ForMatter/Finishes/patina/Verdigris (copper / bronze green)
finish_patina_verdigris

Verdigris (copper / bronze green)

patina · patinated · green patina, copper acetate green, Statue of Liberty green

The blue-green crust that forms on weathered copper and bronze — Statue of Liberty, old church roofs, art-cast bronze sculpture. Naturally takes decades outdoors; chemists fast-forward the sequence in days with vinegar / ammonia / salt. The patina is the protection — once it's there, the metal underneath stops corroding.

Copper-corrosion products: copper acetate Cu(CH₃COO)₂ (vinegar route, fast bright green), copper chloride CuCl₂ (salt route, blue-green), copper sulfate CuSO₄ (industrial / atmospheric, chalky pale green), or natural cuprite-malachite-brochantite mix (decades atmospheric). Forced-patina recipes: vinegar + ammonia in a fume chamber over hours; or paint with cupric-nitrate solution and sponge-dry. Stable surface once formed; sealed with wax for indoor display, left bare for architectural copper where it self-renews.

character — blue-green crystalline crust, soft to the touch, irregular blooming, ancient-reading.

Finish properties

  • levelpatinated
  • subcategoryacetate / chloride / sulfate weathering
  • applies tometal

Second life

reversibilitymoderate — patinas can be stripped (acid, mechanical polishing) and re-applied; the substrate metal is preserved through the process. The historical patina cannot be exactly reproduced after stripping.
blocks substrate recyclingno
renewabilityfield-renewable — a patina can be refreshed or applied to a stripped piece by a metalsmith with the right chemistry. Conservation-grade re-patination is a specialty (Sculpture Conservation Studio practice).

Hughes & Rowe *The Colouring, Bronzing and Patination of Metals* (Crafts Council, 1991, Watson-Guptill ed. 1995); American Institute for Conservation patina-conservation guidelines.

Citations