Bronze disease

Museums collect and care for a wide range of artifacts and specimens, preserving them for future generations to study and enjoy. Metal objects need a special environment to survive. Without proper care, they can crumble away.

When exposed to water, iron will combine with oxygen to form red rust. Corroding bronze generally turns blue or green. One common type of corrosion called bronze disease can cause an artifact to disintegrate. Not a biological illness, “bronze disease” appears when a bronze object is exposed to humid air. The moisture causes chlorides in the metal to interact with the air and create hydrochloric acid. The acid eats away at the bronze, creating small, bright green fuzzy patches on the artifact.

Axes in drawer

The only way to control bronze disease is to keep the artifact dry. Storage and display cases are temperature-controlled, and small bags of silica gel absorb moisture in the air to keep humidity down.

Museum workers also take care to never touch metal objects with their bare hands. Oil from your fingers can also cause corrosion—perhaps not immediately, it will show up sooner or later. For this reason we always wear gloves when handling metal artifacts.

Want to learn more about Bronze Age tools?

Check out these web links:

• An essay explaining the relationship between the Stone Age, Bronze Age and Iron Age
• Links to sites about the Bronze Age in Europe
• Flag Fen is a famous Bronze Age site where archaeologists have recreated a Bronze Age Village
• A description of Bronze Ages around the world
• On-line museum exhibit of the Bronze Age in England…
• and Ireland