My hometown copper mine has many copper industries developed, and I know a lot about copper technology.
It is not that the golden sword is brass, in fact, most of the real bronze is itself golden, and the reason why the bronze bronze sword we see is blue-green is because the outside oxidation produces a layer of patina.
People who have studied chemistry should have heard the teacher say that bronze is not pure copper, but an alloy.
Most of the world's civilizations, the first to understand the casting of metals, often are bronze, especially bronze, the mainland in ancient times has appeared bronze, Spring and Autumn Warring States Period, people in copper added other metals, such as tin.
In fact, the color of bronze is mainly determined by the content of tin, bronze is not only one color, but there are red, gold, cyan and even off-white and other colors.
In the "Record of Examination Workers" in the pre-Qin era, it is recorded: "Gold has six qi, six points of its gold and tin are one, called the qi of zhong Ding, five points of its gold and tin is one, it is called the qi of axe and jin, four points of its gold and tin is one, it is called the qi of ge ji." ”
"Three points of gold and tin are one, which is called the qi of the great blade, five points of its gold and the tin is two, it is said that it is the qi of cutting and killing, and the gold and tin are half, and it is called the qi of the flint..."
Here, for the bronze casting, the content of tin added to it is described in detail, if the tin content in the bronze is different, the final cast bronze, the effect is also completely different.
Very early, the ancients mastered in the smelting of copper, adding tin to it, by adjusting the ratio of copper to tin to change the performance of bronze, pure copper is too soft and easy to deform, must add other mineral casting alloys, in order to make the bronze harder.
Not only tin, people in the pre-Qin era will also add lead to bronze, tin can make bronze become strong, and lead can make the pattern on the bronze more supple and delicate.
Speaking of which, ancient bronzes are said to be copper, but not pure copper, but an alloy, mainly copper, tin and lead.
The addition of different other metal components makes the color of bronze also change, especially the content of tin, a little more or less will make its color, resulting in a very large and obvious difference.
Lead in bronze, does not miscible with copper and tin, often appears granular, so the effect on color is not large.
The color of bronze mainly depends on the amount of tin content in it, it is generally believed that more than 3% of impurities are deliberate alloys, if not exceeded, it is pure copper, and pure copper products, the color is orange red or purple red.
Because the bronzes seen today are all items buried in the ground for thousands of years, because of oxidation and other reasons, the color has changed greatly, especially the surface has a layer of patina, so it is called bronze.
But those bronzes that have no patina and no rust are completely different in color, such as the famous Yue King's sword.
If the content of tin in bronzes exceeds 10%, then it will appear golden, and the ancient bells and dings are cast in such a standard configuration, and weapons such as axes and knives and forks will greatly increase the tin content.
As mentioned earlier, tin is added to increase hardness, and an increase in tin content also causes bronzes to change color.
Because of the various minerals in the bronze, in different humidity environments will occur chemical reactions, and eventually interact, resulting in many different colors, so the color of the bronze is strange, and the newly cast bronzes are mostly gold and light gold.