The book which contained the print was A Treatise on Etching, by Maxime Lalanne, a French artist. Lalanne's book was translated from French by Mr. Koehler. But before publishing Lalanne's book, Koehler did this experiment to be sure that he understood Lalanne's etching process.

Here, from page xxiii, is Koehler's description of how he made this experimental plate:

" A Trial Plate. This plate is given to show the effect of difference in length of biting. The lines in the eight upper rectangles were all drawn before the first immersion of the plate, those on the left with a fine point, those on the right with a somewhat coarser one. After the plate had been in the bath for three minutes, it was withdrawn, and the upper rectangle on the left stopped out. The upper rectangle on the right, however, had hardly been attacked by the acid, as the lines had been drawn with a blunter point, which had not scratched the copper, while the fine point had. It was therefore allowed to bite another three minutes before it was stopped out. The other rectangles were allowed to bite ten, twenty, and thirty minutes respectively, by which means the difference in value was produced. The figures a, b, c, perhaps show the results of partial biting still better. The three were simply lined with the same point. After the first biting they all looked like a. This was then stopped out, together with the corners of b and c. After the second biting b and c were both as b now is. The whole of b was now stopped out, and part of c, allowing only the inner lozenge to remain exposed to the acid. It is evident that the difference in color in these figures is not due to the drawing, but is entirely the result of biting."

Printmaking index

Let's use Koehler's trial plate for our first experiment with etching. Your goal will be to make a plate and print a proof that resembles the diagram. We will be using Ferric Chloride etching solution rather than the acid Koehler used, so our etch times normally will be much longer. (If you don't like rectangles, you may abandon them and invent other shapes.)

After you complete this experiment, you will have worked with the major steps in the traditional process of etching. If all goes well, you'll be able to try other etching processes more confidently and creatively. So, enjoy your experiment; take it one step at a time.... and good luck!

MATERIALS REQUIRED:

Copper plate 4"x6", etching needle with sharp point, etching needle with blunt point, file, asphaltum, 3-inch brush, stop out varnish, round watercolor brush, Ferric Chloride bath (also known as Iron Perchloride), solvent, 2B pencil. (Zinc or brass may be used instead of copper. Z-Acryl may be used instead of asphaltum)

PROCEDURE:

1. Bevel edges of the plate. Apply contact paper to the back.

2. Apply asphaltum ground, allow to dry 10 minutes at 125 degrees.

3. Draw the rectangles of the accompanying diagram onto tracing paper with 2B pencil. Also, draw the letters "a", "b", and "c", near the bottom. Substitute your name for the letters "PL. A." Near the left column of rectangles, print the word "sharp". Near the right column, print the word "blunt".

4. Place the graphite tracing face down on dry asphaltum (secure with tape).

5. Rub heavily with fingers (or use burnisher or run it through the press).

6. Remove tracing paper; observe that the transferred design is reversed on the plate.

7. Use the sharp needle to draw the lines in the "sharp" column, removing asphaltum and exposing the bare copper. Do not gouge into the copper.

8.Use the sharp needle to make a pattern of regular vertical lines in blocks "a", "b", and "c" (at bottom of the diagram).

9. Use the sharp needle in the 4 blocks in the "sharp" column to make vertical lines similar to those you see on the diagram.

10. In the same 4 blocks in the "sharp" column make some horizontal lines. Draw right through the verticals.

11. Then add some diagonal lines.

12. Use the blunt needle to make similar lines in the 4 blocks of the "blunt" column. The needle will feel different as you draw with it, and the lines will be less sharp.

13. Etch the plate in Ferric chloride. Instead of 3 minutes shown on Koehler's diagram, the bite will probably need to be longer. To determine this, lift the plate from the etching tank after about 3 minutes. Rinse plate in water to remove the etching solution, and check the depth using a sharp needle as a gauge. If you can feel the depth of a bitten line, use 3 as a base line. (Remember: Koehler was using an acid that bit faster.) Most likely, you will not be able to detect the depth until the plate has bitten a few minutes longer. Keep etching until you can feel the depth with the needle. Rinse and dry. It must be dried thoroughly -- no lingering drops of water are allowed.

14. When the lines reach a depth of being just barely, but cleanly, bitten in, stop out the first block (corresponding to Koehler's 3 minute block) and use the needle to scribe the number of minutes the plate etched. Also use stop out varnish to stop out the entire "a" block at bottom. Stop out the corners of the "b" and "c" blocks, revealing a "diamond" shape in each.

15. Return to the acid. Etch for the same number of minutes again so that the remaining blocks will be bitten twice as long as the first block. Rinse and dry (thoroughly).

16. Stop out the second block (Koehler's 6 minute block) and use the needle to scribe the cumulative number of minutes the plate etched -- remember: it etched twice as long as the first block.

17. Return to the acid and double the amount of etch time again. Rinse and dry. Scribe the cumulative number of minutes. Koehler's plate shows "10", but yours will be longer.

18. Stop out both of Koehler's "10" blocks.

19. Stop out the diamond remaining in block "b" at the bottom. Also stop out larger triangles in the corners on block "c" to create a smaller diamond.

20. Return to the acid, etch the same number of minutes as the preceding etch, doubling the cumulative etch time. Rinse, dry, and scribe the number of minutes (where Koehler's plate has "20").

21. Stop out both of Koehler's "20" minute blocks. The only areas remaining exposed are Koehler's "30" minute blocks and the small triangle in the center of block "c".

22. Return to the etching tank and bite the plate the same number of cumulative minutes as before. Scribe the new cumulative total in the location corresponding to Koehler's "30".

23. Remove varnish with alcohol. Use kerosene to remove asphaltum.

24. After doing this experiment, you can forget about using your watch to determine the biting time. The clock is often an inaccurate method. Instead, you should rely on the next step (25th step) of the experiment.

25. Print the plate. Save both proof and plate for reference. When you need a certain kind of line, find a similar one on the proof, then gauge the depth of that line on the plate -- use an etching needle as your gauge. With it, you can feel the depth of the line before removing the etching ground from the plate.