Red Plague -

). It occurs when silver-plated copper is exposed to moisture and oxygen, typically due to damage or gaps in the silver plating.

: It manifests as a fine, reddish-brown powder or spots on the surface of the silver plating. Red Plague

Historically, "Red Plague" has been used as a derogatory label for various political movements: Red Plague

: A galvanic cell forms where silver acts as the cathode and copper as the sacrificial anode. Red Plague