How Chemical Patination is Carried Out
World CopperSmith would like to share with you some inside knowledge about what happens before our quality copper products go on the market and after they gracefully age in your home. For those curious, we have detailed the patina process used by our professional copper artists. Each and every product we provide is truly a unique masterpiece in itself, in reading more you will learn about the detailed process that needs to be completed with proficiency.
The Patina Process
A suitable work area is selected; it should be dry, spacious and well lit. If the torch technique is to be used, the work area should be free of flammable substances. The workpiece is then securely mounted on the work bench. The object should not be in direct contact with the floor as that might lead to tide marks.
Further, the supports should not be made of steel as it will contaminate the applied patina. The object is cleaned to ensure that it is free from foreign particles or grease. Sufficient chemical solution for the patination process is prepared and thoroughly mixed. The chemical solution is then kept in a chemically inactive can to avoid possible contamination. Observe high level keenness while mixing the chemical solution or the entire process will be in jeopardy. To that effect, only distilled water is used to dilute the solutions, tap water might be a possible source of contamination.
Once the chemicals are ready, the artist should wear protective gear ready to apply the patina. In most cases, the patina is applied using the Hot Torch Technique. The artist should be very sensitive to the amount of temperature used. Very high temperatures will cause the chemical solution to boil off, leaving a trace of the patina.On the other hand very low temperatures will cause the patina to adhere poorly to the copper surface. When applying the patina, move the torch in circles over an area instead of focusing it in one place, this is because concentrating the torch in one area can lead to overheating.
At times, patina discoloring may occur. The artist is supposed to quickly apply cold and clean (distilled) water at the affected part and rub it off using a clean soft brush. Once the application process is over, the object is left to allow the patina to adhere to the surface.
What is the Purpose of the Patina?
The patina plays a very crucial role on the surface of copper. The final patina layer is mainly composed of sulfate; the sulfate patina is highly resistant to corrosion and hence protects the underlying copper body from further weathering. The more patina is formed, the more durable the sulfate layer becomes; reducing the rate of corrosion.
How Long Does it Take For Patina to Occur?
The rate of patination depends on several factors, and hence takes different lengths of time in different environments. For instance, in marine environments, the process of patination takes about seven to nine years. On the other hand, copper patination takes about fifteen to twenty five years in industrial environments. In rural areas, the entire process may take a whole thirty years to develop.
In marine environments, the surrounding environment has high humidity and a high salt concentration. Exposure of copper to salt accelerates the whole process of patination. In other words, salt acts as a catalyst in the patination process. Moisture provides a favorable environment for the reactions leading to patination to occur. This explains why the patination process takes such a short time in marine environments as compared to urban and rural areas.
Urban areas have an environment that has a high concentration of airborne sulfur dioxide, which makes the patination process take a shorter time as compared to rural areas whose environments has very low concentrations. In arid areas, patination might not form at all due to scarcity of moisture, which is an important factor in the patination process. In case it occurs, it only matures to nut brown or ebony color. Other factors that affect the rate of formation of patina are the composition of copper and the sloppiness of the surface. Pure copper forms patina at a faster rate as compared to alloyed copper under the same conditions.
Sloppy surfaces tend to form patina at a slower rate as compared to the flat surfaces under the same conditions; this applies to all environments except marine environments. This is because of runoff depriving the surface the humidity required for the patination process, however in marine environments; there is enough humidity for patination.
Soon we will be continuing this blog post, there is just so much information about Copper Patina that we would like to share with you. Our next blog will be talking about some World Monuments that are made with Copper and thus have developed an undeniable copper patina. Browse through our selection of quality copper home products or contact World CopperSmith today online or at 888-431-4677!