When working with Ferric Chloride printmakers use copper plates. Sheets of metal are shipped from the maufacturer or supply store in protective boxes. By using a metal guillotine the artist can cut the large sheets into more manageable sizes. The plates are first polished and the edges are filed down to a 45 degree angle. The metal is then placed on a hot plate ( I simply use an apartment hot plate that is used to keep food warm ) which warms the material. A lump of hard ground ( tarry substance ) is placed on the warm metal and as it melts it is rolled over the surface with a brayer. Once the ground cools the artist draws through the tar with a metal scribe to expose the metal beneath.
For years we worked with Nitric Acid solutions in the studio at Cabrillo College when we etched our zinc plates. When I moved into my own studio I wanted to work with safer material that did not create as many fumes as the Nitric. Ferric Chloride is a happy solution - it is a corrosive salt that can be used to etch on copper plates.
Once the plate has been polished, beveled, rolled up with hard ground and had the image drawn on it is placed in a plastic tray with the Ferric Chloride solution. At twenty-minute intervals the plate is removed and run under cold water to remove any particulate matter that may have collected in the etched lines and is then returned to the etching solution. The longer the plate sits in the solution, the deeper the line is etched. The deeper the line, the more ink it holds.
When the artist is happy with the etching depth the plate is removed and the hard ground is washed off with paint thinner. The plate is then ready to print.
Using oil-based inks directly from the tube or pot is easy since there are so many color choices. Alternatively, the printmaker can mix her own colors by combining inks to get a unique tone. The ink is applied in a thin layer over the entire plate - I use cut down plastic epoxy spreaders for this job. Using a white, stiff cheescloth called tarltan the ink is then rubbed into the etched lines. A final hand rubbing helps remove most of the residual ink on the plate. The beveled edges are wiped down and the plate is ready to print.