Which rivet material is prone to breakdown in moist conditions?

Copper is particularly prone to breakdown in moist conditions due to its susceptibility to corrosion and tarnishing when exposed to moisture. In environments where the humidity is high or where water is present, copper can develop a green patina known as copper carbonate, which is a result of the metal reacting with water and carbon dioxide in the atmosphere. This corrosion can weaken the integrity of the rivet over time, making it less suitable for applications where moisture is a factor.

Stainless steel, while it can corrode, is more resistant to rust and deterioration in moist environments because of its chromium content, which forms a protective layer. Aluminum is also resistant to corrosion due to the formation of a protective oxide layer, although it can be affected in very specific conditions. Plastic, on the other hand, is typically not prone to breakdown from moisture but may have other limitations such as strength or heat resistance. Thus, given the focus on moisture-related breakdown, copper is the most appropriate choice in this context.