Copper FAQs From An Expert Metallurgist
At Sinkology, we get all kinds of questions from our customers about the nature of copper. Since it is such a unique metal, many people aren’t too familiar with its finer points and distinctive properties. So, we’ve asked Walter Sperko, an expert metallurgist and copper specialist, to help answer some of the more common questions we receive about our copper sinks.
Walter J. Sperko, P.E. has a degree in Metallurgical Engineering and over 35 years of industrial experience. He is president of Sperko Engineering Services, a company that provides engineering consultation services in the areas of materials selection for different applications throughout the power, petrochemical and chemical processing industry and the fabrication and assembly of piping, boilers, and tanks to contain industrial chemical process fluids that use those materials. He is a registered Professional Engineer in several states and a Fellow of the American Society of Professional Engineers.
What materials do Sinkology copper sinks use?
Sinkology copper sinks contain 99.9% commercially pure copper. While trace amounts of oxygen and phosphorous make up the remaining 0.1%, they don’t affect the strength or corrosion resistance.
Humans have used copper for thousands of years. When people scrap copper wiring, copper plumbing tubes, tubes in air conditioners, and other sources, they recycle enough to account for 50% of the commercially pure copper produced. As long as people properly control the composition of the copper, it doesn’t matter whether the copper used to make a sink is virgin material extracted directly from copper ore, recycled copper, or a mix of the two sources.
Where does a copper sink get its strength?
Copper is as strong as automotive sheet metal. Like automotive sheet metal, forming copper makes it stiffer, stronger, and more wear-resistant. Copper sinks derive their strength from their shape and the thickness of the metal. We make our sinks from 16-gauge copper, which is 0.065 inches thick. We draw them to form smooth, rounded corners, making cleaning easy. The box-like shape of the sink adds rigidity, preventing bending and flexing during use.
Our sinks are hot-formed to achieve their general shape, but the forming temperature isn’t high enough to soften the copper. After forming, we hammer the sinks, which cold-forms and hardens the copper surface, making it damage-resistant.This process is similar to cold rolling in sinks made from cold-rolled copper. One advantage of hammering is that cold-rolled copper softens significantly when welded. This makes weld lines on welded sinks much softer compared to the seamless hammered sinks.
Will my copper sink corrode?
Copper naturally corrodes in the presence of moisture. Maintaining the luster and appearance of a polished copper sink requires regular wiping and occasional polishing. Sinks with antique finishes have already oxidized to the natural brown color of an old penny. This finish, the stable color of copper oxide, requires only regular wiping to remove mineral deposits from hard water. If an antique finish surface gets scratched, the bright copper will oxidize back to brown over time. Alternatively, you can cover the scratch overnight with a vinegar-wetted paper towel to speed up the oxidation process.
Copper flashing demonstrates 25 years of natural outdoor corrosion of copper.
Copper does not turn green in normal household environments. However, soaps can contain mild acids and salts that may create oxides in colors other than brown. The Statue of Liberty, made of pure copper like our sinks, develops a green-blue patina due to constant exposure to ocean spray containing chloride salts. This differs from the medium-brown copper oxide seen on pennies.
Normal copper oxide colors develop from deep red in the early stages of oxidation to reddish-brown as the oxide layer builds up, eventually reaching old-penny brown when fully formed. Occasional exposure to household bleach, soap, and similar cleaning agents won’t cause copper to turn green, as long as these substances aren’t left on the surface for too long. If unwanted discoloration occurs, you can usually remove it with your fingernails or a nylon scraper.
Is copper safe to use in sinks?
Most houses distribute water through copper tubes. Copper tube develops a thin oxide layer that prevents the copper tube from dissolving in potable water similar to the oxide that copper develops with normal atmospheric exposure.
Household chemicals such as vinegar, bleach, and soaps may react with copper and discolor it or change the color of the finish if left on the copper for too long. Some foods, such as grilled onions, contain free sulfur compounds that react with copper, releasing harmless mild odors into the air.
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