draw white lines or hatchings into the dark areas. You can also lighten areas by scraping off the ink.
It is best to work with a solid but not thick layer of opaque ink. Avoid thin washes as any acrylic mark, however thin, will print as black. Tones, washes, and reticulations are achieved by other means.
One of the great advantages of lithographic drawings is the ease with which you can work in the reverse. Once lines and brush marks have dried, use an Exacto knife or cutter to draw white lines or hatchings into the dark areas. You can also lighten areas by scraping off the ink.
It is best to work with a solid but not thick layer of opaque ink. Avoid thin washes as any acrylic mark, however thin, will print as black. Tones, washes, and reticulations are achieved by other means.
METHOD
Random reticulated effects are easily created using a wet on wet technique:
- Make up a strong solution of dish-soap and pour it into a plant mister.
- Paint the plate surface with acrylic.
- Spritz with the soap solution.
- Use a hair dryer or hot plate to dry the plate.
Once dry, this results in surprisingly varied and detailed reticulations.
For aquatint-like tonal gradations, use an airbrush, or simply spatter ink drops using a diffuser or a toothbrush.
To make a tonal wash medium, dissolve a few teaspoons of photocopy toner in ethanol alcohol, mix with some dish soap, and paint onto the plate. The fine toner particles distribute themselves within brushstrokes, giving the desired grainy tone.
SAFETY NOTE: Be sure to wear a dust mask and gloves when handling toner. Toner particles should not be inhaled.
Toner-based marks, in particular, require heat-setting to bond with the plate. For the best results, place your plate on a hot plate for about 30 minutes before printing. Alternatively, use an iron to heat set the plate.
For aquatint-like tonal gradations, use an airbrush, or simply spatter ink drops using a diffuser or a toothbrush.
To make a tonal wash medium, dissolve a few teaspoons of photocopy toner in ethanol alcohol, mix with some dish soap, and paint onto the plate. The fine toner particles distribute themselves within brushstrokes, giving the desired grainy tone.
SAFETY NOTE: Be sure to wear a dust mask and gloves when handling toner. Toner particles should not be inhaled.
Toner-based marks, in particular, require heat-setting to bond with the plate. For the best results, place your plate on a hot plate for about 30 minutes before printing. Alternatively, use an iron to heat set the plate.
Printing a polyester plate
Polyester plates are easy to print. During printing, the truly lithographic nature of this method - utilizing the repulsion between grease and water - is revealed. Lithographic printing typically involves alternating between wetting the plate and rolling over it with greasy ink in multiple passes until the desired density of ink has built up.
METHOD
Wiping Water
- Fill a plastic bowl with water and add one shot glass (approximately 45 ml U.S.) of gum arabic solution and half a teaspoon of citric acid powder.
- Place the polyester plate on a clean, slightly wetted inking surface.
- Now dip a cellulose wiping sponge in the water, squeeze, and pass lightly over the plate a number of times.
The pores of the plate surface now fill with tiny water droplets that will repel the ink roller as it passes.
METHOD
Lithographic Ink
Some litho inks are very stiff and hard whilst others are as malleable as etching ink. Stiff inks are thought to give the best detail reproduction, but softer inks are easier to apply and give an image greater contrast.
For a good black ink I would recommend Graphic Chemical litho ink No 1921, which has proved to be ideal for the polyester plate process. Very stiff inks are often modified with linseed oil; the litho varnish No 3, for example, will soften ink and make it easier to roll up.
Whatever the consistency, the ink needs to be worked around with a spatula for a few minutes. Scrape the ink across a 10 x 10 inch surface and then use a good roller (preferably a softer nitrile roller) to roll out the ink evenly in a criss-cross pattern. A well rolled-out ink makes a smooth sort of hissing sound while charging.
- Dispense some litho ink onto your inking surface.
- Use a circular scraping action inside the can to dispense the ink, then cover the surface inside the tin with plastic film to prevent it drying out.
- Modify the ink as required.
- Work the ink for a few minutes.
- Gently start rolling over the dampened polyester plate - you may need to hold down the edge of the plate to prevent it from curling over the roller.
- After each roll-up the plate needs to be gently re-wetted in order for the surface pores to remain ink-repellent.
It is rarely possible to charge a plate in one go. A well-charged plate usually requires the gentle and careful build up of successive layers of ink.
When a plate is freshly made, it may take from 4 to 10 ink and water cycles before it is fully charged with ink. However, once a plate has already printed, the surface becomes more ink loving and only a few inking-wiping cycles are needed to recharge.
When a plate is freshly made, it may take from 4 to 10 ink and water cycles before it is fully charged with ink. However, once a plate has already printed, the surface becomes more ink loving and only a few inking-wiping cycles are needed to recharge.
METHOD
De-Scumming
Every now and then an inking pass will leave smudges where they should not be: this is called "scumming". To remove these areas during inking, some printmaking guides recommend the addition of fountain solution to the wiping water but, as this contains harmful glycol ether, I prefer the addition of citric acid as an anti-scumming agent. Simply dribble some of the wiping water onto the scummed areas and gently wipe with a sponge.
- Add ½ teaspoon of citric acid powder to the wiping water (water + gum arabic).
- Dribble onto areas where scumming has occurred.
- Gently wipe with a sponge
METHOD
Printing
Polyester plates can be printed on a litho press, but many artists prefer using an etching press. To print a polyester lithograph it is crucial to use little or no felt material between the rollers to gain maximum contact between plate and paper. I use one thin blanket of vinyl interfacing, and full pressure.
- Gently peel the inked plate off the slab and place it onto your registration sheet.
- Lay the printing paper on top as though printing an etching.
- Lower the blanket and roll through the press.
Papers for Polyester Plate Lithographs
Lithographs can be printed on a wider variety of paper than etchings. Slightly textured rag paper can enhance the lithographic grainy look of the print. Successful prints can be made on wet or dry paper.
If a print looks too faint on dry paper, but the plate has been inked up correctly, often the use of moistened paper can rectify the problem. The result is a darker, crisp and clean image with more contrast than it had on dry paper. To wet the paper simply dip each sheet in water then blot off the excess.
Color Lithographs
Pronto plates print equally well in the reversed paper print order - this makes color printing easy and reliable. With color projects I would recommend printing the first plate face-up using a registration sheet, then all successive plates can simply be dropped into the existing plate mark onto the print. Polyester plates are ideal for making easily registered color prints because the entire set of translucent plates can be cross checked and aligned on a light box whilst working.
Cleaning
To clean the plate, run it through the press a few times with newsprint to absorb excess ink, then wipe it with detergent solution. Clean the slab and rollers in successive stages using vegetable oil, baby oil, and detergent solution (in this order). Remember that, unlike VOCs, cleaning oils are non-volatile and act best if left to soak into the ink for a few minutes. Use a spatula to scrape off excess ink to save on cleaning rags.
Creating Polyester Plates using a Laser Printer
For suppliers of polyester plates:
KEVIN HAAS, Associate Professor at WSU, has put together a guide on polyester plate lithography using laser printers.
See more of Kevin Haas' research on the university website:
Kevin Haas
5072 Fine Arts Center
Washington State University
Pullman, WA. 99164-7450
T: 509-335-7202
E: khaas@wsu.edu
Momentary Shift I, Photoplate: Tri-Tone Separation from a Video Still,
2003
3 Runs, 380mm x 510mm
For suppliers of polyester plates:
Printmaking Resources (Suppliers)
