I was recently asked to teach a two-day workshop in metalworking to a  group of art students selected from Somerset County high schools.   It sounded like a good opportunity, I said I’d do it and then I  learned that the workshop facility was pretty unsuitable for teaching  blacksmithing.  I would be working with six students in a kitchen.  A  church kitchen.  A church kitchen with new flooring that I was  specifically instructed to preserve and protect.  What to do? The scenario did prove to actually be a good opportunity for me to try a technique I had experimented with in the past, but had never  really pursued.  Using readily available materials and a safe easy technique, I spent one of the days teaching how to etch copper.  The  results were consistently good, the students were impressed and the  church kitchen remained spotless.  

Copper etching produces a design or pattern in the metal that has a  lot of ornamental potential. 

The pieces themselves are interesting,  and etching could be used, for example, around the brim of a copper  bowl or vessel.  I made a bunch of copper-etched bookmarks to give to  our favorite community workers, like our librarians, this Christmas.   My daughters made Christmas ornaments and refrigerator magnets.   Copper-etched pieces could also be worked into larger forged works. 

Any steel piece with a relatively flat surface can have thin copper  plate riveted to it as an accent.

Here’s how: 

There are a number of different techniques for etching copper, but I  think this one is particularly safe and easy. As with all etching techniques, you need an acid and a resist, which  is applied to the copper and prevents the acid from affecting the  metal.  The acid I used was Ferric Nitrate which is sold as PCB at  Radio Shack.  A 10 oz. bottle is about $5 and it can be used to etch  several pieces before becoming exhausted.   You can tell the acid is  losing its potency when it looks black and sluggish and takes longer  to get the desired etch. As a resist--and this is the incredibly easy part--you can use  Sharpie permanent markers or even better, Sharpie paint pens, which  are available in the  pen section in your favorite discount store. You can also use tape as a  resist.  I had interesting results using torn pieces of masking tape  and adhesive hole reinforcers for notebook paper. To start the process, clean your piece of copper thoroughly with a  degreasing soap.    

I wipe the metal down with denatured alcohol.   If  desired, tape the back of the piece so it doesn’t etch.  Or you can  sign the back, and your signature will etch, although usually lighter than the front. Draw your design on the front.  With clean metal and fresh acid, you  can use fairly detailed designs.  Try not to get your fingerprints on  the copper as you work. At this point, put on safety glasses and plastic gloves.  PCB is not  the worst stuff in the world, but a little caution is a good idea.   Try not to inhale it, touch it, or splash it around. Pour the PCB  into a plastic bin (deep Styrofoam meat trays work).  The etching  works best when the acid is slightly warm (temper it by placing the  bottle in warm water) and if it is agitated while the etching is  taking place.  I use an old fish tank aerator taped to the bottom of  the bin to agitate the acid.  It also works fine just tilting the  tray back and forth every ten minutes or so. Place your copper piece into the acid FACE DOWN.  I use the little  glass beads you can buy to put in the bottom of flower vases to rest  my work on.  That allows the acid to get under the piece.  It is  important to try to get rid of air bubbles once your copper is in the  acid.  Reach under your copper with a feather and rub it once or  twice or gently tap the bin and agitate it to release any bubbles  that might cling to the copper. Using tongs, check your work after about an hour.  Pieces can remain  in the acid until the desired etch is achieved.  If a piece stays  in too long, the edge of the copper will start to disintegrate. When the etch is complete, stop the acid by soaking the copper in a  bowl of ammonia for about 10 minutes.  (Watch fumes here!)  Rinse  thoroughly.  The etch can be enhanced by making the metal have more  contrast.  If you dab the copper with liver of sulfur or another  darkening agent, it will turn dark brown.  Then, take a fine grade  sandpaper or steel wool to bring out the high points. A flat clear-coat will prevent the copper from oxidizing. 

Note:  Ferric Nitrate is not available at all Radio Shacks, you need to contact a full service store.  Call ahead and make sure they have it in stock.