Copper Garden Art FAQs
1) What is the oxidizing process that changes copper's color?
The process is called a patina, which is when the copper naturally oxidizes with exposure to the air to gain a green of brown flecked finish on the exterior of the piece. This happens naturally to pieces that are exposed to the elements, specifically changing humidity and the various trace chemicals that are in the air. If you're purchasing garden variety copper you should expect this to occur as the piece rests in the garden bed or lawn. It isn't instantaneous and probably will not be a smooth and even coating because of the various surfaces and orientation of the piece in relation to your water sprinkler system. The finish is considered a form of antiquing and will happen to unsealed metals, including bronze as well. It is not considered a deformation of the original piece, but a natural event because of exposure to the natural elements.
2) How can you patina a piece of copper?
Natural exposure to the elements, specifically changes in humidity, will patina any piece of copper. If you want to evenly patina a piece or art of jewelry, you can put the piece in a solution of water, salt, and acid ingredients. At this point the process can become very specific based on the color you're looking for. The patina can fade to most all colors of brown and green, including brighter and darker shades. In order to differentiate several companies have listed the exact formulas of specific ammonium, chloride, nitrate, iron, sodium, and sulfate based acids that are available from chemical stores and are sometimes found in cleaning solutions and fertilizers. Always be careful when dealing with these materials because they are very caustic. The good news is that they are always heavily distilled solutions - often times only an once or two per quart. This means you can make the solution once and then bathe the piece every day for a week or two, letting it air dry to facilitate the chemical reaction on the surface. Also some recipes require you to brush the surface of the copper with a metal brush or steel wool to expose the surface completely. This creates a solid bonding surface for the chemicals. In somewhat of an ironic twist, you can actually prolong the life of a piece through the patina process, because it will add a hardened chemical layer to the exterior of the piece that will extend its life.
3) What are some famous examples of patina copper pieces?
If you think of famous patina piece of copper the 300 foot Statue of Liberty is probably the most famous example. The Statue of Liberty was delivered copper to the United States from France and quickly developed a patina naturally in the salt water harbor in New York just after the turn of the 20th century. Congress initially considered painting the statue over to prevent the beautiful patina hue, but the Army Corps of Engineers determined it to soften the surface and protect the skin, opting to paint only the interior of the statue for protection. Additional patina pieces are frequent at fountains around old Europe. The constant flow of often unfiltered well water deposited minerals on the surface and permitted the constant humidity needed to create the extra layer bond. Although fountains are commonly made of marble and other stones, bronze and copper were used in the piping. The emphasis here is on the culture and vintage appreciation of the patina copper and bronze pieces. They are commonly associated with public places and have a peaceful capacity in the sound of flowing or trickling water. In Europe especially, the fountains also depict famous historical or religious figures and often have a throwback element to ancient Rome and Greece. Modern public artwork has stepped away from this oxidization moving to smooth marble and granite as opposed to the copper and bronze pieces that are dominant in older world plazas.