Etching.

Self-portrait frowning 1630, Rembrandt

Etched prints are generally done on metal.  The basic concept is to create the negative of an image is applied to the surface either manually with a gouge, or chemically with a masking agent and corrosive agent. 

Etching is a good way to create a print that will last a long time.  Most commonly softer metals such as copper or nickle silver is used.  

With chemical etching the artist can apply a resist in several different ways.  From photographic etching to traditional masking techniques, there are multiple avenues to take.  

Photographic etching is probably the easiest way to transfer your  desired image to the plate.  The most common way of doing a photographic etch is to develop an image and transfer it to a computer file.  The image is then printed on to a transfer paper called "P&P Blue" (press and peel blue), you must use a laser jet printer, because ink jets will not transfer properly.  Side note:  make sure you print on the NON Glossy side of the P&P Blue.  When the image is printed make sure the sheet is clean and there is no dust or hairs on the printed area,  this will hinder the resist from transferring to the plate cleanly.   To transfer the image to the plate the metal needs to be heated to between 200-225 degrees F, I use an electric griddle, I've also used a clothes iron. Clean the plate vigorously!  Over a griddle heat the metal to about 200+ degrees F, place P&P Blue printed side down over the griddle, using a wooden awl or paper towel to apply pressure to the film evenly and until the image starts to fade from the film.  

Once the image is fully transferred, you can touch up any spots that didn't transfer with a masking agent or even a sharpie.  next using packing tape cover the back of the plate and any border around the front you with not to be etched. 

Place the taped plate in the etching bath.  I have found the best method is to use a shallow dish filled with the etching solution then using packaging tape suspend the plate image side down in the bath, as though floating on the solution.  This allows the metal particle so fall to the bottom of the solution without staying on the plate (ruining the print).

Depending on the strength of the solution, the age of the solution, and even the kind of metal used all are factors in how long the plate will take to etch.  Checking every few hours is the best way to get the correct depth.  You want the etch to be deep enough that the ink will not reach down to the negative areas, yet not too deep!  If the plate is allowed to sit too long in the solution the solution will start to undercut around the edges, this weaken the borders and will make a fuzzy image. 

I have done a lot of chemical etching, this was my most used method.  However, I rarely used the plates for printing.  I most commonly used the process to create jewelry, mostly belt buckles. 

Here are a few of my etched pieces: