As can be seen in these images, the balusters have been treated to remove the dirt, along with the original protective layer, which appears to be shellac. Made of copper plated cast iron, the fresh copper plate skin is exposed with its original dark oxide in the recesses, designed to emphasize the relief designs. The highlights are then burnished to increase the contrast with the dark background, and each piece lacquered, waxed and buffed to dramatically reduce future oxidation.