It is no secret that copper is currently experiencing a huge upsurge in popularity. This is mainly thanks to its beautiful colour featuring heavily in the ranges of countless homeware retailers. There is, however, far more to this lustrous metal than just its appearance.
For example, it has a greater level of thermal conductivity than any other metal (except silver); roughly 60% higher than aluminium and 3000% higher than stainless steel. This means copper is capable of heating up very quickly when compared to other metals.
Perhaps a less commonly known property of copper is it being inherently antimicrobial. A wide range of harmful microbes are unable to survive for more than a couple of hours when in contact with a surface made of copper or one of its alloys (brass and bronze). This has led to it often being used for frequently touched surfaces such as door knobs, push plates and taps.
A seemingly perfect material for cooking, it is therefore no surprise that it has been used in kitchens for millennia. But exactly when did we learn to utilise copper and its valuable assets?
It is hard to pin down an exact date when copper cookware was first introduced. Pieces discovered in regions of the middle east were dated as far back as 9000BC, suggesting cooking with copper began during the Neolithic period (≈10000-2000BC). As civilisations became increasingly capable in metallurgical techniques, metals such as copper became more widely used. It would have been around this time that copper replaced stone as the material used for making tools and cooking vessels.
The use of copper is also well documented in Ancient Egypt. Not only was it used to produce water and oil containers, but it was also used to in medical practices. The antimicrobial nature of copper was exploited long before the concept of microorganisms was fully understood. The Smith Papyrus, a medical text written between 2600 and 2200BC records the use of copper in sterilising wounds and drinking water.
Although copper is essential to many processes within the human body, it can become toxic if consumed in excess. It was this knowledge that gave rise to lining copper cookware with tin, a technique used for hundreds of years to prevent copper leaching in to food.
These tin linings would eventually wear out and during the 18th and 19th century, it was common for people to send pans away to be re-tinned. This practice is becoming increasingly rare, as are the craftsmen who perform it. Despite this, there are still manufactures producing tin-lined copper cookware who also offer a re-lining service. Perhaps the best known of these is Mauviel, a French manufacturer who have been making this type of cookware since 1830.
Tin has now largely been replaced by stainless steel as an interior cooking surface. Not only is it more cost effective, but the high grade of stainless steel used in premium cookware (typically 18/10) is highly resistant to corrosion and more durable than tin.
Another way in which the virtues of copper have been combined with those of stainless steel is in copper base cookware. A base plate made from a layer copper and aluminium is fused to a stainless steel body. This is done using a process called impact bonding using 600 tonnes of pressure.
The high conductivity of copper means the base of the pan will heat much more evenly, reducing the formation of hot spots. Modern 3 ply copper cookware effectively extends this base construction up the sides of the pan also.
As manufacturing processes advanced it became possible to combine different materials to produce copper cookware made up of three distinct layers, each possessing their own unique properties. These are as follows;
1st Layer – Copper
Very high thermal conductivity allows the entire outer surface to heat rapidly and evenly.
2nd Layer – Aluminium
Provides a lightweight core with excellent thermal retention.
3rd Layer – Stainless Steel
An inert and highly durable cooking surface.