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Now that you know what design you want to etch, you need to clean the metal in order to prepare it for the resist. I use mineral spirits and isopropyl rubbing alcohol. It sounds mundane, and it is mundane I guess, but this step is very important and can spoil the etch if it isn’t done well. I put on vinyl gloves and clean the metal thoroughly with mineral spirits first, and then with the rubbing alcohol. After that I handle the metal only while wearing gloves. Fingerprints are oily and can cause the resist to lift.
Once the metal is cleaned, it is ready for the resist. I’ve tried a number of different resists and have found Rustoleum spray paint to be the best. Traditional resists, like those used by Rembrandt, were concoctions made of waxes and other substances like mastic and asphaltum. I will probably try making one of these old recipes sometime, but doing so will add another layer of complexity to the process, and I’m sure it will require a fair amount of experimentation. Etching isn’t really that difficult, but it is very careful work, and a resist that doesn’t work quite right is very disappointing—essentially, as much work goes into botching a piece as goes into one that turns out perfectly. The whole difference can boil down to how well the resist performs. There are some fine points to bear in mind regarding resist. Drawing my design by hand meant I needed the resist to possess some very particular qualities. For starters, I wanted a resist that was not too slick or too stiff to draw in. I wanted the resist to offer just enough drag to give me the same sense of control I have when drawing with a pencil on paper. And I needed a resist that would part very cleanly for my stylus, not one that would chip at the edges at all, or tear, or gum up on the tip of the stylus and clog the lines. What worked best for me was to spray on the Rustoleum and give it a little while to set up, and then draw in it before it was completely dry. If you apply the resist too thickly, or let it completely dry, it will be harder to cut through with the stylus. Just like with carving, the more force you have to apply, the greater the chance that your stylus will get away from you and ruin your design. Conversely, if the surface has no grab at all, you have no real control either.
The stylus I used was the soft tang end of an old file that I ground into the shape of a sharpened pencil. I knew I wanted my lines to be very thin—the brass back of this little dovetail saw gave me a canvas approximately ½” tall, and fatter lines would make it hard to render detail or to make tight turns without simply pulling away bits of resist I wanted to keep. I wrapped twine around the file to make it more comfortable to hold. While doing the actual drawing, I kept one of my preliminary sketches out in front of me. It is hard to describe, but having it there in the periphery of my vision seemed to help somehow unconsciously, sort of like when you are driving down the freeway daydreaming and yet somehow manage to stay within the lines.
After drawing my design, I plugged the ends of the brass back with bees wax, and also packed bees wax along the seam where the brass meets the steel. This prevented ferric chloride from seeping up under the brass and eating away at the metal from inside the back. I was careful not to get any of this wax on the design I just drew.
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