Warm brown bronze: The rich brown, chocolate and warm earthy tones are created by chemically reacting the surface of the bronze to form a controlled patina. Hughes and Rowe describe a range of formulations using compounds such as cupric salts, ferric compounds and sulphur-containing chemicals, depending on the exact brown tone required. The heat, concentration and application method all influence the final colour.Verdigris green: The beautiful blue-green/green patina is created through the formation of copper compounds on the surface of the bronze. Copper salts such as copper acetate or copper sulphate, together with controlled moisture and other chemical treatments, can produce the characteristic green associated with aged bronze.Every patina is individual: The final colour is not simply a paint applied to the sculpture. It is a chemical transformation of the bronze surface, and the result depends on the alloy, preparation of the surface, chemicals used, heat, application technique and subsequent finishing.The finish continues to evolve: A professionally applied patina gives the sculpture its initial character, but bronze can continue to develop subtly over time as it responds to its environment. This is part of the beauty and individuality of a bronze sculpture.