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waterless lithography

Note 1: This is an abridged & reworked version of a description of the latest developments in waterless lithography by Ross Zirkle, published in Printmaking Today, spring 2000. It has been adapted to reference materilas & products which may be sourced in Australia. Co-edited by Annie Day & Sandra Williams.

Note 2: The dry copier toner process for lithography was developed & perfected by Nik Semenoff in 1985. He demonstrated it at the 1990 Tamarind Symposium in Albuquerque, NM. In 1990, he developed a process to make waterless litho plates from common aluminium plates by using ordinary caulking silicone.

benefits

Waterless lithography is safer than traditional lithography. Plates may be re-used a number of times & may be printed by hand or by press.

the materials

Plate

The back of second hand aluminium commercial plates or the back of used photopolymer plates may be used. Prepare the plate & give it some tooth by scrubbing it, using a sponge, with a cleanser such as Jiff. Rinse the plate with clean water, blot and allow to air dry.

Clear Silicon Seal

Purchase unpaintable, clear silicone sealant from the hardware shop. Many varieties are on the market but those sold as ordinary caulking seem to cure & reject ink well.

Odourless Paint Thinner

Because the silicone is very thick as it comes from the cartridge, it must be diluted to a usable solution. Odourless paint thinner is the best solvent and available in Art Supplies stores. Use a small container with a tight cover if the silicone will be used over a few days. Start by adding only a little solvent and stir it in. Add solvent to the silicone and mix into the proper consistency (very light syrup). Mixtures of around 70 percent odourless paint thinner to 30 percent silicone seem to work the best.

Drawing Materials

Water-soluble drawing materials like Omnichrom pencil and gouache, can be washed out with plain water. Drawing materials include:
Staedtler Omnichrom - a water-soluble pencil sold in drafting supplies and some art stores. Used for drawing effects.

Sumi Ink - an inexpensive black ink. Can be modified with dextrin or other water-soluble glues to make it impervious to the silicone. Used for pen lines or solid flats.

Gouache - good for flat areas.

Toner - dry copier toner washes used for reticulated textures - toner mixed with Isopropyl alcohol is excellent. Compressed toner can give charcoal effects.

Water-Soluble Pencils - there are a number that can work, but they have to be heat set or they become soluble in the silicone/odourless paint thinner mixture. Even some washable felt markers will work if heat set. As the drawing materials are heated they at first take on a glossy look, and then become dry as the image is bonded to the plate. Experimentation with the pencils, crayons and felt markers readily available is a good idea, as many may work.

Caran D’Ache Neocolor II - a crayon that produces a darker mark but is slightly affected by the coating solution unless heated.

Ballpoint Pens - will produce a beautiful thin line when used with the smooth backs of reclaimed plates. The images have to be heated to resist the application of silicone.

Gum Arabic, Spray Paint & Toners

Gum Arabic - used to block out white areas or 'flats' can provide a variety of tones and effects. After applying the Gum Arabic, spray the plate with spray paint as for aquatinting. Spraying helps hold water-soluble drawing materials in place while using toner washes. The spray paint needs to be hardened on the hot plate or with a hairdryer but be careful not to burn the Gum Arabic or it will not wash out. Gum Arabic flats need to be carefully washed out before the silicone is applied.

Toner Wash - a toner wash can be made by mixing used photocopy toner with Isopropyl Alcohol, toner with One Go floor polish (but should be fused to the plate with heat, and needs to be washed out with acetone, because the heat will change the nature of the toner wash), or toner with water and a drop of dishwashing liquid.

the process

Applying the Silicon Coating

After the toner image is set with heat, or water soluble medium is applied, the silicone solution which has been thinned to the consistency of light maple syrup, is spread over the entire plate and buffed down.

Use a sponge for spreading the silicone and a separate clean sponge wrapped in Kleenex for buffing the silicone cleanly and evenly. Every fingerprint or variation in silicone thickness will print, which is another reason why the silicone should not be applied too thickly. If the artwork is a bleed print, hold the plate outside the image area. While applying the silicone the plate can be held down in areas where fingerprints would not show, such as areas with heavy toner washes.

A technique was developed by Ross Zirkle for buffing silicone that looks very similar to wiping an intaglio plate. Let the palm of your hand support the plate and pull the sponge towards yourself.

You do not have to leave a very large amount of silicone on the plate. It is better to apply two thin applications rather than one thick one to get a good surface as too thick a layer of silicone is the cause for the loss of fine tints, producing highly contrasting images.

Curing the Silicon

It is extremely important that the silicone is properly cured as it can be damaged when the toner image is washed out. Allow the silicone to cure naturally at room temperature overnight. However, an oven set at 120 centigrade will do the job in ten minutes. A hot plate will work too but avoid hot spots, which can affect some drawing media such as Sharpie pens which if over-heated will not wash out. If you can raise your plates off the hot plate using old oven racks or wads of newspaper, this is helpful. Heat and the possibility of damaging the drawing media can also warp the plate causing registration and rolling problems during printing.

Rolling Out the Ink

The ink should be rolled out before washing out the image thereby allowing it to tighten up a little on the slab before the plate is inked. It is better not to leave a freshly washed out plate in an open state. This can cause some damage to the image especially on a plate where the silicone has not been totally cured. Small hard rollers are best for smaller plates. A lean ink film will generate better tack than a thicker slab.

Rolling Up on a Sub Plate

sheet of plate glass that has been grained and coated with the diluted silicone makes the best sub-plate as it is perfectly flat. About once a year, clean the surface very well with solvent and apply a thin fresh layer of silicone.
Start your roller on the sub plate off your actual printing element. It is best to roll fairly quickly across your plate diagonally, not stopping, until your roller is completely off the plate and resting again on the sub plate. This rolling pattern is repeated until the plate is fully inked. If the plate takes ink properly you can relax and enjoy the run. It is now time to move your fully inked plate to your press bed for your first impression.

Suitable Rollers

Good synthetic rubber rollers are the best to use. Brisk rolling with a rubber roller will give you good results. If there is tinting along the edge of the plate, use a small diameter brayer and go over these area quickly to remove the ink. The brayer can be rejuvenated for the next pass by rolling over an old telephone book page or other paper.

A very slow roll with plenty of pressure may be required at first for the ink to stick, but a fast roll across the entire plate will lift the tinting. Do not stop or change direction in the middle of the plate because that will leave a tint line which may become hard to get rid of by rolling. Over-inking has to be removed with a sheet of newsprint run through the press.

Suitable Inks

The ink that is needed for waterless lithography has to be of high viscosity, non-greasy and with high tack to start with. Some black inks work very well just as they come from the can but others will need modifiers. Ross Zirkle found Van Son rubber-based inks to be near perfect. Van Son rubber-based inks have much stronger pigmentation than some other popular brands.

Suitable Papers

Soft papers can absorb ink under pressure and give the most accurate impressions. Calendered, or very smooth, papers can produce very fine impressions when the pressure is adjusted properly.

Washing Out the Image

If using water-based materials for the image wash out carefully with water. Gum Arabic flats need to be carefully washed out before the silicone is applied. Wash out the toner with pure acetone. Pour the acetone first on the tissue. Use small circular motions to soften the toner and remove the major portion. Do not attempt to completely clean that area of the plate but continue removing the greater part of the toner, especially thick areas. On the first attempt you will leave a thin veil of toner over the image area but this can be more carefully removed later with fresh tissue. It may be necessary to apply acetone to the entire non-printing area of the plate to remove the thin layer of silicone oil that some silicone compounds leave on the surface. This will depend on the brand of silicone you are using.

As soon as all of the toner is dissolved, it is quickly washed off with water and a sponge and the plate dried.

Plate Storage

When printing or proofing is finished, do not wash the ink from the plate. On a number of plates where the ink was removed before storage, the silicone seems to have crept into the fine image areas and prevented reprinting of the plates. The ink protects the metal surface from oxidization and it can be easily removed later with acetone. Keep the plate in a zip lock plastic bag.

Plate Cleaning

After the edition is printed, it is possible to remove the silicone then scrub the surface with a coarse 3M scouring. More details at http://homepage.usask.ca
The formula used by Nik Semenoff to remove silicone:-
Ammonium bifluoride crystals - 1/16 oz. by volume
Phosphoric acids - 3-4 oz.
Water - 32oz.

Some safer silicone removers are used in the automotive and building trades. Add food coloring to make solution very red to discourage getting it on skin. Use all chemicals with great caution.

troubleshooting printing problems

If the plate is scumming badly, roll it vigorously with clean brayers to clean it up. Sometimes with just this step and some proofing, the plate will straighten up. The cause may have been that the plate was not properly washed out.

If the plate still is scumming badly then assume that the silicone may have been applied too thinly. Clean up your plate as much as possible by rolling it with small brayers. Then add another coat of silicone leaving ink in the plate to protect your image. Do not worry if all the non-image areas cannot totally clean up as they will clean up in the process of applying fresh silicone. Adding another coat of silicone will improve the ink rejecting property of your plate If the plate does not take ink, roll slower and add a little downward pressure. If the plate still is not taking ink, the silicone may not have cured long enough before wash out. This would allow the silicone to travel from the non-image areas to the image areas causing the entire plate surface to reject ink. If small portions of the image are lost they can sometimes be replaced in another colour run or added back into the original plate by scratching away the silicone where it doesn't belong.

some references

Semenoff, Nik. Superior Tusche Washes LEONARDO, Volume 20, Number 1, 1987, pp 71-77.

Semenoff, Nik. A Lithographer's Notebook, Saskatoon: Semenoff, 1989.

Semenoff, Nik. Waterless Lithography Using Traditional Grained or Commercial Photosensitive Plates, LEONARDO, Vol. 26, No. 4, pp. 303-308, 1993