Glossary of Copper and Alloy Terms
(c) Vin Callcut 2002-2017. Small extracts can be used with acknowledgements to 'Oldcopper.org' website.
Helpful comments are very welcome.
This includes many terms relevant throughout the website covering antique and collectible copper and brass. Other terms will be added as they arise.
Most terms are current but others are obsolescent or obsolete terms that occur in some of the useful literature.
Some of them have been used very loosely in the past and many of the older names for alloys have many variations in composition quoted in different sources.
Trade names and most industrial terms are generally not included except where thought to be in common use.
Brass is conventionally described as ‘% copper/ % zinc’ but also has many other industrial designations and specifications mentioned.
Sources are mainly various metallurgical dictionaries, catalogues and other references. Some other sources do not agree on a few of these terms!
(If ordering copper alloys in serious quantities for production, always ensure that a current standard is specified, not just a name. This will cover composition, form, condition and properties.)
Abbreviations for element names Aluminium - Al, Copper - Cu, Iron - Fe, Gold - Au, Lead - Pb, Manganese - Mn, Nickel - Ni, Silver - Ag, Tin - Sn.
Admiralty brass 70/30 brass with 1% tin added for extra corrosion resistance.
Adnic 70% Copper, 29% nickel, 1% tin alloy for resistance to corrosion and heat.
Ageing Loose term covering some surface treatment techniques used to make objects look old. Also a metallurgical term to describe hardening an alloy by heating to a temperature where a precipitate forms from a super-saturated solid solution.
Ale warmer Copper or brass vessel, tinned internally, shaped with a conical or bulbous foot suitable for use in a fire or grate to warm ale.
Alphenide Nickel silver, generic term, also argentan
Alpakka Nickel silver, 65% copper, 22% zinc, 13% nickel
Alpha brass Brass containing up to 36% of zinc is usually the single alpha phase with good cold working properties.
Alpha-beta brass Brass containing over 36% of zinc or with other additions usually has two phases present in the crystal structure, alpha and beta. They are used for castings, extrusions and for hot stampings.
Aluminium brass High copper brass with aluminium added for improved corrosion resistance. This is often used for condenser tubes.
Aluminium bronze Copper-aluminium alloys with up to 13% of aluminium, usually also with other additions such as iron, manganese, nickel and/or silicon. These alloys are strong, hard and have excellent resistance to marine corrosion. They are therefore commonly used for making propellers, bearings, gears, valves, and pipefittings for seawater use.
Ankh Ancient Egyptian symbol for life adopted by Greek philosophers as the sign for copper. Also called Key of Life and Crux Ansata.
Annealing Heating a metal in order to soften it after hardening by cold work or heat treatment. After annealing, quenching is not necessary but may be of advantage in helping to remove scale.
Anode copper Cast slabs of copper from the fire refining processes used as starters for electrolytic refining.
Antlerite Copper sulphide ore.
Argentan Early name for nickel silver, also alfenide.
Argyrolith Another early name for nickel silver, also alfenide.
Arko Metal 80/20 brass
Arsenical copper Copper with phosphorus and arsenic additions that give good strength and resistance to fire cracking. It is used primarily for the manufacture of boiler fireboxes.
Arsenical brass Brass with improved corrosion resistance containing arsenic, and frequently aluminium.
Azurite Copper carbonate ore.
Bell metal Copper tin alloy with much higher tin content than conventional bronze in order to make it hard and sonorous. It is too brittle to be used for many other applications. The term was also sometimes confusingly used in the nineteenth century to describe a 60/40 cast brass.
Benares Ware Benares, now called Varenisi, is the Hindu Holy City and is sited in the River Ganges in India. It is in Utah Pradesh which has a long history of copper mining. Brassware is decorated with Sanskrit inscriptions and Hindu icons.
Benin Bronze Cast copper alloy products of great artistry and craftsmanship produced in Benin, Nigeria from the 13th to 19th centuries. Composition ranged from high-copper to brasses.
Beryllium copper Heat treatable copper-beryllium alloy of high strength and hardness. Used for making springs and non-sparking tools.
Beta brass A brass with very high zinc content may be mostly of beta structure. This is brittle and used only as a brazing filler alloy.
Blue vitriol &
Blue stone Copper sulphate crystals.
Blue verditer Basic copper carbonate
Bobbiere Metal 66/34 brass
Bordeaux mixture Copper sulphate-lime mixture used as an adherent fungicide, especially for grapevines.
Bornite Copper-iron sulphide ore.
Brass Copper-zinc alloy, also used to describe a memorial plate in a church, coinage or bearing block. Originally the term also covered copper-tin alloys now called bronzes. Also used to describe a tin-zinc spelter made for the manufacture of organ pipes.
Brass lump Miners term for massive iron pyrites (fools’ gold).
Brazing Joining metals by filling clean joints with a suitable filler metal. Temperatures are higher than for soldering and a good flux is usually needed.
Bremen blue Basic copper carbonate
Bristol Metal Brass, 75.5% copper, 24.5% zinc.
Britannia metal A type of pewter having the tin hardened with antimony and copper. Sometimes marked EPBM when plated. It is used mainly in sheet form but can be cast.
Britannia Silver Silver containing 4.16% of copper compared with 7.5% in Sterling Silver.
British Plate Alternative to Sheffield plate having a core of nickel silver instead of copper. Patented 1836.
Bronze Copper-tin alloy, term also loosely used for some other copper alloys. Oldest copper alloy, still ideal for statuary. The addition of tin to copper makes it easier to cast, strengthens and hardens the metal.
Brunswick Green Copper oxychloride
Burgundy mixture Solution of copper sulphate and sodium carbonate developed in 1885 for the prevention of mildew and other diseases on grape vines.
Busbars Copper bar or section used for carrying heavy currents. Busbars are generally rigid when compared to cables.
Cap copper 95/5 brass produced as strip, originally for the manufacture of percussion caps.
Cathode copper Pure copper, the product of electrolytic refining supplied for melting for the manufacture of products.
Cartridge brass 70/30 brass with very good cold working properties, especially for deep drawing.
copper glance Cuprous Sulphide ore.
Chalcopyrite Copper sulphide ore.
Chalkos Early Greek term for brass and bronze
Chasing The use of punches on a metal surface for decoration, not removing metal as when engraving.
Chatter Machining marks made by a lathe tool that vibrates more than it should.
Chevreul salt Cupro-cupric sulphate
Chinese art metal Copper-lead-zinc tin alloy containing about 15% lead, 10%zinc and 1% tin
Chinese Bronze High tin bronze containing about 22% tin.
Chrysokalk Leaded gilding metal 90.5% copper, 8% zinc, 1.5% lead
Chrysocolla Copper silicate ore.
Chrysorin Loose term covering cold working brass with 72-66% copper and 28-34% zinc.
Ciré Perdue Lost wax casting (Precision casting), used for fine details.
Clock brass Brass containing about 35% zinc and 1% lead that can be rolled to sheet for the machining of plates and gears for clocks. The lead content improves machinability and lubricity.
Coaching bottle Large copper vessel for hot water used to keep feet warm.
Coaching horn Tapered, slender copper or brass tube with brass or silver mouthpiece. Most are recent reproductions but may be collectible since production is now minimal.
Cold working Deforming a metal at a temperature below that of recrystallisation so that the metal hardens.
Continuous casting Production method for castings where the molten metal is continuously poured into an open mould while the solidified metal is slowly withdrawn and coiled or cut to length by flying saw. May be a vertical, sidecasting or upcasting process.
Common brass 63/37 brass, standard cheap brass for cold working. It is now usually a 64/36 alloy to give improved corrosion resistance.
Copperas (blue) Copper sulphate crystals
Copper plate Good quality flat copper used to make printing plates by selective etching or engraving. The term is also applied to the immaculate type of flowing handwriting typical of that used on copper.
Copper plating Thin layer of copper electroplated on to other metals to improve appearance, corrosion resistance or provide a good bonding substrate for nickel and chromium plating.
Copper bottom To sheath the bottom of ships with copper to prevent attack by the Toredo worm and prevent the attachment of biofouling including molluscs that slow the ship, first applied to British ships in 1761. Now used as a term of assurance of quality.
Copper head A venomous snake, common in the United States of America
Copper-nickel Covers copper alloys with less than 50% of nickel.
Copper nose Slang term for inflamed nose, acne rosaaca, a bacterial infection frequently treatable by antibiotics.
Copper plate A polished plate of rolled copper on which a design is engraved for printing. Also describes plating of copper on to other metals.
Copper wall Term used in sugar making to describe a double row of copper pans served by a common fire.
Corinthian bronze Alloy produced at Corinth, much prized for ornaments, said to be of gold, silver, and copper.
Covellite Copper sulphide ore.
Cramping Jointing technique giving a ‘dovetail’ appearance, see text.
Crystalisation Metals solidify with a crystalline structure that may be subsequently be revealed at breaks or by etching a polished surface.
Cuivre Poli 70/30 brass
Cullen plate Plates for monumental brasses made in Cologne, Germany during the middles ages.
Cuprite Copper oxide ore.
Cupronickel Obsolete term for copper-nickel alloy.
Cymbal metal Brass, 78% Copper, 22% zinc that can be rolled to give a brass of good acoustic resonance.
Dairy bronze A nickel silver containing 20% nickel, 8% zinc, 4% tin and 4% lead used for some ornamental castings.
Deep drawing Forming deep, hollow components from sheet or strip by using a punch to push metal into a die.
Deoxidised copper Copper that has had deoxidiser added to reduce oxygen. Phosphorus is commonly added but other elements such as boron or magnesium may be used.
Dezincification Selective corrosion of the beta phase of duplex brass that leaves a copper residue under a ‘meringue’ of zinc oxide.
Dragons Blood A resin compound used by etchers to prevent undercutting of designs on copper plate.
Drawing The process of pulling a metal through a die to produce wire. (Not to be confused with Deep Drawing).
Ductility Ease with which material can be formed, for example by drawing, bending or rolling.
Duplex brass Brass containing over 36% of zinc or with other additions usually has two phases present in the crystal structure. They are used for castings, extrusions and for hot stampings.
Dutch brass Early term for 80/20 brass.
Dutch gold 80/20 brass rolled to foil.
Electro-plate Term applied to process for coating copper with silver. Not to be confused with Sheffield Plate.
Electum In antiquarian times, a pale yellow alloy of gold containing about 15-45% of silver but also used in the mid 19th century to cover a copper-26% nickel-23% zinc (high nickel-silver type) alloy. Electum is from the Greek word for amber.
Embossing Raising or beating out metal from the back.
Emerald copper A copper silicate ore.
Emerald green Basic copper aceto-arsenate
Engravers’ brass Good quality brass sheet containing about 63% copper. 35% zinc and 2% lead. This is a free-machining version of cartridge brass.
Engraving copper Excellent quality copper sheet with good surface finish suitable for engraving. For printing plates it may contain a little silver.
Extrusion A hot working process in which a heated billet is forced to deform by being pushed through a die to produce a long product of uniform cross-section. Squeezing toothpaste from a tube is analogous.
Fire-refined copper Copper refined by melting and processing in an open hearth or rotary furnace.
French verdigris Basic copper acetate
Galvanic corrosion When dissimilar metals are exposed to dampness, one will corrode in preference to the other. The one that does not corrode is described as ‘more noble’.
German Brass Early term for 80/20 brass
German silver Obsolete term for nickel silver.
Gilding Applying a very thin coat of gold to a metal for appearance and corrosion protection.
Gilding metal Brass with high copper, usually 90/10 but sometimes 85/15 or 80/20. These alloys have excellent cold ductility, strength and corrosion resistance. Colour varies with copper content. Used for manufacture of jewellery, springs and bellows.
Gilt metal Very loose term used to describe whitemetal or brass that may be gilded.
Guinea gold Gilding metal containing 12-15% zinc in early for cheap jewellery. Similar to Pinchbeck.
Gunmetal Hard, strong copper-tin-zinc alloy that is easily cast. The alloys now usually contain lead to improve machining characteristics and bearing properties.
copper Standard form of copper for electrical purposes with a purity giving a conductivity of 100% IACS (International Annealed Copper Standard) or more.
High tensile brass Brass with additions, typically iron, nickel, manganese and/or aluminium to give better strength and, usually, better corrosion resistance.
Hot working Forming a metal at a temperature high enough to promote recrystallisation, thereby keeping it soft by preventing cold working.
Jeweller’s bronze Brass containing 9% zinc and 2% tin with very good malleability and ductility.
Keir’s Metal Brass containing 40% zinc and 5% iron developed in 1779 and used for the manufacture of window frames.
Laiton French word for brass.
Latten Elizabethan term for brass, probably of Dutch origin.
Leaded brass Very common type of brass used for casting, extrusion or hot stamping. Lead is added to give excellent machinability.
Leaded Bronze Copper-tin casting alloy with addition of lead to improve castability and machinability.
Malachite Copper carbonate ore frequently used as a semi-precious stone for jewellery.
Manganese bronze Obsolete term for the high tensile brass that is sometimes used to make propellers.
Manganin Alloy with 84%copper, 12% manganese and 4% nickel used in wire form for making heating elements.
Manila gold Gilding metal with 12% zinc and 2% lead used for jewellery
Mannheim gold Gilding metal with 9.5-10%zinc and 0.5-1% tin used for jewellery, harder than most brasses.
Market brass Obsolete term for 65/35 brass.
Messing German word for brass.
Mirror alloys A group of copper-tin alloys with high reflectivity when polished. 60-70% copper, 10-30% tin and various additions of other elements such as antimony, arsenic, nickel and zinc.
Monel A 70/30 nickel-copper alloy, originally produced directly from a copper-nickel ore in Sudbury, Ontario. It is strong and has good resistance to corrosion.
Mosaic Gold 65/35 brass strip used for inlays
Muntz metal A 60/40 brass developed in 1832 with good castability and hot working properties.
Musiv Gold Another old term for cold working brass with 66-70% copper and 34-30% zinc.
Native copper Metallic copper found as deposits filling cracks in sandstones and conglomerates, usually as thin films but can occasionally be massive. Many globular lost wax cast reproductions are now about, ‘made from native copper’.
Naval brass 60/40 brass with 1% tin added for extra corrosion resistance.
Nickel silver Copper-nickel-zinc alloy.
Niello a black composition of sulphur with silver, lead, or copper, for filling engraved designs
Non-sparking tools Hammers, chisels and other tools made from beryllium copper or aluminium bronze for use in flammable hazard areas such as coal mines.
Nu-gold A gilding metal containing 12% zinc used for decorative purposes.
Nuremberg gold Copper alloy for jewellery containing 7.5% aluminium and 2.5% gold.
Old Copper Culture Earliest metalworking period in America using native copper found near Lake Superior as early as 4,000 years BC.
Ormolu A gilding process introduced in mid 17th century using powdered gold in a mercury amalgam applied to metal and then heated to evaporate the mercury as a very toxic vapour.
Ormulu A variety of copper-tin-zinc alloys with colours ranging from yellow to gold.
Paktong Also Packfong and Pai-t’ung. Chinese terms for copper-nickel-zinc alloys. The alloy was imported into England from about 1680 to 1820 mainly in ingot form for casting candlesticks and similar articles. Superseded in Europe by German silver (nickel silver)
Patina A protective film that develops on copper on exposure to the atmosphere. In most non-polluted environments it is basic copper carbonate but in industrial and urban areas it is mainly basic copper sulphate.
Paris Bronze Loose term for a brass containing 88% copper, 10% zinc and 2% lead used to produce trinkets and artistic souvenirs.
Paris Green Copper aceto-arsenite, used as a fungicide. It was also used as a pigment in some Victorian wallpaper, giving a significant health hazard.
Pen metal 85/13 brass with 2% tin.
Phosphor bronze A copper-tin phosphorous alloy, hard and strong. With up to 7% tin the alloy can be rolled to make excellent spring strip. Around 10% tin is used for castings.
Potin An alloy of copper, tin, lead, and zinc, used by the ancient Celts and Gauls to make coins.
Pinchbeck Gilding metal containing, variously, 6-15% zinc in early use for cheap jewellery.
Poling Part of the old fire refining process that involves reducing the oxidised charge by submerging green wood in the liquid copper.
Pre-Columbian Applied to metalwork in the Americas from around 1,000 BC. Sited in Central Andean area, Ecuador, Columbia and Northwards towards Costa Rica.
Prince Metal 83/17 Gilding metal, see also Prince Rupert’s alloy.
Prince Rupert’s alloy Gilding metal produced at Temple Mills near London, with original support from Prince Rupert of Bavaria. It was originally intended for manufacture of cannon. Records of the original composition are not available. It has also been described as 75/25 copper/arsenic or copper/bismuth alloys, both of which would be brittle and metallurgically useless.
Recycling Essential economic part of the use and re-use of copper alloys for centuries.
Red Brass Term for copper-tin-zinc alloys (gunmetals) now only used in America. Previously used to describe gilding metals with 11-20% Zn
Refining Process for removing unwanted impurities from metal.
Repousée A design raised from the base, see embossing.
Reproduction Articles made as replicas of original designs. May range from similar to seriously inferior specification.
Rich gold metal 90/10 gilding metal.
Rigidised Metal Sheet or strip that has been passed through specially cut rolls to leave a regular raised pattern. ‘Hand hammering’ may be one of the effects reproduced.
Rivet brass American term for common brass (64/36).
Rolling marks Parallel lines left on cold rolled metal by rolls that have been left with grinding marks rather than being polished for finishing work.
Rolled gold Composite metal with thin gold cladding on brass or nickel-silver, rolled to thin strip for jewellery.
Scrap Unusable metal components or offcuts, generally recyclable.
Scheele’s Green Copper hydrogen arsenate, previously used for colouring wallpaper. Poisonous, see remarks for Paris Green.
Season cracking Cracks appearing in cold worked metal some time after manufacture. Actually stress corrosion caused by a combination of mild corrosion and retained internal stresses. Can be avoided, see text.
Secondary metal Metal for production made mainly from recycled scrap.
Semi-red brass American term for brass similar to gilding metals containing 8 to 17% of zinc.
Sheffield Plate Used for the manufacture of many attractive items of tableware. Silver is bonded on to one or both sides of a copper sheet before fabrication. Decorative perforations may show the copper but good craftsmen avoid this problem at the finishing stage. The process was invented by Thomas Bolsover of Sheffield in 1743.
Shrinkage crack Common in castings that have not been well fed with liquid metal during solidification.
Silver bronze Copper-manganese-zinc alloy of whitish appearance.
Silver solder High strength copper-based soldering alloy containing silver to give good wetability and fluidity.
Sinchu Japanese term for 67/33 brass.
Slush casting Term used when the initial metal skin of a casting is allowed to solidify and the remaining liquid metal then poured back out to give a thin-walled hollow casting without the use of a core.
Soldering Using a low melting point alloy to join metals. Tin-lead alloys used to be universal with compositions ranging from the 60% tin/40% lead version used for electrical joints to a 40% tin/60% lead alloy with a long freezing range used for ‘wiped’ plumbing joints. There are now lead-free alloys available for joining water supply tubes.
Speculum Copper tin alloy of high reflectivity when polished. Tin content may be between 33 and 45%.
Spelter Original term applied to zinc and/or bismuth. Loose term applied to high zinc alloys. Also used to describe high zinc brass rods used as brazing filler metals.
Spill Term used to describe surface defects in rolled metal that originated in the cast cake or hot-worked slab. Includes rokes and laps, see section on cold working. Does not include roll marks.
Spirits of salts Hydrochloric acid.
Stainless iron A steel containing chromium with good deep-drawing properties used for the manufacture of domestic sinks. It is magnetic, unlike true stainless steel.
Stainless steel Non-rusting steel containing nickel and chromium originally invented by Brearly in Sheffield. There are now many variations of these alloys, the best of which frequently contain some copper.
Statuary bronze A series of casting alloys that can contain 75-94% copper, 3-10% tin, 1-19% zinc with some phosphorus and lead.
Sterling silver Silver with 7.5% copper.
Tissers Metal Copper with 2.5% zinc and 0.5% tin
Tombac French term covering several types of composition, generally a gilding metal containing 11-20% zinc
Tornay’s Metal A gilding metal with 82.5% copper and 17.5% zinc.
Tough pitch copper Obsolete term for copper containing oxygen at about 0.03-0.07% which gave a level surface free of shrinkage cracks to the top of a casting.
Tutanag Also tutenague or even ‘tooth and egg’. Chinese term for zinc but also used to describe paktong, the nickel silver type alloys.
Verdigris A strikingly green corrosion product that forms on copper in some circumstances, a complex basic copper acetate with a composition similar to malachite.
Virgin metal Primary metal obtained directly from ores rather than recycled scrap.
Welding Joining components involving fusion of the parent metal and usually the addition of a fillet of molten metal at the joint.
Whitemetal Can apply to any metal except gold and copper but usually restricted to metals with a relatively low melting temperature.
Wrought product Component made by hot or cold deformation of a cast product, removing the original cast structure.
Yellow brass American term for 67/33 or 65/35 brass.
Yellow Metal A brass with 60 to 62% of copper, 40 to 38% zinc used for casting and hot working.