WATERLESS LITHOGRAPHY USING
COMMON CAULKING SILICONE

 

A new process of producing aluminium lithographic plates using ordinary silicone rubber as an ink rejecting surface.

 

Developed by Nik Semenoff, June 1990, University of Saskatchewan, Saskatoon

 

Historic background

Alois Senefelder discovered "chemical printing" nearly 200 years ago and since then lithography has relied on the principle that grease and water do not mix. While it has allowed lithography to replace most other media in the commercial printing area, the use of water in the process has produced a number of nasty problems for the printer. Because of this, printers have long dreamed of a system, which would completely eliminate fountain solutions and all the inherent difficulties. In the late 60's, Harry Hoehn of Long Island, NY, experimented with the then available RTV silicones. A number of years back, 3M had tried to develop a waterless system for the commercial printing trade; but after investing a considerable amount of money, they sold their patents to a Japanese company. Toray Industries, Inc., now markets a waterless process that is capable of reproducing very high quality photographic images. Since theirs is completely a photographic process, the image must be first drawn on paper or other substrata and replicated with a copy camera. Hand drawn images direct on plate are not possible, but images on mylar can be exposed on their positive plates. The cost and availability of Toray plates puts them beyond the reach of most artists.

Many years ago I became interested in the waterless concept and planned some experiments to try out some of my theories. My good intentions were put aside for a number of reasons and only in 1990 I started my research. To my amazement, the very first plate produced a very respectable print and became the basis of my process.

While it is commonly believed that grease and water do not mix, lithographic ink and water do in fact blend to some degree to make the plate work better, but too much water in the ink produces a "short" ink which is difficult to use. Some art printers believe that a small amount of water which becomes emulsified with the ink will produce better prints, and control this in a number of ways. The fact that water has less cohesion than ink, the separation of the two takes place at the water layer, leaving a few molecules of water to be taken up by the ink roller. While water has been the basis of the lithographic process, elimination of fountain solutions would be better for the media. What was needed was a material on the non-printing area that would not be liquid at the time of printing.

Another problem common to lithography is the chemical inter-action at the surface of the metal plate. The sensitive metal surface will bond with any carboxyl molecules that are present in many greasy materials and some gums, thereby producing the areas of image and non-printing background. It is the remaining portion of the molecules that either accepts or rejects grease or water, depending on whether a CH (hydrocarbon) or OH (water) segment is presented to the ink roller or dampening sponge. Because the metal will accept either molecule, (as long as the carboxyl portion is present), the plate can go blind, or become too dark, as the materials are disturbed and replaced by the other type of molecule. If the two areas depended on totally different chemistry, a more stable plate would be the result.

A process that would eliminate some or all of the toxic materials now used by printers would certainly be highly desirable. Materials should also be easily available and not too expensive. Anything that would simplify the processing of plates and produce long running clean images from direct hand drawn plates could become an important addition to the artists lithographic process.

Properties of silicon

Silicon is one of the most abundant elements in the universe. It is present in many rocks and is the major constituent of sand. We have for centuries used it to make glass and have manufactured lenses, laboratory utensils and other scientific equipment from it. Science has converted silicon into many forms ranging from a soft rubber-like material to hard-as-stone compounds. It is responsible for the transistor and the computer chip that makes radio, television and computers everyday consumer products. In many forms, it becomes a very stable material that will endure for many decades, or even centuries.

As a rubber-like compound, it is used for glue and a very effective sealer for water as a caulking compound. Some of these products retain silicones affinity for itself, and some other materials -- and the rejection of other compounds. Taking advantage of this characteristic, we can produce a non-printing layer on an appropriate substrata to produce a waterless lithographic plate. The availability of many commercial sealing products gives us a freedom of choice and at the same time adds to the confusion of which works best for our purpose.

The material used

My approach is to secure a cartridge of clear silicone seal from the hardware which is known to be unpaintable and stated to be so on the container. These are amongst the first silicone sealers and glues made available to the public and the commonness, but are now being supplemented with paintable and water-based versions. It is important to acquire the non-paintable product in the standard solvent type of sealer. The large cartridges are the best buy and the easiest to manipulate. Many varieties are on the market but I have found that those sold as ordinary caulking to be the best for curing and excellent in rejecting ink. Various brands are available and there is some difference in the subsequent silicone layer which can have an effect on the type of ink you may use. Since it was impossible to acquire all the brands which are or will be on the market, you will have to test those you think might work, as some of these could produce even better results than those I've experimented with. Today I unquestionably recommend Dow-Corning silicone for three reasons; it has a screw in plug for better storage, is tough - making for a better ink rejecting surface, and is consistent in quality. Lately, in my part of the world, Dow-Corning silicone has been hard to find; the only supply seems to come from old stock. Since all silicone rubber materials are known to have a self life of about 2 years, I am inclined to look for newer products. Because all other silicone cartridges do not have the preferred screw in cap like Dow-Corning, one must cut off the plastic tip that allows the silicone to start hardening. The way to overcome this is to secure some Marr electrical connectors. There is one style that has a brass insert that screws into the hard plastic shell. Discard the brass and use the plastic shell. The number 2 size seems about right when you cut off about 1/4 inch of the tip. The inside thread of the Marr shell will grip on the soft polyethylene tip and make an adequate seal.

Because the silicone is very thick as it comes from the cartridge, it must be diluted to a usable solution. I have found that odorless paint thinner is the best solvent and easy to come by; it controls the rate of drying when applying the silicone, making it perfect for the task. It also seems to do a better job of diluting the thick adhesive in the initial stages. Start by adding only a little solvent and stir it in. Add solvent to mix into the proper consistency. The viscosity of the mixture is a matter of taste but I think a thinner solution is better as it dries faster. The silicone should be diluted to the consistency of a very light syrup. It is better to apply two or three thin applications rather than one thick one to get the best desensitization. Some substrata such as coarse ball grained plates may require a thicker coat with a more viscous solution, so experiment for the best approach - which will only come with experience. I rarely need to apply more than one coat of Dow-Corning silicone on aluminium plates, especially when I use the back of my plates.

I have discovered that the supplier of the odorless paint thinner that I was using, must have changed their formulation. The solvent had a much stronger odor, but it in fact seemed to break the silicone into parts that ruined my plates before I realized what was happening. It seemed to separate out the rejection oils from the rubber, allowing the ink to tint the clear areas; but more important, it would blind the image as the roller when over it. I have found another brand that works, but you should be aware that this sort of thing can happen, as we are using common materials not intended for printmaking in this way. While common paint solvents can dilute the silicone very effectively, there are some toners that are actually dissolved in this solvent. Most are not, but the stronger odor of Varsol can be problem for some printers.

Depending on the brand, the thinned solution can be placed in a container and kept for a long time. In schools, it would be more practical for a technical assistant to make up the silicone solution rather than count on the undergraduates doing it. By using thinner silicone and applying two thin coats, a sufficient layer can be built up quickly with the aid of a heat source such as a hot air paint stripper; this overcomes any missed areas. I strongly recommend Dow-Corning general purpose clear silicone sealant, if it is available. Because I can no longer get this silicone, I have taken to using Dow-Corning #999-A, a professional material which is available from a building contractors supplier. I am told by Dow-Corning that #999-A is the same material. You can purchase a supply and keep the cartridges in your freezer, where it will keep for a much longer period.

Instead of glass containers, one of our masters student has found small polyethylene containers with a squeeze on top that is perfect for mixing and storing the silicone. Meant for keeping excess baby food, these small containers can be reclaimed after the silicone sets up in them. Since nothing really bonds to polyethylene, the silicone film can be stripped off the inside.

Drawing the image with water based materials (The simplest method to get an image)

There are on the market a number of water soluble crayons and drawing pencils that make perfect images similar to grease crayons. The best is Staedtler Omnichrom #108-9. Draw on the plate with these water soluble crayons, feeling free to remove mistakes with water if need be. As long as the bonding agent for the crayons is removed, the plate will take silicone. If only water soluble materials are used, they can be removed (washed out) with water after the silicone coating is applied. The plate is then ready for printing.

There are a number of other water soluble pencils that can work, but these have to be heat set before they become insoluble in odorless paint thinner. Even some washable children's felt markers will work if heat set. As you heat these drawing materials, they at first will take on a glossy look, then become dry as the image is bonded to the plate. Experiment with the pencils, crayons and felt markers you have on hand, many may work. Neocolor II by Caren D'Ache is another that produces a darker mark but is slightly affected by the coating solution unless heated. Many ballpoint pens will produce a beautiful thin line when used with the smooth backs of reclaimed plates. These images have to be heated to resist the application of silicone.

For solids and pen work, ink made up of glue and a coloring agents works very well. I found dextrin better than gum or glues because of the fluidity of the adhesive. Make up a reasonably viscous mixture of dextrin in hot water and let cool. Add cheap Sumi ink to give you a dense black. This ink can be applied with brush or pen and can be removed if changes are needed. Unlike traditional processing on metal plates, silicone will allow you to scratch white lines into solid areas, like into stone. By using water soluble drawing materials, it makes this technique probably the easiest and best approach for waterless litho as the image can be washed out (developed) with plain water. Sumi inks are heavily pigmented, but do not have enough binding media to act as a mask for the silicone. Add any soluble glue solution to increase the binding medium, which is in fact the imaging material.

Using toners and plastic materials

Using my toner tusche wash process on aluminium grained plates is another approach. With toner, draw an image as a tusche wash - toner chalks can be used as well. Any material that will not be affected by odorless paint thinner, yet can be dissolved in acetone or water is a likely candidate for drawing. Shellac, floor polish emulsions, and cut Mac-tac film are good for certain type of images. The Mac-tac can be stripped from the plate surface after the silicone has been cured. Spray lacquers can be used for air brush effects, as long as the lacquer can be removed. For pen line work, a simple ink made up of one of the new acrylic floor polishes (Future) and Sumi ink for color, works better than liquid tusche or autographic ink does in traditional lithography. This quick drying plastic material can also be used to produce large solid flat areas. Since the grease reservoir is not needed or desirable, all that is necessary is to produce a mask to protect the metal surface. Acetone will wash out or "develop" the plate for printing (see my toner paper or the Leonardo article published in 1987). Unless the waterproof characteristics of acrylic emulsion is needed, I recommend you use water-soluble materials for flats.

Using grease and other materials

Common lithographic grease crayons cannot be used directly with the waterless process as they will be dissolved by the solvent present in the silicone coating solution. Traditional grease materials can be used, but require special consideration which I will discuss later under conversions.

Applying the silicone coating

After the toner image is set with heat or white gas, or when water soluble medium is used, the silicone solution, which has been thinned to the consistency of light maple syrup, is spread over the entire plate and buffed down. Use small foam rubber pads to apply the silicone, as they are much gentler on the image than cloth or paper. These can be acquired as scrap from upholstery shops or bought from department stores selling such products. Do not pour too much silicone on the plate as only a thin coat is needed. You do not have to leave a very large amount of silicone on the plate as a thin layer seems to works as good or better than a thick one on most surfaces. It is important to buff the plate to an even layer using facial tissue, as streaks can produce faint lines. I use a larger foam rubber pad as a backing to the facial tissue; this produces a smoother surface on the pad and makes a very even layer on the face of the plate. Allow the silicone to cure at room temperature or you can hasten drying with a hot paint-stripper gun. It is extremely important that the silicone is properly cured as it can be damaged when you go to wash out the toner image. If there is any doubt about the integrity of the silicone layer, I would put on another coat after the first has cured. Do not produce too thick a layer as it will be difficult to develop the image and you will harm the silicone surface during washout. Too thick of a layer of silicone is the cause for the loss of fine tints, producing very contrasty images.

I have found that the silicone becomes extremely durable if allowed to cure for some time; as my older test plates seem to resist all attacks on the coating. Although printing can proceed immediately, leaving the plate to cure overnight might not be a bad idea.

Silicone Intaglio

While I have not discussed this simple imaging method in this paper, I have shown it to printers at my workshops as it is a well know principle known to printers from the early days of lithography. Even on stone, the printer would first gum etch a plate by add pigment to the gum so the scratches can be seen much easier. After the surface is scratched with an etching needle, asphaltum was rubbed into the image and roller up as a processed plate. Metal plates worked the same way and many artists made simple additions to an image by scratching through the desensitized gum layer. Today, this technique is being promoted as an original method, using commercial Toray plates and suitable inks.

With the cost of Toray plates, I am surprised an artist would use them for such a simple technique. In place of using Toray plates, one can use the backs of used aluminium plates, which have been first coated with silicone. A number of artists at my workshops have used the technique to produce beautiful delicate images, that would print any number in the edition. See my paper on recycling plates over and over again for the method of reusing plates. After the edition is printed, the silicone can be removed and the surface scrubbed with a coarse 3M scouring pad to eliminate the scratched lines on the surface. I have found any trace of a line will not become a problem, if the stripping and cleaning was effective.

Stripping off the silicone for adding to the image

Because silicone sticks so tenaciously to the plate surface, it is more difficult to make image changes than counter etching a traditional gum plate. After much research, I have found a chemical that works. While strong organic solvents will dissolve and remove the silicone, it is difficult to eliminate all traces of silicone from the surface. Even a very thin film will prevent the new image to take hold, allowing for a possible plate failure during editioning. What is needed is a solution that strips off the silicone cleanly and not dissolve even a small portion of it. While strong acids could be made to attack the metal under the silicone, experiments showed this was not a practical method.

In the end I have decided to use fluoride compounds as this element attacks silicon on contact. While a weak solution of hydrofluoric acids works, the dangers of using this chemical goes completely against my search for less dangerous materials. After some experiments, I have found that a very weak solution of ammonium bifluoride and acid does the job perfectly and should not be too dangerous in the concentrations I propose. A small amount of ammonium bifluoride crystals are dissolved in water to form a solution. Do this in a plastic container as fluorides attack glassware. To force students into putting on rubber gloves and so prevent any absorption of the chemical, add a large amount of a strong red dye which would stain the hands - it also aids in applying the stripper. I also add a reasonable amount of acetone to act as a wetting agent on the silicone and help remove ink. Wheat flour is added to increase viscosity to reduce beading on the silicone surface. The formula which I recommend is as follows:

 Ammonium bifluoride crystals

  oz. by volume

 

 Hydrochloric or phosphoric acids

  -1 oz.

 

 Water

 8 oz.

 

 

 

* Add food coloring to make solution very red

* Add acetone if ink removal is wanted; dispense with the acetone if the image is to be retained.

* Add wheat flour for increased viscosity

The amount of chemical can be varied according to your experience and nature of the plates. Use weaker solutions at first, or if you want to retain some of the image. Because of the harsh action of this stripper, it is difficult to hold the image. By applying rosin to the wet ink and heating the plate, more of the image is saved. On an old plate, test the effectiveness of the stripper by applying it to a small area with a brush or sponge. If there is a heavy coat of silicone, the solution will likely want to bead and no amount of acetone seems to help. Keep the solution moving over the area, this will have the desired effect on the silicone. You will notice a slight resistance to the movement of the sponge where the silicone is being removed. After a minute or two, take a wet foam rubber sponge and wipe off the stripper. If the solution is strong enough, the affected area will become wet with water, indicating the loss of the silicone layer. If an ordinary urethane sponge wet with water is rubbed on the area, it is much more effective in removing the silicone as it acts like an eraser. A stiff finger nail brush also helps displace the silicone.

Try to reduce the amount of ammonium bifluoride in your solution by now taking a small portion of your mixture and try diluting it with more paste. There will come a point that the solution is ineffective even after leaving it on the surface for a long time. Try for a solution that will work in about 5 minutes, and so reducing the dangerous chemical to the minimum. The heavier viscosity of the solution is necessary to reduce the beading and allow for more controlled stripping. Adjust all materials to conform with the typical thickness of silicone you use on your plates. If you want to use a fine brush in get into intricate detail, then a thinner solution would be needed. Larger areas would benefit from a more viscous mixture.

In the end I have reduced the hydrogen fluoride content to about 3% or less. No fluoride gas would be escaping from this mixture. My test solutions read 3.9 - 4.5 pH on my pH meter. It is important that you use rubber gloves to farther reduce the dangers of using fluoride compounds. Ammonium bifluoride is also called ammonium hydrogen fluoride, which indicates that part of the compound contains hydrogen fluoride, or hydrofluoric acid. We encounter fluorides in toothpaste and drinking water everyday. At the low concentration in the stripping fluid, and with common sense, I see less problems with it than many chemicals we use in printmaking, but special care must be taken when working with an fluoride. Similar chemicals are used by stained glass workers to frost areas of their pieces. With extra care, there should be no problem of using this approach to counter-etching your plates.

I have found on the market some effective products to strip of silicone. Sold in automotive supplies shops, these chemicals are meant to be used as a cleaner for magnesium wheels, and contain a small amount of hydrofluoric acid. On testing the solution, I found it had a pH of about 3.3, which is not that acidic amongst the other chemicals one uses in traditional lithography. One product is called "Mothers Wheel Mist", and the other "Eagle One Etching Mag Cleaner". I have used the Eagle One solution and found it can be diluted by three parts water, and still be effective. I would suggest pouring on the liquid rather than spraying, so that the risk of inhaling the HF molecules is eliminated.

Because of many printers concerns about using any solutions containing HF, I had the commercial cleaning products analyzed for the amount they contain. I have found that Eagle One has reduced the amount of the chemical to a degree which does not require them to list it on the label. The original solution contained 1.7% HF while the new formulation tested at .9%. When diluted with parts water and a small amount acids, the working solution tested at .36% HF. I usually add some hydrochloric and/or phosphoric acid to help clean the plate surface. The Mothers' Wheel Mist did not contain enough HF to register on the test equipment, so the chemist checked the machine but found it working properly. For some reason this product does strip off silicone, so there must be a trace of HF in the formula, which means not much of the toxic material is needed to destroy thin layers of silicone. If you are using the grained surface, then these formulations may not be effective enough. I have found that by the time all the silicone is removed from the grained surface, the grain has been eroded enough to produce practically a smooth plate.

To help make the silicone bond better to this chemically eroded area, I have found that an application of dilute sodium silicate is helpful. There must be some fluoride molecules left in the grain of the aluminium which prevents proper adhesion of the silicone over time. Since waterglass is alkaline, it reacts with any free hydrogen fluoride molecules; at the same time producing a layer of aluminium silicate for the silicone better to adhere to.

I should emphasis that hydrogen fluoride and ammonium bifluoride are very dangerous chemicals, especially in any concentrated form. While using them in the diluted solutions I suggest, there is could still be problems if a large amount gets on your skin. Wash the area with plenty of water and remove any clothing contaminated with the solution. Having a saturated solution of calcium chloride on hand would allow you to quickly neutralize any free fluoride molecules by forming calcium fluoride, a solid material, also known as feldspar. If there are children coming into the studio, any dangerous chemical must be stored safely away from them. Certainly do not store any toxic material in containers previously used for beverages.

Washing out the image (development)

Wash out the toner with pure acetone, or a mixture with diacetone alcohol - this is a developer. The developer mixture slows the evaporation of straight acetone and makes the washout easier. Five to ten percent diacetone alcohol seems to work fine, but one could use butyl carbitol instead as it is less toxic, but may cause tinting problems, unless the plate is washed with soapy water. Water is used to clean the plate before printing. Because hydrocarbons will affect the silicone, they cannot be used to removed the toner image, so acetone is used to removed the plastic materials. While the retarder slows rapid evaporation and prevents the toner from bonding to the silicone, it gives us time to dissolve more of the image until water is used for the final cleanup.

Wash out the toner image with paper facial tissues by pouring the acetone developer first on the tissue. Use a small circular motion 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 attacked 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. If this silicone oil is not removed, the ink roller will pick it up, preventing proper transfer of ink to the image.

As soon as all of the toner is dissolved, it is quickly washed off with water and a sponge. This technique can be used in most cases except when gum is used under the silicone when doing reversals. This method reduces the amount of developer and acetone used as the retarder prevents the dissolved toner tint from drying too quickly on a plate. If water based drawing materials are used, the water wash will remove them also.

There is no need to apply vinyl lacquer or any other printing base. Where the silicone rubber has been removed from the metal surface, the plate will print as the ink comes in contact with the image area. After ink is left on the metal plate for any length of time, a strong chemical bonds takes place which becomes the permanent printing base. If the image rejects ink because of residual silicone oil, just wash that area again with acetone and continue to roll up.

Because of the difficulty of obtaining diacetone alcohol or butyl cabitol, I have recently been experimenting with a commercial cleaner and degreaser that has the ability to dissolve type B toners. Called CITRA-SOLV, it is a concentrated solvent that is miscible in water. Apply the cleaner full strength and washout the image, then use soap and water to clean the plate. While it doesn't affect type A toners, it should still be useful in most shops for other cleaner functions besides image development. There seems to be a number of solvents that contain these new citrus oil additives which may give printmakers a washout solution that is less toxic. While these cleaning materials are not as good as the acetone/diacetone mixture, some may work well enough for those printers concerned with the use of acetone. If the toner you are using will not washout with straight CITRA-SOLVE, then use it as a retarder in an acetone developer. Experiment the the percentage that will effectively dissolve the toner, yet leave a moist film that can be removed with soap and water. If someone finds a better development solution, I would certainly like to hear about it. Your name can go down in history.

Using traditional grease materials

Since some artists prefer the effects of traditional tusche washes and grease crayons; these materials can be incorporated into the waterless process. Because of the nature of these materials, the process requires an additional step or two to take full advantage of the technique. Vinyl lacquer base or other masking material will be required, as well as gum Arabic.

The image is produced in the conventional way using stick tusche for washes and crayons for drawing. Any materials that will produce a impervious layer to the water based gum should work. Marking pencils with high wax content and felt markers are also all candidates as drawing tools since no acid etch is used.

Talc the image as usual and apply plain gum Arabic all over the plate. Since we are not etching the plate in any way, other gums or water soluble glues may work. All that is needed is some form of mask to protect the non-printing area from the vinyl lacquer which will be applied as yet another temporary mask. Buff the gum down to a tight film and dry. There is no advantage to let the image and gum sit on the plate as in traditional lithography, so as soon as the gum is dry, the image can be washed out with lacquer thinner or an acetone and odorless thinner mixture. Apply a coat of good vinyl lacquer and buff to a slightly thicker than a normal film. After the vinyl has dried enough to not be sticky, the gum can be removed with water. There is no need to let the lacquer dry real hard because it could be difficult to remove. This is a tricky step and experience will help you in determining the right state of dryness.

If the lacquer will not come off with a wet sponge, proceed to roll up the plate with a stiff ink. As the lacquer lifts off the non-printing areas, ink will be deposited on the image. If you have to use this procedure, then gum Arabic should have to be used for its slight etching effect. When the plate is clean, sort of wet wash the image with odorless paint thinner. This wash out technique is only used when vinyl lacquer dries too hard.

After drying the plate of odorless thinner, but making sure no moisture remains on the surface, silicone rubber can applied as on a toner image plate, then buffed down. From now on the two plates can be handled the same way. After building up the silicone layer, the plate is washed out with acetone developer to remove the image lacquer and expose the metal. Printing can proceed from here.

Converting proofed grease and photo plates

Grease images that have been proofed as gum/water images can be converted into the waterless process. Make sure that there is a good vinyl lacquer base under the grease image, reinforce it if in doubt. Remove all traces of ink with a suitable hydrocarbon. Wash off the gum. After drying the surface, apply the silicone coating as before and cure. Remove the lacquer base with acetone developer and roll up with ink.

It is very easy to convert both negative and positive photo plates to waterless lithography. I have done this with a number of different products. One make of negative plates I encountered would not convert easily as the image could not be removed with acetone. By adding a very small amount of methylene chloride to the acetone, I was able to make that brand of plate work as well. The procedure for all plates is to first remove the gum with water, rinse and dry. In fact, thin gum can be left on if multi color editions are to be made from the one plate (discussed later).

After drying, apply the silicone rubber as if it was on a toner image. Upon curing, the image is removed with acetone, alcohol or the developer used for positive plates, depending on the make of photo plate. The plate can be rolled up with ink as before. If the image is not completely removed to the bare metal, the plate should still work. As long as the silicone rubber is removed from the image, the remaining developed photosensitive material will take ink.

Processing photo plates directly as waterless

I have been able to process both negative wipe-on plates and positive photo plates directly as waterless. The acid gum etch supplied for these plates is not used as they would then have to be treated as a conversion. After exposure and plate development, the surface is rinsed with water and dried. Silicone rubber is applied and buffed down. After curing, the image is removed with acetone developer, methyl alcohol, or the plate developer, after getting a second exposure to destroy the emulsion. The diazo wipe-on negative image does not come out completely with acetone but the silicone rubber is stripped off, allowing ink to take hold. Fuji, DuPont and Hoescht positive plates worked so well that one would think they were designed by the manufacturer for this waterless process.

Making reversals of any waterless image

Working with reversals in waterless lithography means you will have to decide on the procedure before you start. Image making materials cannot be water soluble as you will use Gum Arabic as a temporary base for the silicone coating while printing the first color. While reversals in traditional lithography call for the removal of the gum layer so that the plate will accept ink, silicone cannot be removed with even the strongest acids or solvents. It is a simple matter to set up the processing to allow for the removal of the silicone coating.

The image can only be done in toner or water resistant plastics such as Future floor polish for this method to work. After the toner is set and the plastic drawing ink has dried, a layer of thin Gum Arabic is applied over the entire surface that is to be reversed. Silicone is next applied over the gum and cured, the image then developed with acetone and printed as a positive if so desired. Water must be kept off the plate as it would remove the silicone coating.

For the reversal to take place, the image is first washed with solvent to remove the ink. Make sure all the ink is removed by washing the image area with lacquer thinner if need be, as there is no fear of damaging the silicone, which is to be removed later. Apply and cure silicone over the image area to be reversed. Now take a wet sponge and cover the entire plate and let it soak into the gum layer under the silicone. You may have to rub the surface with your fingers to help lift the silicone, but this is easy to do if the silicone layer is not too thick. After all silicone is removed, the plate can be printed when dry. Borders can be produced by applying masking tape before the gum is put on the plate, or they can be covered with silicone later.

If there are areas of the plate that are not to be reversed, they can be protected with orange shellac, which is applied like lacquer base. After applying silicone to the original image to be blinded and after washing the silicone off the surface with water, wood alcohol or acetone is used to remove the sealer and reveal the original protected image. No water must be present in these solvents as it could damage the original gum still beneath the silicone that was protected by the shellac.

Using this technique to print multiple editions from one plate

Our students have found that they can print many editions from one plate if they first undercoat the silicone with gum. Some have printed as many as eight editions or multicolor plates from just one surface. After printing their edition, they don't reverse the image; instead they wash or counter etch the plate lightly. This removes the silicone and gum at the same time. For multicolor editions, the remaining ghost image is helpful to lay down the next color. For a new edition, they disregard the old image like the ghost left on screens in screen printing.

While the use of water is restricted in this technique, I have found that the Omnichrom pencil can be washed out with acetone, making it possible to do crayon manner drawings. First cover the entire plate with gum. The drawing is done with an #108-9 Omnichrom pencil, toner chalks or other materials that do not require water in application. After curing the silicone, the image is developed with acetone, but water is not used to clean the plate. You would have to use pure acetone as the retarder prevents ink from taking to the image until it is completely evaporated. After printing the edition, water is used to strip the plate clean -- ready for another image. My only concern is that silicone does not bond as well to gum as it does to bare aluminium. This could limit the size of an edition, but it is more than adequate for the small editions required at schools.

During the fall of 1997, I have developed a method by which old used plate can be recycled in this waterless process. I have found that the back of the plates actually produce a better image and have taken to using that side. I found that common commercial aluminium from a metal supplier can be used effectively for waterless printing; these much thicker sheets can be reused many times to save money. Look for my paper on this process.

Other substratum

While grained aluminium plates do present one of the better surfaces for this process, I have been able to produce good prints from specially prepared paper plates. Paper plates are difficult to make and would be best manufactured with better control than I could achieve in my studio. While not all paper plates performed perfectly at this time, there seems to be enough success to keep me working in this area because of the cost saving for students.

While regular litho stones can be used in waterless, they have to be first coated with a waterglass solution to protect the surface from the acetic acid in the silicone caulking. Dilute the sodium silicate so that it would produce a good seal on the stone surface. Buff the waterglass with a cloth that is lint free to prevent hardened particles after it dries. The drawing is done on top of the isolation layer with any of the previously mentioned materials. The stone can be grained after the edition is finished.

Another interesting surface is the use of common plywood's. The surface is first sealed with shellac. If a solid image is wanted, it is drawn with water soluble materials. After the silicone is applied and cured, the wood can be carefully abraded to reveal the grain of the species. I have never tried to find the total number of prints the plate may produce, but it should be more than enough.

Glass sheets are another candidates for drawing surfaces. The glass has to be 3/8th to inch thick to prevent breakage. The surface is sandblasted or grained with a small levigator. The new orbital sanders are a promising tool to make the work easier. This technique has been perfected by Littleton Studios in North Carolina. Other printers have learned the method from them.

Acrylic sheets can be grained in the same way but can only be used with water-based drawing materials. Silicone does not adhere to acrylic as well as it does to other substrates, but is a material that would be very interesting to use. There is on the market a special silicone caulking made for the acrylic plastic sign industry, which should be effective for waterless litho, but I have not had the opportunity to get some for testing.

Printing and using a clean sub-plate

Method #1
To make the printing area cleaner, it is possible to produce a subplate covered with silicone which will reject ink. While I have used old aluminium plates at first, common Masonite is much better. At first, it was obvious to have the subplate on the press bed, under the printing plate. Because metal plates in time will stretch in the middle under pressure of the scraper; where the smaller plates are placed, the edges of the subplate will curl in time and will not lay flat on the press bed. Masonite is flexible and does not have this problem. If you have the space, it is much better to establish a rollup island next to the ink slab and press. Take a piece of 1/4" Masonite and cut it slightly larger than your inking table near the press. Use Masonite that has pronounced grain on the back as this will become the upper surface and is necessary to hold the silicone which will be applied to make the subplate. Attach strips of wood around what will be the under side, to keep the subplate from moving while rolling up a plate.

Dilute silicone as if you were going to use it on a plate but use it to seal the Masonite. Let it cure. Next use silicone straight out of the cartridge and put a heavy bead across one end. Using a wide putty knife, spread the silicone as evenly as possible over the entire surface. Work the material well into the groves of the texture for a proper bond. As the silicone picks up broken strand of wood fiber, it becomes contaminated; replace with fresh clean silicone and finish coating the surface.

If the surface is very ridged, it has to be rolled smooth in some way. Take a brayer that is about 6 inches wide and cover the surface with contact vinyl plastic (MacTac); this will help in restoring the roller for normal use. Roll all over the surface and spread the silicone evenly. Set the roller aside and remove the plastic only after the silicone has dried. The subplate surface can now be polished to a smooth finish with a cellulose sponge dampened with water. Let the subplate cure overnight and apply another coat next day or two until all fibers have been covered or eliminated. If your Masonite leaves fibers sticking up, they can be singed by passing the flame from a propane torch lightly over the surface. It is not necessary to have all the Masonite groves filled to produce a perfectly level surface. It is important that there are no high ridges on the surface as this will produce uneven inking of the image. With care the subplate will last a long time and can be replaced inexpensively or recoated if damaged in any way

When the silicone is well cured, it will produce a surface which will not take ink. When used, the actual printing plate can be attached to this subplate, allowing you to roll off the edge of the plate without leaving a layer of ink all around the printing plate. This makes for a cleaner area with less chance of soiling the print, and certainly less messy at cleanup time. Since many of our students use registration pins, these are attached to the press bed, leaving the rolling up of the plate easier as the pins do not get in the way of the roller. This extra step in no way impedes printing.

Since a thick coat of silicone has a sticky feel, it will hold the smooth back side of the metal plate and allow you to roll up and print with no problem. One brand of silicone I used for this purpose held too well to the smooth back of the plate so that it was badly bent when I tried to remove it. I had to wipe down the back of subsequent plates with liquid soap to get the right stickiness. You are now ready to ink the plate.

Method #2
Another solution to make a subplate is to use two of your biggest aluminium plates and secure them to a table so that they leave an area around the biggest plate you use. By coating them with silicone, you get a smoother surface at the cost of two plates. I have used old plates from finished editions which have had the image washed out and blinded with silicone. All damaged silicone surfaces can be fixed by removing ink with a strong solvent, then recoating the surface with silicone.

Method #3
For my own studio, a sheet of plate glass that has been grained and coated with the diluted silicone makes the best subplate of all, as it is perfectly flat. This is placed on a table next to the press. About once a year, I will clean the surface very well with solvent, then apply a thin fresh layer of silicone. This is the best of all subplates that I have made and tried and would recommend it for a working studio, but not for a classroom.

Inks best suited for waterless printing

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 other will need modifiers. Some require so much modifiers that it would be better to choose another ink for printing the edition. Because of the concern that commercial litho inks may not be permanent, my early work was done with inks accepted by the art community. I have now tested a number of available inks and have found Van Son rubber based to be near perfect. They have much stronger pigmentation than some other popular brands. My process works best with the new quick set inks that are common on the market. Inks that were satisfactory are:

*Van Son Rubber-base inks. These stiff high tack ink printed the best right from the can.

*Hanco CS series are made with quick set vehicles and will work quite well. These inks need more modifiers than Van Son. Can be mixed with Van Son.

*Green Drop Ink Company. A waterbased ink made from plastic that becomes waterproof on drying, but can be removed with soap and water. It has no volatile hydrocarbons and is considered none toxic. This new product has great possibilities for artists worried about solvents in the workplace. Unfortunately, this company has ceased operation and inks are no longer available. I have returned to research in this area, with very good success, but the formulation is too complex to explain in this paper. I hope to find a simpler mixture of materials that will produce a modifier that can be added to common printing inks. I have found that about 15% of my present modifier will produce a good printing ink that becomes waterproof on drying, but can be cleaned up with soap and water.

For those who do have a supply of the Green Drop inks, I suggest you use the following techniques. While the Green Drop inks could produce prints on waterless plates, it is not an easy ink to print with. One of their drawbacks was their fast drying on the slab, that caused problems when printing editions all day. The common practice has been to scrap the slab every so often and refresh the ink. In January of 1999, I found that that a modified version of the Green Drop ink produces much better printing results than what the manufacturer supplied. By mixing the Green Drop ink with Van Son or any of the other common oil inks, they are emulsified together. This also reduced the tendency to tint a great deal. To slow the drying on the slab, addition of Golden Acrylic Retarder did the job. I was surprised as to how much retarder could be added without increasing tinting.

Starting with a ratio of about 1:1 of Green Drop ink and Van Son, mix them well together with a spatula. The ratio will make a difference in the characteristics of the ink, much like modifying any ink. Next add the retarder and mix in well. The new ink will still clean up with water, but may require more soap if the ratio of solvent ink is increased. I believe this ink mixture can perform better than either ink system and could become the material of choice for printers, as well as for schools.

Modifiers for inks

If there is uncontrolled tinting, the Van Son ink should be made shorter with the addition of epoxy hardener only, the resin is not used. Magnesium carbonate is also helpful in some inks. Take a very small amount of hardener and work it into a small amount of ink, then add more and more ink to incorporate the hardener into the ink. While most work, I have found regular Lepages epoxy was the best hardener for this purpose; do not use the 5 minute epoxies. If too much hardener has been added and the ink does not want to transfer, use one of the drying vegetable oils such as sunflower, safflower or walnut salad oil. For a less viscous ink I use these oils as modifiers over flash oils and the like. I now modify some inks so that they practically pour off the spatula; this gives me greatest detail in the fine tints and keeps the darks from plugging up. I have also found that the new alkyd gel in a tube, used by painters, make a very good reducer. I like to print on soft smooth papers such as Arches 88 to get the most detail, when having direct plate to paper contact.

Rollers best for waterless

I have developed a three part roller that overcomes 90+% of tinting problems. This roller assembly consists of two smaller diameter rubber rollers (1.5 inch) that contact the plate, with a larger (2.5 inch) metal supply roller the contacts both. The small diameter rollers provide a greater snap because of the sharper angle of the roller to the plate surface. (See appendix of how to make such a roller)

Good synthetic rubber rollers are the best to use. Leather rollers may deposit the ink more even and bring up the lightest tints on the first passes, but they leave tinting on the plate. 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. While it is hard to over-ink, don't, as this process does not release the excess ink as quickly as flooding the plate with water in traditional lithography. Over-inking has to be removed with a sheet of newsprint run through the press.

Because of a very stiff ink and the thickness that results, darkening of the dark areas can be a problem. This does not fill-in permanently on the plate and the image there looks the same as before, but the pressure of the scraper has forced the ink to spread and darken the passage. Use a softer ink to produce the lightest tints and the cleanest dark passages. I have found those papers which are soft and can absorb ink under pressure, give the most accurate impressions. Calendered papers can produce very fine impressions when the pressure is adjusted properly.

Wash up solvents

In the past I use to remove ink from the image with acetone, when a change of color was needed. It depends on the binding vehicle used to grind the ink, but some inks can be removed with alcohol. While it may not take out the ink right to the bare metal, enough is removed to provide a clean printing plate. The residual ink within the grain of the metal act as a printing base and I have never been bothered with it. The other advantage of the alcohol is in the way the ink is removed. By using facial tissue and a liberal amount of alcohol, a tight circular action will strip the ink from the surface as a gummy, tacky residue. By not dissolving the ink, less alcohol is needed to clean a plate than one would with lithotine; acetone acts the same way as alcohol with some inks. Mixtures of the two is possible to nicely clean your particular brand of ink. Try a 1:1 mixture of acetone and wood alcohol. By modifying the commercial ink, you also change its solubility in alcohol or acetone. Another ink remover is acetone with a small amount of ethylene glycol, available in automobile antifreeze. Some of the new citrus type cleaners work well also.

While I have not been able to obtain Isopar, an iso-paraffin product from Esso, I hear it washes out a plate effectively, without damaging the silicone coating. Various grades of Isopars are available but I do not know which works the best.

With the Green Drop/Van Son mixture, wash out from the image can be done with water and a little soap added.

Adding more silicone rubber to the surface

If for some reason the ink starts to adhere to the plate, you may be able to recover the image and save the edition. There could be a number of reasons for the problem and understanding the process can help in determining the remedy. The surface of the plate may not have been clean enough for the silicone to take hold, and in time has started to strip off the contaminated areas. If the plate has a very rough texture and your silicone not heavy enough to bridge the sharp points, this will cause tinting. In each case it is possible to add fresh silicone, as long as there is some silicone still present on the surface of the plate.

If some areas outside the image have not had enough silicone rubber or it has been damaged, those areas should first be cleaned with white gas or lacquer thinner to get rid of all the ink and clean the metal surface. Counter-etching with a strong solution is probably the best remedy but applying silicone rubber without counter-etching may also work. If I want to prevent problems, I will apply a weak solution of waterglass (sodium silicate) to the area first. Next apply silicone, buff the area and cure the rubber. If part of the image is to be deleted, the same procedure can be followed. Waterglass produces a layer of aluminium silicate, a good base for the silicone. To hasten the drying of the silicone, I use a more diluted solution that is made up of camp stove fuel, which evaporates very fast. It can be applied in more than one application to build up a reasonable layer of silicone.

If you want to apply silicone rubber over the entire plate, you must protect the image from the silicone. What is needed is a material that will stick to the clean metal in the image and be rejected by the silicone coating. After the silicone rubber is applied and dried, the protecting layer can be removed to restore the image. For this we can make a special base. First the ink must be removed from the image and made acceptable for a water based material. This is best done with acetone and a retarder, such as the toner developing solution. Washing the surface with strong detergent should improve adhesion of the water-based ink.

While experimenting with the use of water soluble inks, I had decided that this research should be undertaken by some better equipped laboratory than what is in my studio. The research has not been in vain as I found a better method of protecting the image when one requires to recoat the silicone surface. By using water-based blockprinting inks, one has the basic material for the image protector. Some brands of these inks work better than others so I suggest you try more than one. As they may dry too quickly, you will have to add a retarder of some sort. Make sure there is enough binding media in the ink to protect the image. As a retarder, I have used many compounds with success so you should have no problem finding one that works for you. Golden acrylic retarder, glycerin, and ethylene glycol are amongst the best to work with. Add about the amount of retarder to the ink. This gives a thinner ink, but seems to work well enough -- adding pigment is not necessary. The need for and the amount of retarder necessary will depend on the ink you use. My Talens water-based blockprinting inks has worked perfectly without modification.

Use a brayer and roll ink into the cleaned out image. At first the ink will take to the silicone, but as you roll, the ink becomes stiffer and tackier, then starts to be rejected from the surface of the silicone. Because of the retarder, it is possible to get even inking over the entire surface. Keep rolling until the silicone is nearly free of ink. I have found that the heat gun set on low heat will hasten the drying. Since the ink will be still sticky, force air dry it with a heat gun until it doesn't come off on you finger. Now use a Kleenex saturated with odorless paint thinner and remove any unwanted ink that has stuck to the surface. Use water to clean any places that are to be deleted. By applying another layer of silicone, the plate is brought back to service after the ink is removed with water. This is the preferred method of replacing the silicone as the image is better protected from the fresh coat of silicone rejecting material.

Making quick corrections to areas picking up ink

There will be times that for some unknown reason an area of the plate may start to take ink. If these are cleaned with white gas, the surface will be dry in a moment and can be resurfaced with silicone. I think that it is a good idea to apply some sodium silicate until it takes to the surface, then flush with clean water and dry. Prepare some caulking silicone diluted with pure white gas rather than odorless thinner, to produce a fast drying solution. Dilute the silicone much more than for surfacing the plate and store in a tightly closing bottle; I keep mine in the freezer. Apply the deletion fluid with a Q-tip for tight areas, or a facial tissue in the open sections. Buff quickly to an even film and allow to dry for a little while, or force dry with the heat gun. In most cases this will blind the offending area and you can proceed to print the rest of the edition.

Putting the plate away and cleaning up

When you are finished printing or proofing, it is not desirable to wash the ink from the plate. On a number of plates where I removed the ink before storage, the silicone seems to have creeped into the fine image areas and prevented reprinting of the plates. I feel that the ink protects the metal surface from oxidization and it can be easily removed later with acetone or soapy water if using the GD/VS mixture, if it hardens. The non-printing area is covered by silicone which retains its rejection capability if not damaged in any way. I protect the plate between 6 mil polyethylene plastic. This is available in rolls from the local builder supply who sell it for a vapor barrier.

Observations

Waterless lithography is very different than traditional gum/water printing. Less chemistry is required as only a few store bought materials are needed. There is no real need for hard-to-get products such as Gum Arabic, the various acids one may use, the soft cheesecloth or lintless wipes. All the materials I have used are available in town as household or everyday trade products. None are toxic to any extent, and are inexpensive besides. The main advantages over gum plates are:

1/ If toner or water-based materials alone are used for the image, there is no need for vinyl lacquer base with its toxic solvents and strong odor.

2/ Acids are only needed for counter etching and then other commercial products can be very easily obtained.

3/ Timing of the application of etch is not required to produce a stable plate. Over or under etching is not a problem.

4/ Because the carboxyl radical is present only in the ink, while the non-printing areas are covered with silicone, a stable plate is the result. Blinding or filling in is not a problem.

5/ The silicone rubber layer is extremely tough and bonds very well to proper substrata.

6/ Stopping to print for any length of time does not require the plate to be gummed up and later washed. Putting the plate away for later editioning requires no special consideration.

7/ I have found the plates to take considerable abuse before problems arise. This happens mainly because I try to find the limits to the process and subjected the plates to a variety of materials that would normally not be used.

8/ In traditional lithography, when printing color editions, wet ink may sometimes offsets to the non-printing wet areas of the subsequent plate and takes hold. Silicone rejects the ink, preventing this problem.

9/ I have found that the lightest tints can be better reproduced with the waterless process rather than gum/water plates. Because there is no acid to erode the image, the light tints remain on the plate.

10/ Hot air from a paint-stripping gun can be used to quickly dry and cure the various materials used.

11/ Because the process is waterless, the paper stays dry and dimensionally stable. Paper registration is more assured and colors tend to print clean and brighter.

Disadvantages

1/ As in most cases, improvements are not without some sacrifice and this process is no exception. While the technique has problems, they are of a different nature than gum/water lithography and have to be overcome. The most important concern is the loss of making changes to the plate; by adding or changing the character of the image. Because the silicone layer holds so tenaciously to the metal, it is very difficult to remove the materials to resensitize an area for changes. The use of ammonium bifluoride solution or the commercial magnesium wheel cleaners may be less desirable, but a very effective stripping agent.

2/ Deletions are very simple to make. Just take off the image with solvent to remove the ink, then apply some silicone rubber and let it dry. The strong bond of silicone to the aluminium, while producing a superior plate, makes changes to the image difficult.

3/ Buffing down of the silicone rubber has to be very smooth so that lines do not appear during printing.

4/ The need to use acetone instead of a cheaper hydrocarbon such as Varsol can make wash out more expensive. If you are accustomed to use commercial lithotine, then the cost is about the same or less. Acetone with other additives removes ink in a peculiar way by not dissolving it, but by lifting it very clean off the surface. If you start to use the GD/VS ink mixture, then solvents are not a problem.

5/ As in most cases, when a plate losses an image, there is not much that can be done to bring it back. While more forgiving than traditional lithography, the plate can become unprintable if one is careless with processing or use of solvents. As long as the silicone rubber layer is intact, the plate should be able to be brought back to a serviceable state.

Conclusions

Waterless lithography has been a dream of some commercial offset printers as they saw advantages to get rid of the fountain solution that used chromate's or isopropyl alcohol. The ink water balance is a factor, which makes the difference between an excellent print and one that is just passable. Humidity and other factors make printing of traditional lithography as much an art as it is a craft, as the printer bring his or her experience into the editioning. A stable plate is the goal of the printer and any technique that provides it, should be accepted by the profession.

I have been asked, if a water plate is printing well, why convert it to a waterless one? If the printer is skilled enough to produce perfect plates every time, then there is no need for change. But it takes many years of experience to become a master printer who can control all nature of lithographic techniques. Maybe in waterless lithography, there is more forgiveness and so editioning can be much less of a problem. Only time can tell if this process will have any effect on the printing of fine art editions.

I developed the basic process in June 1990 without the input of anyone else and have been improving it since. It is capable of printing large editions as has been proven by other printers. I am wholly responsible for this process, which has become the basis of techniques promoted by others. It is unrelated to the commercial Toray process that uses photo negatives or positives. I have invented the 3-part roller that makes waterless litho much easier to print. That piece of equipment is also being manufactured by others; there is even an attempt by them at patenting the innovation.

Glossary

· Acetic acid: An organic acid found in vinegar. A stronger form is released by the silicone rubber on curing. Because of the small amount released when used on a plate, there is little health risk involved.

· Acetone: A keytone that is used as a strong solvent. It is more dangerous because of its low flash point rather than inhalation, which allow 1,000 ppm3. It mixes with water and most solvents. Available from hardware and paint stores.

· Ammonium bifluoride: A compound containing ammonium fluoride with a hydrogen fluoride molecule. Because of the fluoride present, great care should be taken in handling this material.

· Isopropyl Alcohol: An industrial alcohol used by the commercial printing industry in fountain solutions. Toxic level is 400 ppm3.

· Lithotine: A turpentine substitute consisting of aliphatic hydrocarbons, pine oil and gum ester or castor oil. Because of the hydrocarbons, the toxic level is 100 ppm3.

· Methylene chloride: A low boiling point chlorinated hydrocarbon. Avoid prolonged exposure to vapor. Used in the screen printing industry.

· Odorless Paint Thinner: A hydrocarbon that has been modified to remove the smell of solvent by eliminating the aromatic compounds. This changes the liquid so that is has less of an effect on the silicone rubber and some toner images, than one gets from ordinary paint thinners.

· Silicon: The 14th element on the periodic table, it comprises 25.7% of the earth's crust and the second most abundant element in the universe. Never found free in nature, it can be combined to form many different types of materials.

· Silicone: Silicones are important products of silicon. Technology can produce polymeric products that range from liquids to glass-like solids. Caulking compounds are rubber like materials that are useful in the waterless process. Available in hardwares and paint stores.

· Varsol: A high flash point hydrocarbon originally known as Stoddard solution.

· Stoddard solvent. Its toxicity level is given as 100 ppm3. Sold as a paint thinner and cleaning solvent, it has a number of other uses.

· Vinyl Printing Base: This product will vary from one manufacturer to another but they all seem to contain aromatic hydrocarbons and keytones as solvents for the vinyl plastic. Considered a health hazard.

· White Gas: An aliphatic hydrocarbon with a very low flash point. Sold as camp stove fuel in sporting stores and hardware's.

 

Materials List and Formula For Various Solutions Used In This Waterless Process
- that are not available in a normal lithograph workshop

 

Drawing materials

· Staedtler Omnichrom 108-9 pencil- a black water soluble pencil unaffected by hydrocarbons. Sold in drafting supplies and some art stores. Used for crayon drawing effects.

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

· Toner - Dry copier toner washes used for reticulated textures -- using both water or solvent washes. Compressed toner can give charcoal effects. See my toner paper.

· Future drawing fluid -- Common Future Acrylic Floor Polish, diluted with water and colored with Sumi ink or colorant, makes a waterproof image. Used for pen lines and solid flats where water-soluble materials cannot be used, such as reversals.

Setting Fluid

· White gas -- Common campstove fuel from sport supplier is used to set toner images sometimes. If type A toners are used, the white gas is used as a carrier by adding 5-10% acetone or lacquer thinner to help bond the toner to the plate. Test the amount of the stronger solvent needed for your toner. Some toner require a slightly longer exposure to the solvent, so the addition of common paint thinner will slow the evaporation.

Silicone coating

· Caulking silicone -- Common clear caulking silicone in a cartridge is diluted with odorless paint thinner to the consistency of a light maple syrup. This is done in a small polyethylene container with a thigh cover so the container can be reclaimed, or empty 4 oz. baby food jars. Add solvent a little at a time until the right consistency. Dow-Corning clear caulking silicone is the best I have found, but seems to be no longer available. Instead, I have been using their #999-A, a professional product that is available through contractors building suppliers.

Wash out solution (Developer)

· Acetone -- Common acetone is used to wash out toner and Future polish images. To retard the evaporation of acetone, diacetone alcohol is use by adding about 5-10% to the developer. Diacetone alcohol is used in the screen printing industry as an ink reducer. My supply is from Colonial Printing Ink Corp.; sold as ST-212 reducer. Other retarders work. I have tried Butyl Carbitol and Ethylene Glycol, but prefer the Diacetone Alcohol.

· Citra-solve - a commercial cleaner and degreaser that seems to work well on type B toners only. Can be mixed with acetone to make an effective developer. Use soap and water for the final cleanup.

Ink Stripper

· Acetone/alcohol -- a 1:1 mixture of the solvents lifts ink without dissolving it. This takes less of the solution to clean a plate for changing colors. While it may seem slower than dissolving the ink with solvents or straight acetone, it is very effective and safe. Modified inks may need a different proportion of each solvent. Other additive may be used as well. Use Kleenex or paper towel for ink removal.

Soapy water -- When using GD/VS ink mixture, plain soap and water will remove the ink from the plate.

Image Protector

· A waterbased relief printing ink with about 25% of a retarder added. This is rolled on with a small brayer.

Silicone Stripper

· Ammonium bifluoride -- Also known as ammonium hydrogen fluoride. Because it contains hydrofluoric acid in the compound, a weak solution of this will strip the thin silicone layer effectively. Place a teaspoon of the chemical in a plastic container and about 8 ounces of water to dissolve it. Add some hydrochloric acid to improve chemical action. Next, add a strong liquid dye and stir. Alcohol or acetone can be added as a wetting agent if the stripper is not to be used on inked images; leave these out if it is to be used over images. If ammonium bifluoride is not available, use ammonium fluoride to which a bit more of hydrochloric acid can be added to activate the stripper. Ammonium bifluoride is used by stained glass workers to etch glass and should be available from them, rather than a chemical supplier. Use these chemicals with great caution.

Commercial magnesium wheel cleaners -- 'Eagle One Etching Mag Cleaner' and 'Mothers' Wheel Mist' are a couple of products that contain a small amount of hydrofluoric acid, along with some phosphoric acid. Dilute and put into a plastic bottle as you don't want to inhale any of the mist. Chemical analysis has shown that under 1% of the solution is HF. When diluted to an effective stripping solution, the percentage will be around .35%.

Odorless Paint Thinner

· Odorless thinners are sold in art stores as well as most paint and hardware stores. Use the cheaper paint store variety, but some will not work as they can harm your plate. Remember that it is still a hydrocarbon and should be used with care.

Silicone Caulking

· Dow-Corning clear silicone caulking in cartridges is the best material to use. In the small amounts used, the acetic acid used in manufacture is of little concern. With the disappearance of the Dow-Corning consumer material, other suppliers will have to be used. Ask for DC 999-A at a building contractors supply house. General Electric Silicone II is a good material for caulking windows, but rather a poor silicone for this process.

Dry Copier Toners

· Toners can be of various manufactures and should be tested to learn of their characteristics.

· Some toners are not effected by hydrocarbons (type A), while the greater majority are (type B). Since these designations are my own for classifying the materials you may encounter, you will have to test the toner for yourself. All toner are usable, only that you will have to know their limitations. You should be able to pick up discarded toners from a laser cartridge refurbisher or a copy centre. Toner is basically plastics, the amount of acrylic, styrenes or other polymers is the manufacturers secret. See my toner paper for more information.

Applicators

· Soft urethane sponges are the best to spread the silicone over the plate surface. They should be cut into small 1.5 inch squares. A much larger one is used to back the facial tissue used to buff the silicone to a tight film. Common facial tissue are the best and cheapest to this purpose. The foam sponge material can be purchased from a department store where it is sold for upholstery. You should be able to obtain scraps from an upholstery workshop.

POINTS TO REMEMBER

1/ Silicone caulking products may change without notice. While most work, the change may be enough as to cause problems. I have used many brands but clearly found Dow-Corning better than most. Dow Corning produces a cartridge that has a screw in nozzle that makes it easy to dispense a small amount and close it for the next time. It is also marketed under others labels. Other cartridges need to have the nozzle cut which prevents tight closing and subsequent drying in the tube. By using a Marr #2 electrical connector, the opened tip can be effectively sealed. Keep the silicone in your freezer for a longer shelf life, as it deteriorates in time.

2/ Make sure the tops of the aluminium grain is covered by silicone rubber, or tinting can be a problem. If coarse plates are used, two or more coats may be needed. For the finest tints, use the smoothest grained plates you can acquire. A slightly grained surface is better than a glass smooth surface to bond the silicone to the metal. The slightly roughened back of plates make the best substrates for this process.

3/ Hydrocarbons harm the silicone coating and allow the ink to stick to the plate. Acetone and alcohol's are better to remove the ink. Soapy water safest of all for use on the GD/VS ink mixture.

4/ There is no need for a vinyl printing base as the metal will absorb the ink molecules in time. While in gum/water lithography the strongest part of the plate is in the vinyl base and grease image, in waterless the opposite is true. Because the silicone bonds so well to the metal surface, it cannot be displaced, and it cannot move into the image areas.

5/ There are 3 possible ways to use this process:

I- Directly with a toner or water based imaging materials.
II- Directly as a grease image or conversion of a proofed grease plate.
III- Directly as a photo image or conversion of a proofed photo plate.

6/ It is extremely hard to lose an image. As long as a thin layer of silicone is present on the metal, an ink-rejecting surface can be produced with more silicone rubber.

7/ An effective drawing ink can be made from Future Acrylic Floor polish by adding a coloring agent such as lampblack in cheap Sumi ink. This fluid can be used also with brushes to cover large solid printing areas. Since only a thin layer is needed to protect the plate surface, it can be diluted to just the right consistency. Acetone can be used for development. A simpler glue based ink can be made with dextrin or other glues, and Sumi for coloring. The advantage is that it can be developed with plain water.

8/ White lines and other changes can be scratched into solid areas, just like in stone work. The silicone will protect the scratched area from taking ink.

BIBLIOGRAPHY
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

Three Part Roller for Waterless Lithography

 

Developed by Nik Semenoff during 1992 & 93

 

 

 

 

Here are pictures of the three part roller that I have developed to make waterless lithography even easier to print. I was going to patent the roller but had decided to just make the design available to all printmakers. This roller is made from nitrile rubber rollers that have been ground down to 1.5 inches in diameter. The steel tube that acts as a supply roller is made of DOM steel .125 inches in thickness, 2.5 inches in diameter and 15 inches long. These are not important dimensions as other prototypes have been quite different and all have worked.

 

 

 

The support assembly is made from wood with one end block left free for taking it apart. The end blocks are made together so that the holes line up perfectly. The center support is made from two pieces of wood that is grooved in the middle before they are glued together. While this roller has had the support lathed to close tolerances, other prototypes used planed supports. Plane the centre support until it is nearly a cylinder and cut to length, making sure the ends are square. Leave about .125 inches clearance between the steel roller and the end blocks by making the inner support a bit longer. A threaded rod is used to hold the unit together with the nuts at both ends secured with epoxy to the wooden handles. A third nut is used to keep the main assembly together when the rollers are taken out for cleaning. This nut is recessed into the end of the support so that the removable end block fits nicely. Glue can be used to secure these three pieces. In the ones I manufacture, the end block are not glued to the inner support.

To make the end blocks, measure the diameter of the rubber and steel rollers you intend on using. With a good compass, draw the inside and outside diameters of the steel roller on a piece of bond paper. With the compass set to the diameter of the smaller rollers, draw a circle touching the larger one. Space the next small roller far enough apart to give the unit some stability. Next, draw the diameter of the end shafts of the small rollers. Indicate the surface of the plate by drawing a line touching the bottom of the smaller rollers. Leaving between .125 and .25 inch between the shaft and the edge of what will be the bottom of the end block, draw a line parallel to the plate surface. This space may vary with the diameter of your rubber rollers. This line will become an important line of reference later. Now complete the outside outline of the end blocks. This design has square ends that allow me to put the roller on its side or top while printing or for storage.

The diameter of the inner support is slightly less than the inside diameter of the steel roller, but placed in such a way that the all rollers are in contact when rolling up, yet lets the steel roller fall away from the rubber ones during storage. This prevents flat spots on the rubber rollers. To get the proper placement, draw in the diameter of the support so that it allows for some room around the top and bottom of the inside steel tube. This is usually right on the centre point or just a little above. This hole will become the placement of the handles. Don't make the centre support too small or you will have a weak system.

From this template, transpose the centre points of the places where the hole will be drilled, to one of the pieces of hardwood for your end blocks, taking care that the reference bottom line is along one end of the long grain of the wood. Clamp the two small pieces of hard wood together with the bottom edges sitting on a flat surface, then drill the three holes with the appropriate size drills. The holes for the rollers should not be too tight. Once the two end blocks are drilled, the clamps are removed.

Assemble the main units, then seal the surfaces with lacquer. Glue can be used to keep the central support and one end block together. The third nut is recessed into the inner support and tightened with the nut on the solid handle which goes through the support. Put the rollers in their place and fit the free end block to the main unit. Before tightening the free end block with the screw-on-handle, place the roller on your ink slab to make sure the small rollers are flat on the surface -- then tighten the handle. If properly made, the roller moves freely as the steel roller revolves on top of the rubber ones by pressure from gravity. When the assembly is turned upside down, the steel roller should separate cleanly from the others. The other nice thing about this roller is that you will never get blisters again, and it works perfectly for traditional lithography!

The reason for this design is that the smaller rollers contacting the plate will lift the ink tints off the surface because of the greater upward lift or snap for any given forward or backward speed. Larger rollers have a lesser angle when orientated to the plate surface and not as fast a snap. The total circumference of all three rollers turns out to be greater than for the average rubber roller, so has enough ink to cover much more of a plate. Inking is also more even because the pattern is not repeated with the different diameter rollers. I have produced one model with different size rubber rollers to make the pattern even more ambiguous. I don't think there is enough difference to promote it other than you could easily use different size rollers if that was available to you.

Cleaning is very simple. Just add cleaning fluid to the scraped ink slab and pass the roller back and forth until the ink is dissolved. Then pass the roller over newspapers to get the rest of the ink off. If the ink from the newspaper dirties the rollers, clean newsprint can be used, or blanket wash will leave the surface clean for the next ink. The ability to take apart the unit is just to give it a very good cleaning every so often.

I see no reason to use any other material than wood for making the support unit. Wood bearing have been used in the past with great success and should last for years if not abused. Wood is light and easy to work with, keeping cost down. For my manufactured systems, I have used soft metal sleeves as bearings. Rollers may be more of a problem. I found old wringer washing machine rollers very good except for their shorter length. Since they may be old and not in good shape, most of the outer portions will be ground off on a lathe to reveal a fresh inner surface. I have also used inking rollers from a Multilith #1250 machine. These are 11 inch long and much smaller in diameter than I would like. There are two reciprocating rollers about 2 3/4 inches in diameter on each machine that can be used in place of the steel tube. These rollers can be taken apart to reveal a nice metal tube that is coated with rubber. These rollers should be available from discarded machines.

My very first attempt (in 1992) to build a prototype used rollers from a surplus supply. After careful construction and assembly, I was dismayed to find that these rollers were made of high silicone content as ink would not take to them! By temporarily covering them with MacTac, I proved the concept and started looking for pure rubber rollers. The designs progressed and I decided in 1993 on the simpler inner support system. I now commercially produce rollers 15 inches long, made from LHB (HT) Nitrile to meet requests by printmakers for a good working system. I gained a lot of experience in producing the 12 prototypes while doing my research and know just where close or loose tolerances are required. Good luck and I hope your rollers works as well as mine. The pictures of the roller are of the system I manufacture for sale, but if you have good construction skills and have access to lathes etc., then maybe you can produce a roller that will meet your needs. If you need more information on making your roller, feel free to contact me.

Recent Developments

In the spring of 1996, I produced a system that allows me to print my editions as offset by using my hand transfer press. I call the system linear offset because the motion is on a flat plane rather that using any a cylinder to hold the blanket. I have found the following many advantages to this method:

· Much less pressure is required for printing even the hardest and more textured rag papers.

· There are no salt and pepper areas because the soft blanket deposits ink in the hollows.

· Flats are always flawless and even in color.

· Registration is perfect.

· Colors are rich and bright even with one pass through the press because a sufficient amount of ink can be transferred from the plate and to the blanket, then to the paper.

I now print all editions with my linear offset attachment. It is easy to remove by the way it is secured to the present press bed; this allows for ordinary transfer printing. A Lexan tympan is hinged to a inch aluminium plate in a way to make removal easy for cleaning. An offset blanket is bonded to the tympan and all is kept in registration by the precision hinges and tapered registration pins placed at the foot of the aluminium plate. With this four-point registration system, perfect color registration is assured. Considering I ink up my plates on a subplate that is close to the press, printing is a continuous process. As I have a motorized press, I ink up my plate while the sheet of paper is being printed; no time is lost. Since I started to use the system, I have not lost one sheet of paper in an edition due to variation of color or insufficient inking.

Here are some quick sketches of the linear offset.

Permission to photocopy this document is given to help get dangerous material out of our studios. Publication without the consent of the author is prohibited as I would want the latest information published. Contact me for publication.

Nik Semenoff, Artist-in-Residence,
Department of Art and Art History,
University of Saskatchewan,
Saskatoon, Saskatchewan, Canada. S7N 0W0

e-mail address <semenoff@sask.usask.ca> web page <http://duke.sask.ca/~semenoff/>

 Updated October, 1999