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Antique Brass Identification
Zinc Zn is a non ferrous base metal, which is generally found in bluish-white, yellow, brown or in black colour. Its chief and important minerals are sphalerite or zinc blende, smithsonite, calamine, zincite, willemite and franklinite. Hence zinc technology was mastered later than that of copper and iron. For pure zinc production, therefore distillation technology was developed, in which India has the distinction of being the first. Zinc is used for galvanising iron and steel, brass making, alloying, manufacture of white pigment in chemicals and medicines.
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The use of bronze dates from remote antiquity. This important metal is an alloy composed of copper and tin , in proportion which vary slightly, but may be normally considered as nine parts of copper to one of tin. Other ingredients which are occasionally found are more or less accidental. The result is a metal of a rich golden brown colour, capable of being worked by casting — a process little applicable to its component parts, but peculiarly successful with bronze, the density and hardness of the metal allowing it to take any impression of a mould, however delicate.
It is thus possible to create ornamental work of various kinds. The process of casting is known as cire perdue , and is the most primitive and most commonly employed through the centuries, having been described by the monk Theophilus , and also by Benvenuto Cellini. Briefly, it is as follows: a core, roughly representing the size and form of the object to be produced, is made of pounded brick, plaster or other similar substance and thoroughly dried.
Upon this the artist overlays his wax , which he models to the degree required in his finished work. Passing from the core through the wax and projecting beyond are metal rods. The modelling being completed, called lost-wax casting , the outer covering which will form the mould has to be applied; this is a liquid formed of clay and plaster sufficiently thin to find its way into every detail of the wax model. Further coatings of liquid are applied, so that there is, when dry, a solid outer coating and a solid inner core held together by the metal rods, with the work of art modelled in wax between.
Heat is applied and the wax melts and runs out, and the molten metal is poured in and occupies every detail which the wax had filled. When cool, the outer casing is carefully broken away, the core raked out as far as possible, the projecting rods are removed and the object modelled in wax appears in bronze.
Identifying Archaeological Metal – Canadian Conservation Institute (CCI) Notes 4/1
Determining the age of antique brass objects is a mixture of art, science and experience. Any antique brass object will have its own set of unique characteristics that will offer clues to its age. In some areas, such as statues, the art of dating old brass objects is well-developed. Singing bowls have not enjoyed this kind of academic attention.
date,Mahogany tripod has excellent optics for viewing far away objects such as. Nautical Antique Vintage Brass Pirate Spyglass Table Top Telescope.
Rachel Brazil finds out how to accurately age pottery and even metals. Dating archaeological finds still routinely relies on typology and stratigraphy — what an artefact looks like and the context in which it was found.
Brass Knot Object on Stand
If you enjoy collecting antiques or found artifacts and restoring them, you may be interested in learning to identify old brass. Brass comes in many different alloys, each with a different specific composition of metals, but is usually made of mostly copper and some zinc, although older brass alloys may also contain lead.
Check the object for encrustations resulting from the oxidation of the metal. Because brass is a cupreous metal—an alloy of copper—aged brass may resemble aged copper, with a greenish or bluish patina forming on exposed surfaces. Remove encrustations by soaking the metal object in a solution of 5 to 10 percent citric acid.
There are methods of dating sculpture based on the composition of the metal that signatures and styles can provide clues to the age of an object, but can also.
As composition of an artifact is always related to its function, this information is fundamental to archaeological research. Identification of the component materials is also the first step in proposing a conservation treatment or reventive conservation measures. Unfortunately it can be very difficult to determine the composition of archaeological artifacts.
Not only are most of them fragmentary, but burial alters their composition. The bits that remain are the materials that have best survived in the unique chemistry of a particular site. Complicating the problem is the fact that most metal objects are composites of more than one type of metal, each type contributing its unique character to the whole.
Knowledge of the characteristics of various metals, when they were produced, and how they were used will help in identifying them consult “Bibliography” for good sources of information. This Note describes a series of characteristics that can be evaluated to distinguish different metals. The most common metals found on archaeology sites are cast and wrought iron; copper and its alloys brass, bronze ; lead, tin, and their alloys pewter, Britannia metal ; and zinc either in the form of plating or alloyed with copper or lead.
Precious metals such as silver and gold may be found as plating on a base metal, or as coins and jewellery. The probability of finding a particular metal or alloy on a particular site depends on the cultural context of that site, e. Most metals can be identified to some degree using the following observations. Although it is not likely that specific alloys can be distinguished in a field situation, it is usually possible to sort artifacts according to type of alloy. Detailed elemental analysis can then be done in a laboratory.
Polish up on collecting antique and vintage brass
Bronze is an alloy of copper and tin. In the period of classical antiquity it had a low tin content, generally containing less than 10 percent, because tin was less common and therefore difficult to obtain. Like bronze, brass is an alloy, this time of copper plus zinc. It is often very difficult to distinguish between bronze and brass merely by their appearance.
Object Details. Title: Lock Plate. Date: – Medium: Brass. Dimensions: 3 7/8 x 5 1/8 in. ( x 13 cm). Classification: Metal. Credit Line: Rogers Fund.
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Bronze and brass ornamental work
Seating Seating. Tables Tables. Storage Storage. Decor Decor. Soft Furnishings Soft Furnishings. Mirrors Mirrors.
The earliest metal object of this region is a brass awl from the Sanlihe site, Jiaoxian, Shandong dating to BC. 4) The Central Plains.
The conservation and restoration of copper and copper-alloy objects is the preservation and protection of objects of historical and personal value made from copper or copper alloy. When applied to items of cultural heritage , this activity is generally undertaken by a conservator-restorer. Historically, objects made from copper or copper alloy were created for religious, artistic, technical, military, and domestic uses.
The act of conservation and restoration strives to prevent and slow the deterioration of the object as well as protecting the object for future use. The prevention and removal of surface dirt and corrosion products are the primary concerns of conservator-restorers when dealing with copper or copper-alloy objects. Copper occurs naturally as native copper and was known to some of the oldest civilizations on record. It has a history of use that is at least 10, years old, and estimates of its discovery place it at BC in the Middle East;  a copper pendant was found in northern Iraq that dates to BC.
In southeastern Anatolia, all four of these metallurgical techniques appears more or less simultaneously at the beginning of the Neolithic c. Previously the only tool made of copper had been the awl, used for punching holes in leather and gouging out peg-holes for wood joining. However, the introduction of a more robust form of copper led to the widespread use, and large-scale production of heavy metal tools, including axes, adzes , and axe-adzes.
Alloying copper with tin to make bronze was first practiced about years after the discovery of copper smelting, and about years after “natural bronze” had come into general use. Bronze artifacts from Sumerian cities and Egyptian artifacts of copper and bronze alloys date to BC.