USING DRY COPIER TONERS IN INTAGLIO AND
ELECTRO-ETCHING OF METAL PLATES
Published in LEONARDO, Vol. 24, No. 4, 1991 - received May 1989
Nik Semenoff (artist and teacher), Artist-in-residence with the Department of Art and Art History, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Christine Christos (artist and teacher)
Abstract-- 1/ The authors describe a method of achieving wash effects on intaglio plates with dry copier toners bonded to mylar, using photo-sensitized intaglio plates. This techniques grew out of Semenoff's previous work with toners for use in lithography (LEONARDO, Vol. 20, No1, PP 71-77, 1987).
2/ A concept of removing metal by electric current rather than acids. This method retains more of the fine detail produced by toner images.
Engraving and etching are the second oldest printmaking process known to artists. Having been started by goldsmiths and armor engravers as a method of recording their work, the technique of filling incised lines with ink and embossing them on damp paper, has become an important graphic media in the fine arts, since the fifteenth century.
In the early prints, intaglio was devoted only to line, with plastic form and textures depicted by the direction and thickness of line, rather than the use of tones. With the acceptance of acid etching in the seventeenth century, a freer type of image was produced by the artist. Later, with the advent of mezzotint and aquatint, the artist was given the luxury of producing variable tones on the plate. These tonal passages were achieved through laborious methods and a great degree of control on the part of the artist and printer. Loose wash effects, similar to those produced in lithography with grease tusche, was simply not possible for the intaglio printmaker.
In 1985, N. Semenoff began to use dry copier toners to produce exciting washes on lithographic plates. Toners allowed the artist the ability to change the wash image with no fear of leaving a ghost of the previous drawing. An article published in LEONARDO, described the technique as used in lithography. It was suggested in the article that toners could be used to produce intaglio plates by applying it to mylar for use in the exposure of photosensitized intaglio plates. This technique was used by the printmaking technician at the University of Saskatchewan, Christine Christos, who got excellent results; even the lightest tints were reproduced. Because of the cost and general availability of photosensitized intaglio plates, Semenoff devoted his time trying to develop a more direct method of using toners for etching. It has become apparent that as long as photosensitized plates are available to printmakers, it is the best and surest method of using toners in intaglio images. Semenoff has since restricted research on the direct use of toners on intaglio plates because of the superior results obtained on photosensitized intaglio plates. In this collaboration, Semenoff had developed the original concept and has done the research into the use of toners in three major printmaking media, lithography, intaglio and screen-printing. Christine Christo's was the artist/printmaker who did the work on photosensitized intaglio plates and perfected its use in the studio.
DRY COPIER TONERS
Toner copiers have been part of our experience since the mid-sixties with the development of the Xerox machines. Recently, there have been a number of other manufactures that have developed their own version of the electrostatic copier, each with their own formulation of toner. While the toner for use in lithography required certain characteristics, those for etching need not be as stringent when the image is to be put on Mylar for exposure to photosensitized intaglio plates. Our basic toners have been Xerox 9400 and 9500, which are readily obtainable from photocopying firms. Some of the large production machines remove some toner from the charged cylinder, collecting this unused excess for disposal. Most firms would gladly give artists this material because to them it is now nothing more than refuse, but a valuable resource to the printmaker. While having different characteristics to fresh toner, it can be used for this process.
MAKING UP THE TUSCHE WASH
Water is the standard and most used media for use in tusche washes. Since toner powders are made of extremely fine plastics, wetting them with plain water is very difficult. If a wetting agent is first added to the water, the task is made very simple. Among the better dispersants are photographic wetting agents such as Kodak Photo-Flo, or any of the new dishwasher rinse liquids and some of the cheaper liquid detergents. Some of the detergents can produce a considerable amount of foam, which could be useful to obtain particularly interesting textures. Since a very small amount of wetting agent is required to disperse the toner, varying the amount will affect the texture of the wash. Select those that do not affect bonding of the toner.
Mix your basic toner tusche by filling a 4-6 oz. wide-mouthed bottle about 1/4 full of tap water. If the toner mixture is to be kept around for some period of time, it might be wise to add some antifungal compound such as Dettol to prevent the growth of a mold, which the toner and dispersant seems to promote. Add to the water a few drops of wetting agent; the quantity will effect the texture of the wash so experimentation is in order. To the liquid now add toner until the bottle is about 3/4 full. It is just a matter of closing the container and shaking the mixture until the toner has all been moistened. If a thicker mixture is required, add more toner and stir it in with a palette knife. This will become your basic supply for washes as a little can be diluted in a saucer for use on a project. If the supply in the container should dry up for any reason, it a simple matter of lifting out toner with a wet brush as if it was a cake of tempera paint.
IMAGES ON MYLAR FOR LIGHT SENSITIVE PLATES
Photographic images have become standard among modern fine art printmakers. Commercial presensitized photoengraving plates used for production of letterpress half-tone and line drawings are used with positive transparencies to produce images on intaglio plates. While the most often used images have been generated by camera using high contrast photographic negatives, it is possible to make a drawing with opaque materials on clear plastic. Ordinary grease tusche on mylar is not opaque enough to give reasonable control over the exposure of the photosensitized intaglio plate. Areas which appear dense when viewed against a white background are found to be gray when seen over a light table. Toners on the other hand, form opaque images even in the light tints, and are satisfactory for use on photosensitized intaglio plates.
APPLYING TONER TO MYLAR
The toner wash is applied to clear mylar in any manner suitable for the image. Because the toner tends to be granular, it produces a different kind of wash than grease tusche or watercolors. This characteristic is important as it gives the image a definite grain that is important to printmaking. Other materials such as alcohol can be added to produce textures, as long as they do not effect the bonding of the toner particles to the Mylar.
Most etchings have relied on line for much of their charm and it is also possible to include these on a mylar drawing. Pen lines produced with good opaque ink is probably the simplest technique. The mechanical drawing pens of the Rapidograph design come with very fine points and are well suited for this purpose. There are inks such as Koh-I-Noor Rapidraw for film which are made especially for use on plastic and should be used. Some of the Oriental Sumi type inks will bond well enough to mylar, and because of their pigmentation, produce very good line drawings. If the line is to be extremely fine and is separated from the wash image, then the plastic may be scratched with a sharp point and the line filled with India ink. After the ink dries, the surface is polished with a soft cloth to remove the ink from the smooth surface. These fine lines should be opaque enough to hold back the light on a photo-sensitized intaglio plate.
USING ADHESIVES TO BOND THE TONER ON MYLAR
Some artists prefer to produce images with a greater degree of brush control than that produced by the natural reticulation of toner. When photosensitized plates are used and the drawing is put on Mylar, it is a simple matter to bond the toner with any material that will stick to the mylar. Semenoff has found that a simple solution of cellulose glue and a small amount of wetting agent is perfect for the job. Methyl cellulose glue is available in a refined form in art stores and as a cheaper product for wallpapers in paint stores. The advantage of using cellulose paste is in the amount of bulk it gains when wet. On drying, cellulose will produce a thinner and flatter film to nearly eliminate the actual impasto without destroying any of the brush effects. This allows the toner particles to come into closer contact with the sensitized coating to produce a sharper image. Being water soluble, it allows for removal of the drawing if the artist is not satisfied with the results. Scratching off parts with an orange stick helps in sharpening up edges if need be.
If the artist wishes to have a more water resistant adhesive, then there are a number of options available to him or her. While ordinary acrylic medium is usable even with its milky nature, we would recommend the clearer acrylic varnishes which are water miscible. Another group of materials which works perfectly well are the household acrylic and vinyl floor polishes.
These are waterproof, but can be removed with ammonia solutions. To get exciting reticulation effects, dilute the floor polish with more water.
DIRECT APPLICATION OF TONER TO METAL PLATES
Presensitized photoengraving plates are expensive and out of the reach of many artists. For this reason, Semenoff had worked on a more direct use of toners on metal plates. There are two methods of working directly on plates, one producing a positive image, the other a negative one. To produce a positive image, it requires the application of a resist coating over the toner.
Many materials were tried but shellac seems to have the best possibilities. After the toner image has been set on the plate with heat, diluted orange shellac is flowed over the surface to produce a very thin coating. The best material is an orange shellac flakes that is made up into solution by suspending them, within a nylon stocking, in wood alcohol. After removing the stocking, let the solution stand until there is a definite separation between the wax containing portion at the bottom, and the purer shellac on top. Remove the shellac carefully with a poultry baster, leaving the unwanted wax portion. It would be advantages to dye the shellac for which any alcohol soluble dye should work. I use Erosin red dye to just give it color.
Dilute the shellac with wood alcohol so that not too thick a coating is produced. You will have to experiment with this as it is hard to explain the right amount. Use a soft brush to flow the shellac over the surface, starting at one edge. Let the alcohol evaporate before putting the plate on a hot plate for curing. If Shellac is heated above 150 degrees centigrade, it changes from a thermoplastic to a hard, horn like material that can resist mordants very well. Heating takes some time for the necessary change to take place.
Remove the toner image with common turpentine and a short bristle brush like those used stenciling. If the shellac was dyed, you should be able to see the mask left after the removal of the toner.
Etching is best done with electro-etching as the fine detail can be destroyed with strong acids. Selective blocking out of certain mid-tone tints will help retain the tonal relationships of the original drawing. Because electro-etching will break through the smallest opening, it is advisable to block out any area that is to print white. After electro-etching, the coating can be removed by applying a solution of acetone and an alkali, such as sodium hydroxide.
TONER AS A RESIST TO PRODUCE A NEGATIVE IMAGE
The simplest approach in the use of toner for etching is to apply the toner wash in a manner that it will become the resist in the etching process. This is a normal procedure in etching and should not be too difficult to handle for most artists. The toner image is set by heat for best results. Block-out resist is applied to the plate where needed and the metal is etched in your favorite mordant or by electro-etching. Negative toner images tend to appear much darker in print than what they did in the drawing. Because of the very fine characteristics of toner, the fine particles may be etched away as they are under-cut by the acids. Electro-etching is probably one of the best methods of doing away with this problem
Electro-etching is just the opposite of electro-plating, which has been practiced in industry for many years. Although not known to be used by etchers, this process has been of some interest to goldsmiths who are well acquainted with plating and the use of electrical currents. While plating requires expensive solutions which are usually very poisonous because of the use of cyanide, electro-etching needs only the simplest of salts or acids to do the job. Even the low voltage and current used for etching the average plate are not in any way a hazard to health. Small quantities of harmless hydrogen and oxygen are given off and are not a threat at anytime.
Another advantage of the electrical method is in the type of line the process leaves. While acids tend to act in all directions leading to undercutting of tints, electro-etching will leave a line with a depression more like a "V" or "U" rather than an "O". Whereas acid etching tends to heat and over-etch areas with dark tints, electro-etching works in the opposite way. Another advantage is the cost of materials and equipment. Acids are expensive and dangerous to handle. Fume hoods should be used to remove the noxious gasses and safety methods such as splash sinks should be incorporated with their use. While it may be more expensive to build a good power supply with infinite controls, the electrolyte used as an etch bath is not depleted in any way and the inexpensive solution can be used for a very long time. Because there is no acid to become weaker with use, the times for etching the plate can be better controlled through varying the voltage at the power supply. The energy for etching does not come from the acid but from the electrical supply.
ETCHING THE PLATE
For the etcher who does not feel like acquiring a power supply with infinite voltage controls and amperage meters, a small 6 volt motorcycle battery will be adequate. Current can be controlled by the size of anode and may be judged by the amount of gas being liberated at the poles. The saturation level of the electrolyte can also be used to control the amount of current going through the solution. A simple battery charger would be needed to keep the battery at peak performance.
The better supply would be one using power from the mains and capable of producing 10 amps or more of current. Meters for showing voltage and amperage would be desirable, if better control of the process is envisioned. Since there are many ways of accomplishing this, help from a person acquainted with electronics could prevent problems in construction. A gold plating unit from a jewellery supply house could also be utilized.
For etching to take place the plate is attached to the positive pole of a battery or power supply. A plastic tray is used to hold the electrolyte. The anode or negative pole is best made from stainless steel to prevent rust that is inevitable with the use of corrosive chemicals. A large grid-like anode which consists of a chrome plated rack from an oven works very well. This is held by legs about 1/2 inch above the plate to be etched. This will etch the plate over the entire surface but not as evenly as one would like. Because of the laws of physics, the edges of images will be bitten deeper than the areas towards the center. This is just the opposite to the action of acid. Line etching has no such effect and works perfectly. A smaller movable plate somewhat like a pancake flipper is effective if one wants to control the activity in any area. Care should be taken that this anode does not touch the plate as the heavy current would damage the surface and could also burn out an unprotected power supply. Insulating material can be secured to the edges of this smaller anode, to prevent short circuits.
Depending on the size of plate and the total area exposed to the electrolyte, you will have to experiment as to the type of current supply needed. While voltage is the driving force of the process, amperage or current is what actually does the work. Experience has shown that voltages in the range of 2-6 volts are all that are required or desirable in working with average size plates. The higher voltage is used to quickly remove large amounts of metal, the smaller voltage is then applied to produce a fine textured surface in the etched area, that can take the place of aquatinting in some cases. Amperage or current is in the 5-10 amp range. Larger plates would require more current for efficient etching. Smaller power supplies only mean longer time in the bath. Three minutes for the first etch seems to be the average. Weaker currents produce sharper detail and should be used when ever possible. In any case, voltages and current should be kept down to prevent the formation of oxygen bubbles on the image, which will produce broken lines much in the same way as does nitric acid. As the etching takes place, you will notice that the current will began to fall by about 30% from the initial reading; this is caused by the bubbles acting as an insulator in the grooves of the plate. Gentle shaking of the plate will help to increase the current flow.
There are three methods to control the current through the electrolyte. The most obvious is to control the voltage by means of a variable transformer (Variac), or by tapped transformer, or by a variable resistor in series with the current. These are standard methods and information on them can be obtained in libraries and beyond the scope of this paper. The second method is to vary the size of the anode. Varying the distance between anode and plate also has a great effect on the current. The third method is to control the amount of chemical put into the water to form the electrolyte. While some chemicals are very active as an etching compound and will work well with minute quantities, others are not so reactive. By varying the amount of chemical in the water, current can be controlled to some extent. Common chemicals which work very well are table salt or dilute sulfuric acid. The range of acidity is 2 - 3.5 pH for an average plate. Copper or Zinc salts work well with their respective metals.
Where solid areas of metal are etched away, it is a good idea to lay down an aquatint to make sure that enough ink will be held to print a dense image. While in some instances the micro texture left after etching will hold ink for light and mid range tints, the fine grain can be wiped smooth in the darker areas, if a large edition is planned. To keep all the delicate areas in proper relation, aquatinting should not take place until after a first etch. This will prevent rosin from falling on to the very fine points and closing them off from any etching action. By using standard aquatinting techniques one can greatly improve the tonal relationships in the washes. This extra step is not necessary in lithography as the toner washes print exactly as seen; unfortunately the nature of intaglio does not allow this.
CHRISTOS METHOD OF WORKING
Because of Christo's experience and general method of etching, she has chosen to produce work with the simpler photo-etching technique and acid etch. She uses large plates to produce wash-like images combined with screen printing. The basic image is drawn on mylar with toners and other opaque materials, the toner image then set with white gas. The mylar is exposed onto a photo-sensitized intaglio plate in a good vacuum frame for five minutes, after which it is developed for five minutes in blue developer and washed with warm to hot water sprayed on with a hose. Mordant is 1:12 nitric acid in water and is used always for her etching. After development, the plate is given a "shock" stage of one minute in the etching bath. After that the plate is removed from the acid bath, rinsed with water, and dried. Spray aquatint is preferred, using a suitable fresh black lacquer or enamel spray bomb. Do not spray directly on the plate but let the droplets fall onto the horizontal plate as the bomb is waved over the necessary areas.
The first etch is for 12 minutes for all delicate areas. After rinsing and drying the plate, block out the delicate areas with asphaltum and let it dry. Another coat of spray aquatint is applied as before and allowed to dry. The plate is now given another 12 minutes in the acid bath to etch the gray areas. Rinsing and drying the plate is again done before blocking out the gray areas with asphaltum. A third coat of spray aquatint is applied and the plate etched for another 12 minutes to arrive at the middle gray tints. For the dark areas, the process is repeated again by blocking out and applying more aquatint. To get the solid blacks, repeat the process for the fifth time, blocking out and applying aquatint.
The etched plate is then cleaned first with Varsol to remove the asphaltum and then by adding a small amount of lacquer thinner, the spray aquatint can be taken off. Be careful in applying the lacquer thinner at this time as it will remove the blue coating on the surface, which should be left intact until proofing of the image is complete. Because the blue coating will likely break down if a large edition is to be printed, it would be wise to remove it before editioning begins.
PERSONAL STATEMENT OF CHRISTINE CHRISTOS
"When using the Xerox toner on the clear plastic Mylar I experience freedom and flexibility that is inherent in the process. The freedom and flexibility start at the stage of the hand drawn and painted toner image. Here, I can scratch into the surface of the image, add or delete forms, or even make a collage with other toner image transparencies. By using sandpaper on the clear Mylar, a toothed surface is produced to accept a chalk produced from compressed toner. The chalk has been developed by N. Semenoff for use on lithographic plates but I have found it useful with photo-etching. Another interesting texture is obtained by dusting the dry toner powder directly onto the Mylar with a brush. Subtle tints can be obtained this way.
The image on the Mylar can be re-worked or even completely cleaned off the plastic with a damp sponge. When the artist achieves his or her desired image, the toner drawing can be set with white gas very easily. After the Mylar is exposed to a photo-sensitized intaglio plate, all of the fine details and textures are present as those that can be created on a photo-lithographic plate.
This technique has not only given me the freedom to control and alter my images, but it has allowed me to create exquisite textures. It is a process that gives me the emotional power to create spontaneous images and playful gestures. I believe this is an extremely important discovery and its importance has not, as yet, been fully appreciated. It is deceptively simple -- and revolutionary in its potential."
Washes on intaglio plates are not common and might be considered by some as not true etching images. This technique is not to produce lithographic like tusche washes in the intaglio medium, as this would not be honest to either printing process. Etching has its' own particular charm that some artists prefer and are already setup to practice as printmakers. These developments will give these artists who might want to produce certain types of tints, reticulated washes and controlled brush work, the opportunity to use them within the intaglio medium. Because it is not difficult to control, the process could be of interest to the technically minded printmaker. The graphic arts are becoming more complicated as new materials are made available to printmakers; this should not become a barrier to creative expression. It is how the artist uses the materials available to them that will stand the test of time in the long run. Information similar to this has been published in LEONARDO, Volume 24, No.4, PP 389-394, 1991
RECENT RESEARCH INTO OTHER INTAGLIO TECHNIQUES
BY N. SEMEMOFF
USE OF ALUMINIUM PLATES
During 1992 Semenoff has become concerned about the high cost of zinc plates for students in his class. Experiments with common 16 gauge aluminium from a local supplier, has proven to be an alternative material. All intaglio techniques can be used just as well with editions of 25+ possible. The cost is considerable less with a 16 X 24 costing $6, compared to the standard 18 X 24 zinc plate at $54. Besides, both sides of the aluminium plate can be used to farther lower the cost to the student.
The aluminium may have scratches on it that have to be removed but good 4 X 8 foot sheets can be obtained and sheared to size by the supplier. Ordinary Mac-tac is used to protect the back of the plate from the mordant, but shellac or other blockout liquids could be used. Engraving or dry point is self evident and hard ground, soft ground and aquatinting is approached as with zinc or copper. While stannous chloride is considered the mordant of choice for aluminium, it is expensive and hard to come by. Semenoff developed a mordant from copper sulfate, salt and sodium bisulfate. Copper sulfate can be bought cheaply at garden centers while salt is available from water softener suppliers. Sodium bisulfate is the main ingredient of SaniFlush, available at the grocery store.
|Copper sulfate||1 Kilogram|
|NaCl (sodium chloride -- table salt)||250 grams|
|NaHSO4 (sodium bisulfate as SaniFlush)||25 grams|
|H2O (water -- depending on strength of bath)||10-20 Liter|
The powder is mixed by volume after an approximate weight is established for the chemicals. This is premixed dry in a five gallon plastic container and stored until needed. I would advise that an appropriate mask be worn while mixing the dry copper sulfate and sodium bisulfate, if they come in fine powder form. When the mixture takes on humidity, there is no risk in handling the powder mordant.
The dry chemical mixture is placed in the tray, using a volume measure equal needed to make a working bath. Water is added to bring the total volume up to the desired strength of the etching bath. I have also experimented with the use of a saturated solution of copper sulfate which was kept on hand to be added to the depleted solution to see what might be the total life of the bath. It was found that the bath could be extended considerably, but the build up of aluminium salts was a limiting factor. On first mixing the bath, it would test about . 1.0 pH; but on using the bath for only a very short time, the solution would stabilize at anywhere between 2.2 - 3.5 pH. This relatively weak acid solution makes it a very safe mordant to use in the class room. For those interested in trying the mordant, which is effective on zinc and aluminium, there is a separate paper on the subject.