Definition
A green or bluish-green coating that forms on copper, brass, or bronze when those metals corrode through prolonged exposure to air, moisture, or certain chemicals. In aircraft, verdigris is commonly seen on copper electrical terminals, brass fittings, and bronze hardware, where it indicates corrosion that can interfere with electrical conductivity or weaken the connection.
Plain English
The greenish crust that builds up on copper or brass when it corrodes — like the green color you see on old pennies or copper roofs. On an aircraft, it's a sign that a fitting or terminal is corroding and may need cleaning or replacement.
Context Anchor
Seen during aircraft inspection or maintenance on copper wire ends, brass fittings, terminals, or other copper-containing parts.
Derivation
From the Old French 'vert-de-Grece,' meaning 'green of Greece,' a name given to the green pigment historically scraped from corroded copper. Knowing this helps because the word names a specific copper corrosion product — not just any green discoloration.
Why Pilots Care
Verdigris on electrical terminals can cause poor connections, intermittent electrical faults, or complete failure of a circuit. Spotting it during preflight or maintenance prompts cleaning or replacement before it causes an in-flight problem.
Analogy
It is similar to the green film that can appear on an old copper penny or a weathered copper roof.
Intuition Check
Verdigris is not just dirt or paint — it is corrosion. Wiping it off without addressing the cause means it will return, and the underlying metal may already be compromised.
Example Sentence 1
During the preflight inspection, the pilot noticed verdigris on the battery terminals and asked the mechanic to clean and retighten the connections before flight.
Example Sentence 2
Inspection of the copper bonding straps revealed early verdigris that required treatment to maintain electrical continuity.