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The Evolving Finish of Copper in Water

Copper is used in many environments and applications because of its impressive resistance to corrosion, and resistance to permeation by liquids and gases, among other superior qualities. Having been in the copper sink, tub, and accessory industry for over a decade, we have observed copper reacting to water in several unique ways. Those who have lived and worked with copper will tell you that it is a beautiful, interesting material with a unique living finish. To love copper is to understand copper, and below we will help you do just that. Today we are highlighting some common results of placing copper in water.

First, it’s important to note that not all copper products are the same, as some alloys used in manufacturing may react differently than others. The material with which our artisan sinks and tubs are crafted in high quality, recycled, 14 gauge, made of 99% pure copper and 1% zinc added for strength.

Another important note: copper does not react with pure water alone. In fact, in the presence of unpolluted water and air, copper artifacts have been found nearly pristine after thousands of years. That being said, copper in water with more reactive contents or significant pH reading will register changes. Most commonly observed among copper sink owners is a natural, slow change in copper’s finish as the material reacts with atmospheric oxygen to form a layer of brown-black copper oxide or patina.

If you live in an area with hard water (water with high oxidization or mineral content such as calcium and magnesium) it is likely that you’ll notice more distinct dark “water spots” in addition to patina. The harder the water, the more quickly those spots can appear.

Acidic water, with a pH of less than 7, can have the opposite effect. Acids remove oxidation (patina) and will “restore” copper to its raw, shiny color. If your water supply is acidic, note that it may take longer for your sink to naturally gain any natural patina coloring, and could result in spots of shiny copper.

Salt water has an effect all its own, as its combination with copper creates a green layer of verdigris, or copper carbonate, famously seen in such famous constructions as the Statue of Liberty. Verdigris is a reaction of acetic acid and copper over a period of time. Typically, copper sink owners won’t see much verdigris occur in their sinks unless located near a body of salt water, or are frequently using saline near their sink, like contact lens solutions.

If you’re looking into buying a copper sink or tub, treasure the unique characteristics of the material’s natural, evolving finish. If you’d like to send us evidence of your own experience of copper in water, feel free to email us.