Bronze is a popular metal used in making sculptures. In addition to bronze, though, a number of other metals are used in the casting of sculptures, including iron, zinc, lead, gold and silver. There are plenty of reasons why someone would want to determine whether a particular piece is bronze or some other material; reasons can include writing a description of a piece for insurance purposes, providing information necessary for restoring a damaged piece, considering purchasing a piece, and others. With some knowledge of what to look for, you can determine whether a casting is bronze without relying on a professional's evaluation.
Test the sculpture with a magnet. If the magnet sticks to the sculpture, it is not bronze. Magnets will stick to cast iron but not to bronze.
Inspect the surface for signs of corrosion. If the piece has been exposed to weather without proper finishing or waxing, it may show signs of corrosion. Bronze does not corrode as easily as other metals. Traces of corrosion on bronze will be have a light greenish tint. There may also be patches of black/green areas on a bronze casting.
Examine the colour of damaged pieces. If a sculpture has any recently broken or damaged areas, this will allow you to see the colour of the unfinished material. Bronze is slightly reddish and golden. Cast iron and zinc will be dark grey.
Try to scratch it a little on the bottom. Bronze does not easily scratch. If you scruff up the bottom a little bit, you should also see the colour (refer to Step 3).
Visit sculpture exhibitions at an art gallery. This provides a context to study and compare bronze sculptures with other types of sculptures.