Saturday, March 15, 2008

Etching Copper and Brass

Some of my customers inquire about the process by which I put the design on some of my work. The process is a chemical etch process. Very basic once the process is understood. For copper and brass I use a ferric chloride solution. This is actually a salt some of my chemically unchallenged friends say. Anyway, the process is very similar to that using acid for other metals such as silver and steel. I know of some knife makers that use ferric chloride to etch steel knife blades. I can give a reasonably deep etch in copper and brass in a couple of hours. I've used this process for etching designs and also for champleve enamel as seen on my stick pins.
We can start out with a design. Draw or trace a design that will fit on your piece. The design should have broad enough lines to allow it to be seen clearly after etching. If you've drawn the outlines, as shown the the picture, determine which part you would like to have eroded and which part is to be raised. I've used some designs which are eroded for the finished look and some I erode around the design in the form of a background. The finished drawing is then traced onto the work. I use a transparency to transfer it to metal in many cases.
If using a transparency, the design drawing is photocopied in reverse on a transparency on a copy machine. Ink jet printers will not do. There must be an emulsion on the acetate to transfer to the work. This can then be placed on the workpiece and both placed on an iron and allowed to heat. Use a burnisher or something similar to rub the dark areas to help the transfer along. Immediately and slowly lift the transparency to see the transferred design. This will probably need some touch up with a Sharpie or red Stabilo pen. Mask of large areas with brown shipping tape. Of course, another option is to just draw directly on the workpiece as shown below.
After the image is transferred and established it is suspended upside down in a plastic container and the whole thing is vibrated or aerated to accelerate the action of the bath. After 2 hours the piece is removed and cleaned up, finished, and any additional shaping is done. The picture on the left shows paper knives (letter openers) with various designs, completed and ready for a new home. Also pictured are some brass brooch pieces ready for the fastener fabrication.

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