These images are created by rolling melted wax or varnishing over the face of a polished copper plate and scratching through the protective covering.  The plate is then dipped in acid, creating a groove wherever the plate has been exposed.  This part of the process may be repeated several times to achieve varying tones of the same color.  The longer the plate is in the acid bath-the deeper the groove and the darker the color on the finished piece. An artist may color line etchings with watercolors or create several plates to print different colors on the same page.