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.
Emily McCoy, polyester plate lithography collage, 2010
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 print shops still use fountain solution and strong acids for printing and processing, but the samples shown here are all made without the addition of harmful chemicals such as glycol ether or plate etching chemicals. 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. Our solution is simply to use a wiping solution that is fortified with a small amount of gum arabic and a sprinkling of citric acid (both are safe staples of the food industry). The gum makes the plate more ink loving, and the citric is particularly helpful in preventing scumming, and ensures a clean print.
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.
(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 tar, 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 lithography
Polyester 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 Shields, 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 well-dampened paper, and rub thoroughly 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. 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
(below) John Donatowicz, polyester plate lithography drawn with a ballpoint pen, 2010
Direct 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
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. Crayons made from resins, acrylics, or hard wax should be ideal for resisting wear and would be ideal for this method.
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
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. Some acrylics tend to chip off the plate during printing. These chipped areas can often be touched up. Avoid curling the plate during roll up or excessive handling to help avoid chipping.
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.
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
Polyester Plate Printing
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. Also, as in commercial offset lithography, it is advisable to make a number of proof prints on newsprint before editioning a plate. A plate that undergoes repeated wiping, ink charging, and proof printing cycles becomes more ink loving and produces crisp and reproducible results.
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.
METHOD
Lithographic Ink
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.
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
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 (anti freeze), 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 ˝ teaspoon of citric acid powder to the wiping water (water + gum arabic).
- Dribble onto areas where scumming has occurred.
- Gently wipe with a sponge
- 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.
For a quick proof with good registration you may try inversion printing: lay the damp paper on the press bed, flip the polyester plate face down and register the plate directly to the sheet of paper.
Cleaning
To clean the plate, run it through the press a few times with newsprint to absorb excess ink, then wipe it with concentrated dish soap solution. (TIP: Use a ratio of around 1 part dish soap to 10 parts water to obtain a strong detergent that is powerful enough to dissolve any greasy ink residues.) Stubborn ink residues can be removed with toothpaste applied using a soft cloth. 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.
To get good results in multi plate color printing it is particularly important to clean plates thoroughly after each printing stage, otherwise ink will be contaminated when recharging the plates. Use a three-step cleaning routine for each plate:
-
Run off residual ink onto newsprint.
- De-scum the plate with wiping solution to remove ink offset from other plates.
- Dispense a blob of toothpaste onto a soft rag and use this to completely mop up any ink residues from the plate then clean and de-grease the plate with strong dish soap solution.
Make sure you are using separate sponges and separate wiping bowls for each color to avoid cross-contamination.
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. Many artists use the pronounced differences in printing on wet or dry paper to good creative advantage: printing on dry gives a grainy very lithographic look, printing on wet gives a dense impression almost like an etching.
Registering 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. Indrani Nayar-Gall developed a simple pin registration system for printing thin CMYK pates on an etching press which can be used for polyester plate printing. Follow the link for her detailed instructions: Perfect Registration.
Four Color Polyester Plate Lithography
Joan Hausrath, four color polyester plate project: final print, set of CMYK plates, detail
The artist Joan Hausrath writes on her four color process: "These plates were made by using Photoshop in CMYK mode. Each plate was printed using Channels for color separation. Registration was easy – I used Photoshop to put registration marks on each plate, positioning them a couple of inches away from the image. Then when I printed the first plate in yellow, I inked the registration marks with black. For the three plates that followed, I did not need to ink the marks, but used them on the plate to match up with the marks already printed on the paper. The translucency of the plates makes it easy to position the plates. I printed the plates with an HP LaserJet. To make sure the carbon adhered to the plate, I ran the plate back through the printer and on a blank Photoshop image so the plate got heated a second time. The paper was Arches 88 printed dry on an etching press – no blankets, but several sheets of newsprint instead. (Dry paper eliminates the expansion factor that can be tricky for registering on damp paper.) The inks were Handschy process colors with a bit of magnesium carbonate mixed into the magenta. (I learned that if I was printing on a hot day, I had to keep the inks cool so I put them in a small ice chest with some ice cubes.) Each color had to be completely dry before the next color was printed so that the ink on the paper would not offset onto the plate. The four color print took four days to print."
"The halftone screening function of most laser printers is accessed through the OUTPUT and SCREEN button displayed in the PRINT menu. You can either use the printer's default screen, or type in your own preferred dot size, screen angle, and dot shape."
If you examine the dots of ink on the paper with a loupe, you can see that they do not lie on top of each other, but are positioned so they print separately. This is thanks to Photoshop color separation. It is also possible to print multi-color prints (non-color separation) using Pronto Plates by using this same registration system. The colors can be developed on Photoshop using layers, and then registration marks printed on the plates. For non-digital images, use a photocopier to make the plates or draw directly on the plates and then make the marks on the plate by hand using a fine Sharpie pen. Again, the only marks that need to print on the paper are from the first plate. The marks on all subsequent plates are used as guides in positioning.
Creating Polyester Plates using a Digital Photocopier or Laser Printer
Many of the latest generation photocopiers are ideally suited for imaging Pronto Plates. These machines give a dense toner deposit which is automatically heat-fused to the plate surface, so no additional heating is required to give a stable and editionable lithographic plate. The HP A3 sized laser printer (HP 5000) also comes especially recommended for polyester plate lithography as it operates with a higher fuser temperature than some other models, making it ideal for creating stable lithographic printing plates. Despite their thinness, toner-fused polyester plates can be very durable; in industry they are used for print runs of up to 20,000 copies.
HEAT SETTING TIP: Routinely run your plate through the laser printer or copier a second time or more (without an image); the additional fusing run will ensure sufficient heat setting. This is the best way to make lasting plates and to avoid plates breaking up during printing!
Kevin Haas, Associate Professor at WSU, has put together a guide on polyester plate lithography using laser printers.
Click to download Kevin Haas' PDF guide to polyester plate lithography
(Above) Kevin Haas, Momentary Shift I, Tri-Tone Separation from video still, 2003, 3 runs
"No processing chemistry is required — just wet the plate and roll up with litho ink!This 12" × 18" (305 mm × 457 mm) polyester lithographic plate has the elegant drawing surface of a finely grained stone. Image it directly through a laser printer for extraordinary resolution,
Polyester Plate Lithography for Fine Artists
George F Roberts
2001
currently out of print
