Car stereo hooked up to car battery in acid/brine bath.
Closeup of the anode.
The voltage is to high to plate metals, electroplating, on the anode. Once the dissolved metals reach saturation n the water nice black/orange/green/blue-white (color depends on the metal) slimy metal hydroxides will ppt around the anode.
Close up of the aluminum amp, the shiny/right-angled machined surfaces have dissolved away, leaving the rounded rough surfaces seen here.
After about 2-3 days in the bath, the stereo is removed and the water is boiled off leaving the now granular metal hydroxides/oxides. The resulting "pigment" is mixed with a binding agent and applied to a 2D medium. This image shows two works in progress, the piece in the foreground is 2 layers of dissolved/distilled car stereo.