Copper
kitchen sinks are a nice addition to your kitchen, but to enjoy them for a long time you must know how to care for them properly.
Copper does not react well to chemicals, which should be avoided at all costs. This removes the natural patina of the sink and it will lose its the intrinsic properties.
Dish soap and water is all you need to get your copper sink nice and clean. Make a habit of cleaning the sink every time you use it. This will also help to eliminate water spots that can appear.
This should be done only twice a year.
You can slow down the patina process by applying a protective wax to the copper surface periodically to help maintain the luster and provide better water runoff. Look for a special copper wax in stores.
Tip: If you want your sink to shine you can always use some olive oil. Just put some on a rag or a sponge to give the sink a nice polish.