Low Tox / No-Tox approach to etching with copper
by John C. Murray

Ferric chloride has proven to be a far less harmful alternative etchant than traditional nitric acid. For one thing, ferric chloride is a corrosive, rather than an acid. This means it will not penetrate and burn your skin when you come in contact with it.  It will, however, turn your skin a bright yellow and will also stain your clothing-or anything else it touches-with that same cheerful color.  Remember to use eye protection when handling this chemical; it is also a good idea to have an eyewash station nearby or running water to flush the eyes. Ferric chloride works best with copper plates to give a nicely etched line. Until recently, copper plates could only be etched in a specially made vertical tank in order to allow oxidized residues to slough off and fall away from the line work when using ferric chloride by itself. 

Copper plate etching became radically better with the introduction of the Edinburgh etch, which combines anhydrous citric acid powder with ferric chloride. Edinburgh etch cut etching times by almost one half, and gives a razor-sharp and surgically clean line, all without having to use a vertical etching tank. Because the Edinburgh etch solution consumes the material oxidized from the line work on the plate with no accumulating residue, the plate can be etched horizontally in a tray oriented face up. Additionally, unlike etching zinc plates in nitric acid there are no bubbles to "feather" away because none are produced. Other than normal ambient circulating room air, no additional venting is needed because there are almost no fumes or odors when etching.

Copper plates have been shown to etch more cleanly than zinc using the Edinburgh etch and are also more durable, holding up to the considerable pressures of the intaglio press bed. For drypoint work, copper is a clear winner because it is a more uniform and ductile metal, allowing the stylus to incise and move across the plate more smoothly and freely than does zinc. While copper may be an expensive metal, I have found that using roofing copper is satisfactory for all types of intaglio work, including mezzotint. Roofing copper is softer than commercially available engravers copper, but experience has shown it to be sufficiently strong to allow editions of more than twenty drypoint or even mezzotint prints and fifty or more traditionally etched prints. Roofing copper is thinner than engravers plates, and this may limit the plate size to less than 11 x 14 inches. With these limitations in mind, the price offset for using roofing copper places this alternative material at less than the cost of zinc plates.  I buy flat, pre-cut 5 x 7 inch copper step-flashing from a local roofing supply company, and each piece (plate) costs me about $4.00. (Two years ago, that same 5x7" copper flashing plate cost about $1.00.  Tremendous increase in very little time.)   Now, go look up what the going rate for the same size plate in thicker engravers copper is from your friendly graphic supply source, and you will see why we should all be excited about using roofing copper.

Philosophical thought---
Earlier in my printmaking career, I was impressed with how many images could be printed from a plate and therefore tended to create and print up large editions. This quickly turned my studio into a storage facility, and I was straddled with the care and maintenance of an ever-expanding inventory of unsold prints, not quite what I had in mind as a printmaker. By keeping editions less than 20 prints, the work continues to be classified as “fine art” rather than mass produced posters.  Current thinking points toward the opinion that any edition that has more than 100 images is no longer to be considered "fine art".  It is beginning to look ever so much as a mass-produced image with diminished value to a serious collector.
A far better approach is to have “sold-out” editions, and besides that-it forces me to continue working at what this is all about: printmaking.