1. Why is the sculpture hollow?
A solid form would be extremely heavy and consequently very hard to move or install. It would be impossible to cast due to the pressure on the mould and internal stresses during cooling. It would also be structurally unstable.
2. Why has this sculpture been pre-patinated?
It takes decades for bronze to patinate naturally because it has a low reactivity. The patination will also be varied, which may or may not be desirable for the artist.Pre-patination gives a uniform colour, made by various oxides and salts that are chemically stable. The wax gives a shine and protects the bronze from attack by urban pollutants.
Bronze is melted in a crucible. (Courtesy of principlearttalk.com.)