White Bronze
Simin Lakpour
"Sefid Ruy" Book


Definition
Bronze (brass) is an alloy of zinc and copper; this special alloy is made up of copper and tin, with high tin content and presence no difference. Copper is naturally reddish, but adding a fraction of tin, produces lighter and more yellow, which can reach the whiteness of silver. Hardness and solidity of the resulting alloy is directly proportional to the increase of its tin content.

This alloy is called “Sefid-ruy” or “Haft-jush” (a kind of “Mefraq”) in Persian.

Considering their high tin content (20%-30%), these metal objects are different from those commonly known as different from those commonly known as bronze artifacts, in which the tin content does not exceed 20 percent.

Distinctive feature of this kind of bronze is the patina, which forms on its surface, in contact with harmful factors present in the environment. The patina on these objects appears either as a black layer or in the form of green or brownish red wart-like eruptions, whereas the patina of low tin content bronzes (other bronze artifacts) displays neither this wart-like appearance nor the glossy black one.

Moreover, when lightly knocked, these vessels emit a persistent ring, which explains why explains why explains why some texts refer to this alloy as bell metal and gives a clue to its use in casting bells. Also, due to the extreme luster it allows, this alloy has been used to make mirrors, and is therefore sometimes referred to as speculum, and occasionally, due to its light color, it is called white bronze. The appellation of Chinese bronze is also used, and several texts straightforwardly call it high tin bronze.