We’ve been using copper since the first days of agriculture
Copper has been used by people for about 9,000 years and it doesn’t look like we’re going to stop anytime soon. Since copper use is common to all the trades it might be cool to learn more about it.
Copper is a “native metal”
Copper is one of the few metals that can be found in nature as a directly usable metal. The probable reason that copper was the very first metal used by our ancestors is that they found usable chunks of copper (ingots) that were ready to go. No extraction or smelting needed. Of course that only goes so far, so in about the 5th millennium BC someone discovered how to smelt it from ore.
Copper discourages bacterial, viral and fungal growth. So much so that it is currently being used in medical research, door knobs, countertops and handrails to deter illness. The ancient Egyptians sometimes used pounded copper piping to transport water from their wells. A handy side effect was that the copper acted to keep the water clean.
Our name for it comes from an island
One of the biggest copper mines in the days of the Greeks was on the island of Cyprus. The Greek word for Cyprus is Kúpros, the Romans called copper aes Cyprium (metal of Cyprus), and Shakespeare probably knew it as coper.
Copper plays well with others
Exhibiting a wide range of characteristics copper is alloyed with zinc to make brass and with tin to make bronze. Almost any metal will do, aluminum, beryllium, lead, manganese, nickel, silicon, silver.
Old Ironsides was clad in copper
In the mid-18th century ship builders began using copper to clad the hulls of wooden ships. The cladding was found to prevent the damage caused by teredo worms that bored into wooden hulls below the water line. The USS Constitution (Old Ironsides, launched, 1797) was clad with copper, also making it resistant to barnacles. Many large ships, including aircraft carriers, are coated with copper or copper paint today to make the hull resistant to barnacles. That makes them easier to clean and reduces drag in the water and helps prevent corrosion.
It is easy to change copper’s structure
The crystalline structure of copper can be manipulated to make it harder or softer. Annealing, by heating it, makes copper’s structure more organized, the result is softer and easier to bend. Planishing makes the structure less organized, therefore more rigid. Planishing can be done by pounding or rolling the copper; hence the term “hard rolled copper.”
Copper has a historical age named after it
The first metal age is called the Chalcolithic (4500 BC - 3500 BC), or Copper age. The Chalcolithic ended when someone tripped and dropped their tin into a hot vat of copper, making bronze. Bronze is much harder than copper so it makes better tools and weapons. Brass came along soon after when another klutz dropped some zinc into a vat of molten copper.
Copper has a lazy electron
Copper has the atomic number 29. It is in “Group 11” on the periodic table along with silver and gold. The outermost electron shell of this group of elements has only 1 (kind of low energy) electron in it. That lazy electron is credited with making these metals soft, corrosion resistant and also good at conducting electricity and heat.
There are two types of copper patina
Besides being slow to corrode, copper creates a layer of oxidation that creates a seal and prevents it from corroding any further. Kind of like self-painting metal. Soon after copper is exposed to heat, or to the outdoors, it creates a fine film of cupric oxide that is a dull blackish/brown. If copper is left out in the elements for an extended period of time it forms a different patina (called verdigris) that is composed of various combinations of copper with chlorine, sulfur or carbonate. Verdigris has a familiar dull green color that can be seen on old copper clad roofs.