Electroetch Articles

PRINTMAKING TODAY

VOLUME 4 -NUMBER 4
1995
Electroetch II
["Reproduced  by permission of the copyright owner, Farrand Press, London"]

Safe solutions from start to finish: etching to steel facing, Marion Behr reports on developments

When I started etching, I fell in love with the metal and felt we had a conversation during the work. That is still my feeling, and Electroetch enables me to keep that relationship while working safely, with the assurance that every step will work the way it should. We have had some wonderful surprises in the last two years as well.

My first article on Electroetch was written just after we received a grant from the Charles A. Lindbergh Fund to develop this process. That article (Printmaking Today 3, No. 1) was illustrated by a test plate produced during this work. Now, more than 50 plates comparing different etching modes in acid and Electroetch are complete and a set has recently been acquired by the Smithsonian Institute in Washington, DC, USA. Barbara Krakow of the Barbara Krakow Gallery in Boston sums up the reaction of master printers and gallery owners to these prints: 'The electroetchings are beautiful the quality of the surface is truly unlike any- thing available to traditional etching, and I applaud the innovation.'

Apart from the health hazards of acid etching, one of its most bothersome inconveniences is unpredictabil- Once an acid solution has been used, its strength is no longer known. Since it becomes weaker with each use, one must either run test plates (which further weakens the acid) or just guess. Electroetch eliminates this problem completely. We are still using the same zinc and copper sulphate solutions with which we started two years ago. The depth of lines created in a given time at a given voltage is still consistent with that shown on our original test plates. In contrast to acid, none of the Electroetch solution is used up. It is merely a carrier for the metal that moves from the etched plate to the collector plate. Within certain limits, the actual concentration of the bath does not affect the depth of etching a great deal. If the distance between the plates is kept constant, the depth of etches is controlled only by voltage applied and the time of exposure. Electroetch uses solutions that are constant in strength and allow the printer to work safely and accurately from start to finish. (Comparative pros and cons for the two processes are, for these and later points, summarized in the Table.)

Photo micrographs taken at Rutgers University of the first Electroetch lines cut in copper were compared with acid lines; the latter were smooth, and the glitter in the Electroetch lines was due to the exposure of the underlying crystal structure of the metal. This microroughened surface held ink more securely and led to the Microtint Effect which was reported in the first article. We previously found that, in copper, a tone could be obtained without rosin. The basic effect is due to the fact that crystal edges erode more rapidly than crystal surfaces, but the consequences extend much further than we expected.

I never knew... , 1995, by Marion Behr. Electroetch/photoetch on zinc. Plate 1: photoetch on Hyrocoat plate; upper middle and right hand images kept intact during etching, lower images substantially eliminated and painterly effect created by painting layers of hard ground (black). Plates 2 and 3: background, brush strokes into hard ground (blue and yellow).

Wherever there is a substantial edge or a set of etched lines close to each other, the microtint becomes more intense. When fabrics or any textured materials are placed on a soft grounded plate, run through a press and etched for about 30 - 45 min, a beautiful base is obtained. However, when this plate is cleaned and put back into the Electroetch bath for 10 - 90 min the Edge Focus Effect operates and the basic pattern darkens in a predictable scale from a light tone up to a deep black. If a complex base pattern is not desired as an important part of the final image, the texture should be provided by a uniform fabric such as silk or tarleton, but more complex patterns will give a background which can be clear or subdued depending on the times chosen for the initial soft ground etch and the second Microtint etch. As in acid etching, areas can be blocked out in traditional ways.

This extends the rosin free Microtint approach to zinc, as well as copper. All traditional soft ground approaches work extremely well, even if they are not followed by a Microtint step. A participant in one of our work shops had prepared a soft ground plate using the sides of the graphite portions of pencils of varying degrees of hardness over the paper. The image resulting after a 35 min etch was lovely to behold.

Photoetching has been avoided by many etchers because of the unhealthy solvents used with the traditional KPR (Kodak photoresist) plates. Revere Metals kindly provided us with some of their new ecologically safe zinc plates which are presensitized and can be developed in warm dilute caustic soda. The photo image is created in the sensitized layer using a positive transparency carrying a dot grid in the traditional manner. The developed image is then etched. In the print shown in this article, a part of the original photo image was left intact and the other sector was built in a painterly manner by blocking out and building tones with hard ground as a resist. The plate was worked a number of times. No rosin was used, the grid dots generated the edge focus effect to create the tones.

While Electroetch gives microrough- it 'cuts' perpendicularly to the main surface of the plate. This is because the metal ions like to travel straight to the collector plate. This means there is little undercutting and no need to feather the surface of the plate while embossing it in order to get a straight wall. The predictability of the system makes it possible to form a variety of levels for viscosity prints. In addi tion to the normal Microtint, the embossed surfaces can be further manipulated by either of the soft ground methods above. Resists may be applied alone or, after application to the plate, with physical penetrants such as stiff brushes, steel wool or the like, or with solvents which thin the resists to the point where ready break through occurs.

'Finish' means steel facing to enable many more prints to be pulled from a copper plate. This has always been thought to be a bit of 'difficult magic', best left to specialists. In fact, using Electroetch equipment, steel facing is very easy. The traditional approach uses between 6 and 12 volts. This is much too high for good plating: any irregularity in the surface will build up rapidly. This is why traditional steel facing requires frequent abrading of the plate. In steel facing using the Electroetch processor, the plate must still be scrupulously clean of grease or even finger marks; it is then attached to the cathode (-) rather than the anode (+) used in the etching step and the power contact should still be to the bottom edge of the plate. The plating step takes from 45 to 90 min. The plate should be cleaned with whiting in clear ammonia (not sudsy, because it also contains detergents) every 20 min or so. This ensures a mirror-like surface on the unetched parts of the plate. Metal polish, such as Naxon or Brasso, should not be used for intermediate cleaning since they contain a small amount of a greasy substance which imparts a sheen when rubbed with a soft cloth, but leaves a very thin layer which interferes with good plating. The sensitivity of the coating to oxidation is, of course, unchanged. When the plate is not in use, it must be thoroughly dried and coated suitably with a thin layer of hard ground.

The processor as well as the process has grown. Our most recent tank will accommodate one 610 x 915 mm (24 x 36 in) plate or several smaller ones not more than 915 mm (36 in) wide, when placed side by side in the holder. The tank is made of welded Lexan, is leak proof and is equipped with a powerful internal jet system which easily loosens the metal debris from the plate. There is also a filter system which can be operated off line or on line at will. This permits the jets to run at full power use during etching, but afterwards, when full power is not needed, they are used to remove all residues formed. With each step in processor growth, further experiments are necessary, so once again, it is time to explore.

Conditions

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Nitric Acid

Dutch Mordant

Zinc Sulfate

Copper Sulfate