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The Counteretch Process By Eileen M. Foti One of the questions most frequently asked by artists who are beginning to work in lithography is why their counteretching attempts fail. They find that the newly drawn areas do not roll up, they roll up in an inconsistent fashion, or they eventually begin to fade during printing. There are a number of reasons why these problems arise. Below is a detailed list of possible counteretch mixtures for stones and aluminum plates and a step-by-step guide to the process. Counteretch solution is used to remove the adsorbed gum film created by the first etch on the plate or stone’s negative areas. In order for that element to again become grease-receptive so as to accommodate new drawing, this layer must be completely removed. It is critical to do a thorough job, or else overlooked traces of that gum film will affect the establishment of the newly-drawn areas. When choosing a counteretch formula, one should always opt for the least corrosive formula, so as not to damage the grain of the stone or the plate. Make sure to follow the directions given below, and remember that each time a plate is counteretched, its grain is compromised. Consider all areas that need to be counteretched and do them at the same time, therefore minimizing the number of times that the plate will need this process. Counteretch formulas for stone are: Citric acid Used primarily for stones, this mild solution will not damage the surface grain. It should be mixed as needed and not stored for more than a day. Its effectiveness in removing gum will be increased by using warm water. 1/4 teaspoon monohydrate citric acid crystals 10 oz (300 ml) warm water Acetic acid This acid is much more corrosive than citric, and therefore is not recommended for use as a trustworthy counteretch. Instead, it is very useful for removing a "ghost image" on a stone during the graining process. If the previous image is stubborn and hard to remove while still graining at the lower numbers, one can pour this mixture onto the stone and let it sit for two minutes. Rinse thoroughly with water, and then keep graining. 1 part glacial acetic acid 10 parts water Counteretch formulas for aluminum plates are: Phosphoric/Hydrochloric This is the most dependable counteretch for aluminum. However, as with all counteretches, it must be used correctly so as not to damage the grain. 1 oz (30 ml) phosphoric acid 1 oz (30 ml) hydrochloric acid 1 gal (3490 ml) water Hydrofluoric acid This type of acid is not only highly corrosive to plates, but it is extremely dangerous to people. Its vapors will cause severe irritation to the upper respiratory tract, and serious burns will result from contact with skin. This counteretch is not recommended, but if one must use it, then gloves, eye protection and a respirator or strong local ventilation is absolutely necessary. 1 oz (30 ml) hydrofluoric acid 1 oz (30 ml) ammonium alum 1 gal (3490 ml) water Mixing and applying a counteretch solution Handle acid in a well-ventilated place, wearing gloves and eye protection. If skin comes in contact with acid, wash immediately with water. If eyes come in contact with acid, call for help and flood eyes with water for at least fifteen minutes. When mixing the solution, pour the acid into a glass measuring cup, situated safely back from the counte’s edge (use plastic if pouring hydrofluoric, as it reacts to glass). Always pour acid into water, as the reverse could cause a cloud of dangerous fumes to immediately bubble up. After mixing, wash all utensils under running water. If acid spills, then neutralize the area immediately with baking soda or magnesium carbonate as an absorbent. 1. Wash plate or stone off with running water and a CLEAN sponge. 2. Pour conteretch into the middle of the wet plate/stone and with a cotton pad, begin moving it evenly over the entire image if the whole drawing is to be treated, or massage a specific area for spot treatments. Do this for one minute. A slight odor will be apparent as metal and acid react. 3. Rinse thoroughly with water. 4. Repeat this procedure two more times. The plate will discolor slightly in the treated areas. 5. Rinse thoroughly with water, blot with clean newsprint, and fan dry immediately. 6. The plate or stone is now ready to receive new drawing. After making additions, remember that the plate must be dusted with talc (rosin, then talc for stones) and re-etched. Image must then be washed out with Lithotine (then, for plate only, deep cleaned with acetone or Ancolite to remove old lacquer, which must then be replaced with a new coat), rubbed up with asphaltum, washed off with water, and rolled up with black ink. A second etch must then be applied before proofing and printing. |
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