Copper Cloth owes its luscious pink sheen to its wefts of thin copper wire, the same kind of wire used in telephone cables. The wires have been treated with polyurethane by the manufacturer to prevent corrosion and brittleness, but this coating has the added benefit of making the wire easier to loom without dulling its sheen. The copper wefts glimmer through the warps of “promix,” a synthetic created from regenerated milk casein powder and the petro-chemical acrylonitrile.