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Depletion Gilding
Depletion gilding is a method for producing a layer of nearly pure gold on an object made of gold alloy by removing the other metals from its surface. It is sometimes referred to as a "surface enrichment" process. Process Most gilding methods are additive: they deposit gold that was not there before onto the surface of an object. By contrast, depletion gilding is a subtractive process whereby material is removed to increase the purity of gold that is already present on an object's surface. In depletion gilding, other metals are etched away from the surface of an object composed of a gold alloy by the use of acids or salts, often in combination with heat. Since no gold is added, only an object made of an alloy that already contains gold can be depletion gilded. Depletion gilding relies on the fact that gold is highly resistant to oxidation or corrosion by most common chemicals, whereas many other metals are not. Depletion gilding is most often used to treat alloys of gold with copp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gold
Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactivity (chemistry), reactive chemical elements, being the second-lowest in the reactivity series. It is solid under standard temperature and pressure, standard conditions. Gold often occurs in free elemental (native state (metallurgy), native state), as gold nugget, nuggets or grains, in rock (geology), rocks, vein (geology), veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as in electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sterling Silver
Sterling silver is an alloy composed mass fraction (chemistry), by weight of 92.5% silver and 7.5% other metals, usually copper. The sterling silver silver standards, standard has a minimum millesimal fineness of 925. ''Fineness, Fine silver'', which is 99.9% pure silver, is relatively soft, so silver is usually alloyed with copper to increase its hardness and strength. Sterling silver is prone to Tarnish, tarnishing, and elements other than copper can be used in alloys to reduce tarnishing, as well as casting porosity and firescale. Such elements include germanium, zinc, platinum, silicon, and boron. Recent examples of these alloys include Argentium sterling silver, ''argentium'', ''sterlium'' and ''silvadium''. Etymology The term ''sterling silver'' originally meant "silver fit to be used in the making of sterlings", ''sterling'' being another name for the English Penny (English coin), silver penny. The etymology of ''sterling'' itself is Pound_sterling#Etymology, unclear and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alchemy
Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first attested in a number of pseudepigraphical texts written in Greco-Roman Egypt during the first few centuries AD.. Greek-speaking alchemists often referred to their craft as "the Art" (τέχνη) or "Knowledge" (ἐπιστήμη), and it was often characterised as mystic (μυστική), sacred (ἱɛρά), or divine (θɛíα). Alchemists attempted to purify, mature, and perfect certain materials. Common aims were chrysopoeia, the transmutation of " base metals" (e.g., lead) into "noble metals" (particularly gold); the creation of an elixir of immortality; and the creation of panaceas able to cure any disease. The perfection of the human body and soul was thought to result from the alchemical ''magnum opus'' ("Great Work"). The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staffordshire Hoard
The Staffordshire Hoard is the largest hoard of Anglo-Saxon gold and silver metalwork . It consists of almost 4,600 items and metal fragments, amounting to a total of of gold, of silver and some 3,500 pieces of garnet cloisonné jewellery. It is described by the historian Cat Jarman as "possibly the finest collection of early medieval artefacts ever discovered". The hoard was most likely deposited between 650 and 675 CE, and contains artefacts probably manufactured during the 6th and 7th centuries. It was discovered in 2009 in a field near the village of Hammerwich, near Lichfield, in Staffordshire, England. The location was in the Anglo-Saxon kingdom of Mercia at the time of the hoard's deposition. The hoard is of "radical" importance in Anglo-Saxon archaeology. The artefacts are nearly all martial in character and contain no objects specific to use by women. The average quality of the workmanship is extremely high and especially remarkable in vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anglo-Saxons
The Anglo-Saxons, in some contexts simply called Saxons or the English, were a Cultural identity, cultural group who spoke Old English and inhabited much of what is now England and south-eastern Scotland in the Early Middle Ages. They traced their origins to Germanic peoples, Germanic settlers who became one of the most important cultural groups in Britain by the 5th century. The Anglo-Saxon period in Britain is considered to have started by about 450 and ended in 1066, with the Norman conquest of England, Norman Conquest. Although the details of Anglo-Saxon settlement of Britain, their early settlement and History of Anglo-Saxon England, political development are not clear, by the 8th century an Anglo-Saxon cultural identity which was generally called had developed out of the interaction of these settlers with the existing Romano-British culture. By 1066, most of the people of what is now England spoke Old English, and were considered English. Viking and Norman invasions chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumbaga
''Tumbaga'' is the name given by Spanish Conquistadors for a non-specific alloy of gold and copper, and metals composed of these elements. Pieces made of tumbaga were widely found in pre-Columbian Mesoamerica in North America and South America. The term is a borrowing from the Tagalog ''tumbaga''. This came from Malay , meaning 'copper' or 'brass'. It has also been spelled ''tumbago'' in literature. Composition and properties Tumbaga is an alloy composed mostly of gold and copper. It has a significantly lower melting point than gold or copper alone . It is harder than copper, but maintains malleability after being pounded. Tumbaga can be treated with a carboxylic acid, such as oxalic acid, to dissolve copper off the surface. What remains is a shiny layer of nearly pure gold on top of a harder, more durable copper-gold alloy sheet. This process is referred to as depletion gilding. Use and function Tumbaga was widely used by the pre-Columbian cultures of Central and South Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sican Culture
The Sican (also Sicán) culture is the name that archaeologist Izumi Shimada gave to the culture that inhabited what is now the north coast of Peru between about 750 and 1375 CE. According to Shimada, ''Sican'' means "temple of the Moon". The Sican culture is also referred to as Lambayeque culture, after the name of the region in Peru. It succeeded the Moche culture. There is still controversy among archeologists and anthropologists over whether the two are separate cultures. The Sican culture is divided into three major periods based on cultural changes as evidenced in archeological artifacts., ''Sican Archaeological Project (SAP)'', 2007, Retrieved 5 October 2008. Geography and location Archaeologist Izumi Shimada, founder of the Sican Archaeological Project, named the prehistoric culture which he discovered in northwestern Peru. They succeeded the Moche and preceded the Inca Empire, the historical civilization that encountered the Spanish explorers and conquistadors. The S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electroplating
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric current. The part to be coated acts as the cathode (negative electrode) of an electrolytic cell; the electrolyte is a solution (chemistry), solution of a salt (chemistry), salt whose cation is the metal to be coated, and the anode (positive electrode) is usually either a block of that metal, or of some inert electrical conductor, conductive material. The current is provided by an external power supply. Electroplating is widely used in industry and decorative arts to improve the surface qualities of objects—such as resistance to abrasion (mechanical), abrasion and corrosion, lubrication, lubricity, reflectivity, electrical conductivity, or appearance. It is used to build up thickness on undersized or worn-out parts and to manufacture metal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fine Silver
The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of ''fine metal'' therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hardness and durability of coins and jewelry, alter colors, decrease the cost per weight, or avoid the cost of high-purity refinement. For example, copper is added to the precious metal silver to make a more durable alloy for use in coins, housewares and jewelry. Coin silver, which was used for making silver coins in the past, contains 90% silver and 10% copper, by mass. Sterling silver contains 92.5% silver and 7.5% of other metals, usually copper, by mass. Various ways of expressing fineness have been used and two remain in common use: ''millesimal fineness'' expressed in units of parts per 1,000 and '' karats'' or ''carats'' used only for gold. Karats measure the parts per 24, so that 18 karat = = 75% gold and 24 karat gold is considered 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalic Acid
Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula , also written as or or . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name is derived from early investigators who isolated oxalic acid from flowering plants of the genus '' Oxalis'', commonly known as wood-sorrels. It occurs naturally in many foods. Excessive ingestion of oxalic acid or prolonged skin contact can be dangerous. Oxalic acid is a much stronger acid than acetic acid. It is a reducing agent and its conjugate bases hydrogen oxalate () and oxalate () are chelating agents for metal cations. It is used as a cleaning agent, especially for the removal of rust, because it forms a water-soluble ferric iron complex, the ferrioxalate ion. Oxalic acid typically occurs as the dihydrate with the formula . History The preparation of salts of oxalic acid from plants had been known since at least 1745, when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gilding
Gilding is a decorative technique for applying a very thin coating of gold over solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, the metal below was traditionally silver in the West, to make silver-gilt (or ''vermeil'') objects, but gilt-bronze is commonly used in China, and also called ormolu if it is Western. Methods of gilding include hand application and gluing, typically of gold leaf, chemical gilding, and electroplating, the last also called gold plating. Parcel-gilt (partial gilt) objects are only gilded over part of their surfaces. This may mean that all of the inside, and none of the outside, of a chalice or similar vessel is gilded, or that patterns or images are made up by using a combination of gilt and ungilted areas. Gilding gives an object a gold appearance at a fraction of the cost of creating a solid gold object. In addition, a solid gold piece would often be too soft or to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrum
Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. Its color ranges from pale to bright yellow, depending on the proportions of gold and silver. It has been produced artificially and is also known as "Colored gold#Green gold, green gold".Emsley, John (2003Nature's building blocks: an A–Z guide to the elements Oxford University Press. p. 168. . Electrum was used as early as the third millennium BC in the Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidion, pyramidia atop ancient Egyptian pyramids and obelisks. It was also used in the making of ancient Beaker (archaeology) , drinking vessels. The first known metal coins made were of electrum, dating back to the end of the 7th century or the beginning of the 6th century BC. Etymology The name ''electrum'' is the Latinized form of the Greek language, Greek word ἤλεκτρον (''ḗlektron''), mentioned in the ''Odyssey'', referring to a metallic s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
