Step 1. Cutting the plate.
If your etching plate is not precut, then you must cut it to size using a "draw tool". This fine-pointed tool is pulled across the surface of the plate towards you, each time digging a line deeper and deeper into the surface. The copper or zinc plate is usually 1/8" thick. When you have a line about 1/4 to 1/3 of the way through the plate, you can then "snap it" over the edge of the table, much like glass cutting.
Step 2. Bevelling the edge.
The edge of the plate must then be bevelled to 45 degrees with a file or scraper to keep the edge of the plate from cutting the paper when it is pulled through the press.
Step 3. Coating and Drawing.
Some etching plates come precoated but some do not. If not, you must coat the surface with an acid-resistant coating called ground. This prevents the acid from eating the plate when it is placed in an acid bath. The ground is typically made from beeswax and asphaltum and other things. When the plate is dry, you can begin to draw. I use a sewing needle stuck in a pencil eraser to draw with. Wherever you scratch through the ground it exposes the metal plate, enabling the acid to etch into the metal later on, creating a line. There are an infinite number of ways to create marks on the plate, as well as many different types of ground. This is just one method.
Step 4. The Acid Bath
When the drawing is complete, the plate is then immersed in an acid bath (usually nitric acid for zinc). This is where Etching gets it's name, from the acid etching the plate. This process forms the lines in the plate, which will hold the ink when the plate is inked before printing.
Step 5. Cleaning the Plate
The plate is then washed and cleaned with solvent to get the ground coating off and expose the drawing beneath.
Step 6. Inking the Plate.
The ink is then wiped onto the plate, making sure to get it into all the etched lines. Then the surface is wiped clean with a starched cheesecloth rag called a tarlatan. This leaves just the ink in the grooves and lines. This is called intaglio printing, as opposed to relief printing (like woodblock printing) in which the ink is just applied to the surface, not the grooves.
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