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For many, there is no substitute for the look of a sink made from one of these materials.
The surface of the material is anti-bacterial,.especially copper, meaning they are very hygenic.
They are relatively straightforward to look after.
If a quality sink is purchased, they can be very durable and last a lifetime.
Copper and bronze sinks develop a corrosion coating referred to as patina. Most users find this attractive but not all.
Made from 100% recyclable material.
The short answer is they are obviously made from different metals but what exactly is the difference? Copper is a naturally occurring element, in essence meaning it contains only copper and cannot be broken down into anything else. Brass is a mixture of copper and another element zinc. Mixes of different metals are called alloys. Bronze is a mixture of copper and the element tin.
The point in mixing metals like this is that many of the properties of the mixed metal (alloy) are generally better than the ingredient metals alone. Brass is much harder and tougher than copper or zinc and bronze is generally harder and tougher than copper or tin. Of course there is a trade off and for example brass is less resistant to corrosion and is more brittle when cast. To the eye there is the obvious colour change. The extent of the change of colour is dependant on the mix. Bronze can can look like copper, brass or even silver like steel.
Compared with other materials, a good quality sink can be costly.
Untreated, the surface will develop a corrosion layer, usually referred to as a Patina. Some people find this unattractive and desire to retain the new metal look.
Pure copper can be quite a soft material, although the crafting of it should toughen the metal considerably.
These materials are susceptible to acid attack. Lemons left overnight for example may pit the surface of the sink.
Traditionally, copper sinks were simply hammered by a craftsman out of a single piece of thick copper. This obviously has the advantage of being a one piece single construction. But this technique has a number of downsides. They take a lot of man hours to produce and the consistency of quality of the finished article is heavily dependant on the skill of the craftsman. Beating the copper makes it brittle and every so often it has to be softened or annealed by heating and being allowed to cool slowly, a lack of patience can result in parts of the sink, most noticeable where the copper is bent, becoming thin, brittle and prone to tearing. There is also a practical limit on the geometry of beating copper into a one piece item. They tend to be more rounded with less emphasis on tight angles, pleasing to some eyes but not to others.
Some sinks are still made this way, most noteably from Mexico and parts of Asia and there are some very good examples on sale. Some however are not so good and are more concerned with output than quality.
Most modern copper sinks these days are made through either a combination of beating and fabrication of the copper or just fabricated. In the former, a large sheet of copper is cut into a pattern such as the very simplified example below.
A retro style sink utilising both copper and brass in its construction.
An under-mounted copper sink with a hammered finish. The sink clearly shows the natural patina that develops.
A double farmhouse copper sink.
The metal is then hand hammered to fold all the sides together and then the seams are then joined. In a plain fabrication process the sheet metal is folded either by hand or machine. There are a number of ways of joining the copper. Occasionally you find the seams just soldered. The seam is heated, a low melting lead/tin alloy is simply melted along the seam and allowed to cool. For a kitchen sink it is unlikely this method would prove satisfactory over an extended period. Brazing is sometimes used and is a big improvement on the soldering process. A much higher temperature is used and a bronze alloy is used instead of solder. With skill, brazing can be an effective jointing method. Both methods though are effectively using the bonding metal as a glue.
In the 1940's a far superior method of jointing metals like copper was developed. With this process the copper could actually be welded together using a pure copper rod, effectively turning the article back into a single piece of copper. This is by far the best method of joining copper and is the one most often used today. Soldered seams can be noticed by silver colouring or lines at the joints. If brazed they will be a brassy colour, both turning dark grey with age. Obviously with tig welding you will just notice the whole area as just copper.
A very simplified version of cutting and folding copper, brass or bronze sheet. In reality the shape is far more complex with many more folds and cuts.
A Youtube video showing the beating of a copper sink.
A selection of finishes for copper, brass and bronze sinks are available. The first photo show a various brushed finishes, polished and brushed, just brushed and brushed witha natural patina. Then hammered with patina, polished with patina and finally a plain natural finish.
A natural coating of dark, copper oxide will form on the surface over time. There will be a transition period of a partially oxidised surface as seen in the photo. Most sink owners opt for this natural method of aging. If you wish to keep a polished look you will need to have your sink lacquered. The lacquer will wear over time and it will need to be either re-coated or you will need to periodically wax the surface of the sink.
Some consumers prefer the brass look to a sink as opposed to the copper. Brass can be an attractive alternative to copper and are usually fabricated from brass sheet as brass is less ductile than copper and not ideally suited for the hammering process. They are jointed in a similar way to copper sinks and can even be brazed using the Tig process. Occasionally, sinks are manufactured using the contrasting effects of both brass and copper.
Very few off the shelf brass sinks are available and for the most part they are made to order.
Even more exclusive is the bronze sink. Bronze is even more costly than copper due to it's high tin content. This however also affords the metal an exceptional resistance to corrosion, though like most metals, you should avoid prolonged contact with strong acids or strong alkalines such as undiluted bleach or ammonia.
As in Brass sinks you will be hard pressed to find much of a choice in an off the shelf solution as most bronze sinks are made to order such as these two well constructed, bronze sinks from Sun Valley.
If your budget or your patience does not stretch to one of these sinks, some stainless steel sink manufacturers are now offering a range of sinks where the steel has been chemically treated to offer the look of copper, brass, bronze or even gold.
A large range of styles and metallic colours are available, making these stainless steel sinks a viable alternative for some consumers.
This is a question that often turns up when discussing copper sinks. The copper would have to left untouched in a wet environment for a long time for this reaction to happen. You may occasionally come across blue spots on the underside or in the relief of ornate fronts, these deposits can be easily wiped away.