Etching Brass the Easy Way!
Etching is the first indirect technique of engraving used as an expressive means since ancient times, as it gives the artist great creative freedom, without the long apprenticeship that characterizes other means of artistic expression. Its origin most plausibly dates back to the Middle Ages, when nitric acid (aqua fortis, as the medieval alchemists called it) was used to etch decorations into weapons and armor. Later, in the late fifteenth and early sixteenth century, the technique and name were adopted by engraving artist.
The sequence of engraving is as follows: after cleaning and smoothing the surface, the artist covers it with a thin layer of special wax, which will be darkened with lamp-black to make the wax more resistant to the acid and the engraved lines more visible. Then the artist uses a stylus to press through the wax and uncover the metal, drawing the lines that will compose the image. Once the edges and the back of the plate are protected, it is immersed in a basin containing some diluted acid.
The most commonly used types of acid are ferric chloride, nitric acid, and perchloric acid. During the "biting", that is the acid's corrosive action, the acid creates small bubbles that settle on the carved drawing. As they form, the artist removes them using the feather of an aquatic bird (which are the most resistant type), in order to obtain a regular line. Moreover, during the chemical reaction perchloric acid deposits in the furrows a rust-colored pulp, which impedes the biting; so that plates are often washed or held upside down so that the pulp falls into the basin.Using a different concentration of acid and varying the biting times different kinds of lines and results can be achieved.
Among the first to use this technique was Urs Graf, a goldsmith from Basil and the author of the first dated print (1518), and Dürer, who engraved six iron plates, including The Cannon (1518). However, it was Parmigianino who realized the possibilities of the technique and brought it to perfection.
References:
de la Croizz, Horst, Art Through the Ages, Harcourt, Brace, Jovanovich, Atlanta. p. 748
http://asuam.fa.asu.edu/printtrm.htm
Different Ways to Etch
I. Silk screen the design
II. Photo-resist etching
III. Wax
a. Equal parts beeswax and asphaltum (purchased from local craft stores)
b. Heat the metal and coat the surface with the wax.
c. Cool the metal
d. A burin is used to cut through the wax. You can use a needle stuck into a pencil eraser for finer detail. Do your cutting under a strong light bulb so the wax remains pliable.
IV. 3-M Etching Tape (expensive)
V. Spray paint/nail polish (the easy way)
Etching Medium
Use PCB etch on all types for brass etching (Radio Shack). A mixture of muriatic and nitric acid can be used to etch steel. Do not use this for brass as it will form a toxic gas.
Cleaning Your Brass
Buff your brass as it may have a coating to prevent tarnishing.
Clean the brass with some acetone before beginning the etching process.
Cutting out the Pattern
There are two ways to get your pattern onto the metal. You can lightly draw it on with a permanent marker and then paint the part you want to KEEP with a paintbrush using enamel paint (nail polish works great). Permanent marker will act as a resist, so be sure to use a slim marker and cover your lines with paint. The second way to get your pattern onto the metal is to cut the part you want to be ETCHED out of contact paper, paste it onto the brass, then spray paint the piece. After the paint dries, you can carefully peel off the contact paper to reveal the part that will be etched. Fix any problem areas with enamel paint.
Spray Painting the Metal
Use any spray paint to spray your contact paper pattern.
Don’t forget to spray all areas of the metal in either of the methods above, as the vapor from the etching medium will slowly etch any exposed metals.
PCB Etching
You can purchase PCB etch (ferric chloride) from Radio Shack. It does deteriorate over time, and the etching process will begin to take a longer time. The length of time you leave the metal in the PCB will determine the depth of the etch. You can vary the depth on a single item by painting over already-etched areas of the item and immersing it into the PCB etch for a second time.
Cleaning up the Final Product
Use acetone to remove the paint.
Buff up the brass using a buffing wheel to shine up the etched parts.