Some metals such as copper and bronze are prone to tarnishing. Over a long time chemicals form on the surface of the metal when it is exposed to the elements; air, water, rain, sulphur and carbon dioxide. Here are some examples of corroded metal found on the beach here in Ryde on the Isle of Wight. The textures, degradation and salt water corrosion are stunning.
Nature is truly the best at patination though, copper has been used in many applications for the beauty that happens when it is exposed to the elements. Architects use the material to clad buildings to create stunning designs that weather and improve aesthetically with age. Depending on the environment, different types of patina will form. When you are located in a salt water/marine environment like here on the Isle of Wight the patina process occurs much quicker than when inland.
Rust and patina often describe the same effect. A rust ‘patina’ refers to steel and iron which corrodes with a red russet finish. That red colour is a coating of rust oxidation. A dark ‘patina’ refers to the surface texture that forms on copper, brass and bronze, usually a dull black colour.
As a copper wire and metal artist, part of my day is working with patina to create an aesthetically pleasing affect. I use liver of sulphur solution to prematurely patina the copper to a very dark matt black finish. Once rinsed and dried I then polish away the raised surfaces to bring out the metallic highlights once more. This is my favourite treatment for copper as it gives incredible depth and texture to my designs.
I also use a treatment that creates a premature green verdigris finish. This is applied in layers and transforms the copper with a textured surface coating of greens and blue tones.
The majority of my designs are sealed with a high quality copper metal varnish. I seal the pieces for longevity, as otherwise the copper will darken with a natural dull patina over time. That said, all metal varnishes are semi-permanent which means the pieces will need re-coating in the future. When it needs re-coating all depends on where you live and the type of atmospheric elements the design will be exposed to.
Read more about why raw copper turns skin green in my article here.
Read my copper after-care guide which advises on how to look after your copper products for the best life-span.