After blowing the circuit breaker and fusing a dimmer coil with a bridge rectifier at 130v DC, it was time to start small — one 9v battery at a time.
I’ve been wanting to anodize titanium and use the laser to create masks for the different colors. Translucent oxides form on titanium with heat or voltage. (I also tried lasering colors into niobium, which oxidizes similarly to titanium, but didn’t find the color band with the CO2 beam — just grey/black.) With both niobium and titanium, each volt corresponds to a thickness of oxide and refraction of a color. If you start at the highest voltage and work your way down to the lowest voltage for the colors you choose, theoretically, you can strip off the protective tape mask after each color is obtained and the thicker oxides (higher voltages) will be unaffected by lower voltage oxide layers. In essence, when anodizing with a tape mask, you are using a reductive method of printmaking like linoleum block printing, only the ink is an oxide layer.
How it works – DC voltage is applied to the surface of the titanium/niobium with a sponge clipped into an electrode. The ideal electrolyte to complete the circuit is phosphoric acid, so you wet the sponge with cola, or a solution of TSP, Cafiza, or Miracle-Gro. Two factors determine the oxide layer thickness: Voltage and time. If you vary the speed of your sponge with the electrolyte across the titanium, you’ll get a variety of colors due to incomplete oxidation at and below that voltage. It’s also possible to make a gradient by starting slowly and speeding up as you sponge across the metal.
The image above shows voltage swatches from 1v to 140v. (Most of the swatches haven’t been oxidized yet.) The little squares were cut with the laser into clear packing tape and peeled off for their specific voltage. The first yellow swatch was easy — one 9v battery. As the batteries were chained in series, the voltage was read (some were weaker) and the corresponding swatch was oxidized. 99v (12 batteries) is a beautiful green that I will definitely use again. The red at 18v is also noteworthy. When the new rectifier arrives, I’ll fill in the in-between voltages on the swatch sheet. It’s really liberating to be able to anodize without a $500+ commercial anodizer.
A little background on my motivation: I have a daily project (ringaday.com) that continually challenges my creativity and craftsmanship. NYC Resistor is the perfect environment to explore a variety of mediums, processes, and ideas. I’m partial to the laser. It puts the rapid in rapid prototyping. Join us for Craft Night one Thursday evening and come away with inspiration for your creative idea.