Brass

Brass

Overview
Brass is an alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

 of copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 and zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.

In comparison, bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...

 is principally an alloy of copper and tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

. Bronze does not necessarily contain tin, and a variety of alloys of copper, including alloys with arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, and silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

, are commonly termed "bronze". The term is applied to a variety of brasses and the distinction is largely historical.

Brass is a substitutional alloy.
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Encyclopedia
Brass is an alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

 of copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 and zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.

In comparison, bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...

 is principally an alloy of copper and tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

. Bronze does not necessarily contain tin, and a variety of alloys of copper, including alloys with arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, and silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

, are commonly termed "bronze". The term is applied to a variety of brasses and the distinction is largely historical.

Brass is a substitutional alloy. It is used for decoration for its bright gold-like appearance; for applications where low friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...

 is required such as locks, gears, bearings, doorknobs, ammunition, and valves; for plumbing and electrical applications; and extensively in musical instruments
Brass instrument
A brass instrument is a musical instrument whose sound is produced by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips...

 such as horns and bells for its acoustic properties. It is also used in zipper
Zipper
A zipper is a commonly used device for temporarily joining two edges of fabric...

s. Because it is softer than most other metals in general use, brass is often used in situations where it is important that sparks not be struck, as in fittings and tools around explosive gases.

Brass has a muted yellow color which is somewhat similar to gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

. It is relatively resistant to tarnish
Tarnish
Tarnish is a thin layer of corrosion that forms over copper, brass, silver, aluminum, and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish; it...

ing, and is often used as decoration and for coins. In antiquity, polished brass was often used as a mirror.

Properties



The malleability
Ductility
In materials science, ductility is a solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire. Malleability, a similar property, is a material's ability to deform under compressive stress; this is often characterized...

 and acoustic
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...

 properties of brass have made it the metal of choice for brass musical instrument
Musical instrument
A musical instrument is a device created or adapted for the purpose of making musical sounds. In principle, any object that produces sound can serve as a musical instrument—it is through purpose that the object becomes a musical instrument. The history of musical instruments dates back to the...

s such as the trombone
Trombone
The trombone is a musical instrument in the brass family. Like all brass instruments, sound is produced when the player’s vibrating lips cause the air column inside the instrument to vibrate...

, tuba
Tuba
The tuba is the largest and lowest-pitched brass instrument. Sound is produced by vibrating or "buzzing" the lips into a large cupped mouthpiece. It is one of the most recent additions to the modern symphony orchestra, first appearing in the mid-19th century, when it largely replaced the...

, trumpet
Trumpet
The trumpet is the musical instrument with the highest register in the brass family. Trumpets are among the oldest musical instruments, dating back to at least 1500 BCE. They are played by blowing air through closed lips, producing a "buzzing" sound which starts a standing wave vibration in the air...

, cornet
Cornet
The cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact shape, and mellower tone quality. The most common cornet is a transposing instrument in B. It is not related to the renaissance and early baroque cornett or cornetto.-History:The cornet was...

, euphonium
Euphonium
The euphonium is a conical-bore, tenor-voiced brass instrument. It derives its name from the Greek word euphonos, meaning "well-sounding" or "sweet-voiced"...

, tenor horn, and the French horn. Even though the saxophone
Saxophone
The saxophone is a conical-bore transposing musical instrument that is a member of the woodwind family. Saxophones are usually made of brass and played with a single-reed mouthpiece similar to that of the clarinet. The saxophone was invented by the Belgian instrument maker Adolphe Sax in 1846...

 is classified as a woodwind instrument
Woodwind instrument
A woodwind instrument is a musical instrument which produces sound when the player blows air against a sharp edge or through a reed, causing the air within its resonator to vibrate...

 and the harmonica
Harmonica
The harmonica, also called harp, French harp, blues harp, and mouth organ, is a free reed wind instrument used primarily in blues and American folk music, jazz, country, and rock and roll. It is played by blowing air into it or drawing air out by placing lips over individual holes or multiple holes...

 is a free reed aerophone
Free reed aerophone
A free reed aerophone is a musical instrument where sound is produced as air flows past a vibrating reed in a frame. Air pressure is typically generated by breath or with a bellows.- Operation :...

, both are also often made from brass. In organ pipes
Reed pipe
A reed pipe is an organ pipe that is sounded by a vibrating brass strip known as a reed. Air under pressure is directed towards the reed, which vibrates at a specific pitch. This is in contrast to flue pipes, which contain no moving parts and produce sound solely through the vibration of air...

 of the reed family, brass strips (called tongues) are used as the reeds, which beat against the shallot (or beat "through" the shallot in the case of a "free" reed).

Brass has higher malleability than bronze or zinc. The relatively low melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...

 of brass (900 to 940°C, depending on composition) and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses. The density of brass is approximately .303 lb/cubic inch, 8400 to 8730 kilograms per cubic metre (equivalent to 8.4 to 8.73 grams per cubic centimetre).

Today almost 90% of all brass alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet. Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the desired form and size.

Aluminium makes brass stronger and more corrosion resistant. Aluminium also causes a highly beneficial hard layer of aluminium oxide
Aluminium oxide
Aluminium oxide is an amphoteric oxide with the chemical formula 23. It is commonly referred to as alumina, or corundum in its crystalline form, as well as many other names, reflecting its widespread occurrence in nature and industry...

 (Al2O3) to be formed on the surface that is thin, transparent and self healing. Tin has a similar effect and finds its use especially in sea water
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 applications (naval brasses). Combinations of iron, aluminium, silicon and manganese make brass wear and tear
Wear and tear
Wear and tear is damage that naturally and inevitably occurs as a result of normal wear or aging. It is used in a legal context for such areas as warranty contracts from manufacturers, which usually stipulate that damage due to wear and tear will not be covered.Wear and tear is a form of...

 resistant.

Lead content


To enhance the machinability of brass, lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 is often added in concentrations of around 2%. Since lead has a lower melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...

 than the other constituents of the brass, it tends to migrate towards the grain boundaries in the form of globules as it cools from casting. The pattern the globules form on the surface of the brass increases the available lead surface area which in turn affects the degree of leaching. In addition, cutting operations can smear the lead globules over the surface. These effects can lead to significant lead leaching from brasses of comparatively low lead content.

Silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 is an alternative to lead; however, when silicon is used in a brass alloy, the scrap must never be mixed with leaded brass scrap because of contamination and safety problems.

In October 1999 the California State Attorney General sued 13 key manufacturers and distributors over lead content. In laboratory tests, state researchers found the average brass key, new or old, exceeded the California Proposition 65
California Proposition 65 (1986)
Proposition 65 is a California law passed by direct voter initiative in 1986 by a 63%-37% margin...

 limits by an average factor of 19, assuming handling twice a day. In April 2001 manufacturers agreed to reduce lead content to 1.5%, or face a requirement to warn consumers about lead content. Keys plated with other metals are not affected by the settlement, and may continue to use brass alloys with higher percentage of lead content.

Also in California, lead-free materials must be used for "each component that comes into contact with the wetted surface of pipes and pipe fittings
Piping and plumbing fittings
Fittings are used in pipe and plumbing systems to connect straight pipe or tubing sections, to adapt to different sizes or shapes, and for other purposes, such as regulating or measuring fluid flow...

, plumbing fittings and fixtures." On January 1, 2010, the maximum amount of lead in "lead-free brass" in California was reduced from 4% to 0.25% lead. The common practice of using pipes for electrical grounding is discouraged, as it accelerates lead corrosion.

Corrosion-resistant brass for harsh environments


The so called dezincification resistant (DZR or DR) brasses are used where there is a large corrosion risk and where normal brasses do not meet the standards. Applications with high water temperatures, chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

s present or deviating water qualities (soft water) play a role. DZR-brass is excellent in water boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

 systems. This brass alloy must be produced with great care, with special attention placed on a balanced composition and proper production temperatures and parameters to avoid long-term failures.

Germicidal/antimicrobial applications


Main article: Antimicrobial copper-alloy touch surfaces.

See also: Antimicrobial properties of copper
Antimicrobial properties of copper
Copper and its alloys are natural antimicrobial materials. Ancient civilizations exploited the antimicrobial properties of copper long before the concept of microbes became understood in the nineteenth century...

, Copper alloys in aquaculture
Copper alloys in aquaculture
Recently, copper alloys have become important netting materials in aquaculture . Various other materials including nylon, polyester, polypropylene, polyethylene, plastic-coated welded wire, rubber, patented twine products , and galvanized steel are also used for netting in aquaculture fish...



The copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 in brass makes brass germicidal
Antiseptic
Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...

. Depending upon the type and concentration of pathogens and the medium they are in, brass kills these microorganisms within a few minutes to eight hours of contact.

The bactericidal properties of brass have been observed for centuries and were confirmed in the laboratory in 1983. Subsequent experiments by research groups around the world reconfirmed the antimicrobial efficacy of brass, as well as copper and other copper alloys. Extensive structural membrane damage to bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 was noted after being exposed to copper.

In 2007, U.S. Department of Defense’s Telemedicine and Advanced Technologies Research Center (TATRC) began to study the antimicrobial properties of copper alloys, including four brasses (C87610, C69300, C26000, C46400) in a multi-site clinical hospital trial conducted at the Memorial Sloan-Kettering Cancer Center
Memorial Sloan-Kettering Cancer Center
Memorial Sloan–Kettering Cancer Center is a cancer treatment and research institution founded in 1884 as the New York Cancer Hospital...

 (New York City), the Medical University of South Carolina
Medical University of South Carolina
The Medical University of South Carolina opened in Charleston, South Carolina in 1824 as a small private college for the training of physicians. It is one of the oldest continually operating school of medicine in the United States and the oldest in the Deep South...

, and the Ralph H. Johnson VA Medical Center (South Carolina). Commonly-touched items, such as bed rails, over-the-bed tray tables, chair arms, nurse's call buttons, IV poles, etc. were retrofitted with antimicrobial copper alloys in certain patient rooms (i.e., the “coppered” rooms) in the Intensive Care Unit
Intensive Care Unit
thumb|220px|ICU roomAn intensive-care unit , critical-care unit , intensive-therapy unit/intensive-treatment unit is a specialized department in a hospital that provides intensive-care medicine...

 (ICU). Early results disclosed in 2011 indicate that the coppered rooms demonstrated a 97% reduction in surface pathogens versus the non-coppered rooms. This reduction is the same level achieved by “terminal” cleaning regimens conducted after patients vacate their rooms. Furthermore, of critical importance to health care professionals, the preliminary results indicated that patients in the coppered ICU rooms had a 40.4% lower risk of contracting a hospital acquired infection versus patients in non-coppered ICU rooms. The U.S. Department of Defense investigation contract, which is ongoing, will also evaluate the effectiveness of copper alloy touch surfaces to prevent the transfer of microbes to patients and the transfer of microbes from patients to touch surfaces, as well as the potential efficacy of copper-alloy based components to improve indoor air quality
Indoor air quality
Indoor air quality is a term referring to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants....

.

In the U.S., the Environmental Protection Agency regulates the registration of antimicrobial products. After extensive antimicrobial testing according to the Agency’s stringent test protocols, 355 copper alloys
Copper alloys
Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead...

, including many brasses, were found to kill more than 99.9% of methicillin
Methicillin
Meticillin or methicillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It should not be confused with the antibiotic metacycline.-History:Methicillin was developed by Beecham in 1959...

-resistant Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

(MRSA), E. coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

O157:H7, Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...

, Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

, Enterobacter aerogenes
Enterobacter aerogenes
Enterobacter aerogenes is a Gram-negative, oxidase negative, catalase positive, citrate positive, indole negative, rod-shaped bacterium....

, and vancomycin-resistant Enterococci (VRE) within two hours of contact. Normal tarnishing was found to not impair antimicrobial effectiveness.

Antimicrobial tests have also revealed significant reductions of MRSA as well as two strains of epidemic MRSA (EMRSA-1 and EMRSA-16) on brass (C24000 with 80% Cu) at room temperature (22 degrees Celsius) within three hours. Complete kills of the pathogens were observed within 4 ½ hours. These tests were performed under wet exposure conditions. The kill timeframes, while impressive, are nevertheless longer than for pure copper, where kill timeframes ranged between 45 to 90 minutes.

A novel assay
Assay
An assay is a procedure in molecular biology for testing or measuring the activity of a drug or biochemical in an organism or organic sample. A quantitative assay may also measure the amount of a substance in a sample. Bioassays and immunoassays are among the many varieties of specialized...

 that mimics dry bacterial exposure to touch surfaces was developed because this test method is thought to more closely replicate real world touch surface exposure conditions. In these conditions, copper alloy surfaces were found to kill several million Colony Forming Units of Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

within minutes. This observation, and the fact that kill timeframes shorten as the percentage of copper in an alloy increases, is proof that copper is the ingredient in brass and other copper alloys that kills the microbes.

The mechanisms of antimicrobial action by copper and its alloys, including brass, is a subject of intense and ongoing investigation. It is believed that the mechanisms are multifaceted and include the following: 1) Potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

 or glutamate leakage through the outer membrane of bacteria; 2) Osmotic balance disturbances; 3) Binding to proteins that do not require or utilize copper; 4) Oxidative stress
Oxidative stress
Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage...

 by hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 generation.

Research is being conducted at this time to determine whether brass, copper, and other copper alloys can help to reduce cross contamination in public facilities and reduce the incidence of nosocomial infections (hospital acquired infections) in healthcare facilities.

Also, due to its antimicrobial/algaecidal properties that prevent biofouling
Biofouling
Biofouling or biological fouling is the undesirable accumulation of microorganisms, plants, algae, or animals on wetted structures.-Impact:...

, in conjunction with its strong structural and corrosion-resistant benefits for marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 environments, brass alloy netting cages are currently being deployed in commercial-scale aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

 operations in Asia, South America, and the USA.

Season cracking


Brass is susceptible to stress corrosion cracking
Stress corrosion cracking
Stress corrosion cracking is the unexpected sudden failure of normally ductile metals subjected to a tensile stress in a corrosive environment, especially at elevated temperature in the case of metals. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when...

, especially from ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 or substances containing or releasing ammonia. The problem is sometimes known as season cracking
Season cracking
Season cracking is a form of stress-corrosion cracking of brass cartridge cases originally reported from British forces in India. During the monsoon season, military activity was temporarily reduced, and ammunition was stored in stables until the dry weather returned. Many brass cartridges were...

 after it was first discovered in brass cartridge cases used for rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...

 ammunition
Ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...

 during the 1920s in the Indian Army
Indian Army
The Indian Army is the land based branch and the largest component of the Indian Armed Forces. With about 1,100,000 soldiers in active service and about 1,150,000 reserve troops, the Indian Army is the world's largest standing volunteer army...

. The problem was caused by high residual stress
Residual stress
Residual stresses are stresses that remain after the original cause of the stresses has been removed. They remain along a cross section of the component, even without the external cause. Residual stresses occur for a variety of reasons, including inelastic deformations and heat treatment...

es from cold forming of the cases during manufacture, together with chemical attack from traces of ammonia in the atmosphere. The cartridges were stored in stables and the ammonia concentration rose during the hot summer months, so initiating brittle cracks. The problem was resolved by annealing
Annealing (metallurgy)
Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the recrystallization temperature, maintaining a suitable temperature, and...

 the cases, and storing the cartridges elsewhere.

Brass types

  • Admiralty brass contains 30% zinc, and 1% tin which inhibits dezincification in many environments.
  • Aich's alloy typically contains 60.66% copper, 36.58% zinc, 1.02% tin, and 1.74% iron. Designed for use in marine service owing to its corrosion resistance, hardness and toughness. A characteristic application is to the protection of ships' bottoms, but more modern methods of cathodic protection have rendered its use less common. Its appearance resembles that of gold.
  • Alpha brasses with less than 35% zinc, are malleable, can be worked cold, and are used in pressing, forging, or similar applications. They contain only one phase, with face-centered cubic crystal structure
    Crystal structure
    In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...

    .
  • Prince's metal or Prince Rupert's metal is a type of alpha brass containing 75% copper and 25% zinc. Due to its beautiful yellow color, it is used as an imitation of gold. The alloy was named after Prince Rupert of the Rhine
    Prince Rupert of the Rhine
    Rupert, Count Palatine of the Rhine, Duke of Bavaria, 1st Duke of Cumberland, 1st Earl of Holderness , commonly called Prince Rupert of the Rhine, KG, FRS was a noted soldier, admiral, scientist, sportsman, colonial governor and amateur artist during the 17th century...

    .
  • Alpha-beta brass (Muntz metal
    Muntz metal
    Muntz metal is a form of alpha-beta brass with about 60% copper, 40% zinc and a trace of iron. It is named after George Fredrick Muntz, a metal-roller of Birmingham, England who commercialised the alloy following his patent of 1832....

    ), also called duplex brass, is 35–45% zinc and is suited for hot working. It contains both α and β' phase; the β'-phase is body-centered cubic and is harder and stronger than α. Alpha-beta brasses are usually worked hot.
  • Aluminium brass contains aluminium
    Aluminium
    Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

    , which improves its corrosion resistance. It is used for seawater service and also in Euro coins
    Euro coins
    There are eight euro coin denominations, ranging from one cent to two euros . The coins first came into use in 2002. They have a common reverse, portraying a map of Europe, but each country in the eurozone has its own design on the obverse, which means that each coin has a variety of different...

     (Nordic gold
    Nordic gold
    Nordic gold is the alloy from which the middle three denominations of euro coins, 50 cent, 20 cent, and 10 cent coins are made. It has also been in use for a number of years in other countries, most notably in the Swedish 10-krona coin...

    ).
  • Arsenical brass contains an addition of arsenic
    Arsenic
    Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

     and frequently aluminium and is used for boiler fireboxes.
  • Beta brasses, with 45–50% zinc content, can only be worked hot, and are harder, stronger, and suitable for casting.
  • Cartridge brass is a 30% zinc brass with good cold working properties. Used for ammunition cases.
  • Common brass, or rivet brass, is a 37% zinc brass, cheap and standard for cold working.
  • DZR brass is dezincification resistant brass with a small percentage of arsenic.
  • Gilding metal
    Gilding metal
    Gilding metal is a copper alloy, comprising 95% copper and 5% zinc. Technically, it is a brass.Gilding metal is used for various purposes, including the jackets of bullets, driving bands on some artillery shells, as well as enameled badges and other jewellery....

    is the softest type of brass commonly available. An alloy of 95% copper and 5% zinc, gilding metal is typically used for ammunition "jackets", e.g. full metal jacket
    Full metal jacket bullet
    A full metal jacket is a bullet consisting of a soft core encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead...

     bullets.
  • High brass contains 65% copper and 35% zinc, has a high tensile strength
    Tensile strength
    Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...

     and is used for springs
    Spring (device)
    A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...

    , screw
    Screw
    A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...

    s, and rivet
    Rivet
    A rivet is a permanent mechanical fastener. Before being installed a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole, and the tail is upset, or bucked A rivet...

    s.
  • Leaded brass is an alpha-beta brass with an addition of lead
    Lead
    Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

    . It has excellent machinability.
  • Lead-free brass as defined by California Assembly Bill AB 1953 contains "not more than 0.25 percent lead content".
  • Low brass is a copper-zinc alloy containing 20% zinc with a light golden color and excellent ductility; it is used for flexible metal hoses and metal bellows
    Bellows
    A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...

    .
  • Manganese brass is a brass most notably used in making golden dollar coins in the United States. It contains roughly 70% copper, 29% zinc, and 1.3% manganese
    Manganese
    Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

    .
  • Muntz metal
    Muntz metal
    Muntz metal is a form of alpha-beta brass with about 60% copper, 40% zinc and a trace of iron. It is named after George Fredrick Muntz, a metal-roller of Birmingham, England who commercialised the alloy following his patent of 1832....

    is about 60% copper, 40% zinc and a trace of iron, used as a lining on boats.
  • Nickel brass is composed of 70% copper, 24.5% zinc and 5.5% nickel used to make pound coins in the pound sterling currency.
  • Naval brass, similar to admiralty brass, is 40% zinc and 1% tin.
  • Nordic gold
    Nordic gold
    Nordic gold is the alloy from which the middle three denominations of euro coins, 50 cent, 20 cent, and 10 cent coins are made. It has also been in use for a number of years in other countries, most notably in the Swedish 10-krona coin...

    , used in 10, 20 and 50 cts euro coins, contains 89% copper, 5% aluminium, 5% zinc, and 1% tin.
  • Red brass is both an American term for the copper-zinc-tin alloy known as gunmetal
    Gunmetal
    Gunmetal, also known as yellow brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Originally used chiefly for making guns, gunmetal was eventually superseded by steel...

    , and an alloy which is considered both a brass and a bronze. It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc. Red brass is also an alternative name for copper alloy C23000, which is composed of 14–16% zinc, 0.05% iron and lead, and the remainder copper. It may also refer to ounce metal, another copper-zinc-tin alloy.
  • Rich low brass (Tombac
    Tombac
    Tombac, as spelled in French, or Tombak is a brass alloy with high copper content and 5-20% zinc content. Tin, lead or arsenic may be added for colouration.It is a cheap malleable alloy mainly used for medals, ornament, decoration and some munitions....

    ) is 15% zinc. It is often used in jewelry applications.
  • Tonval brass (also called CW617N or CZ122 or OT58) is a copper-lead-zinc alloy. It is not recommended for seawater use, being susceptible to dezincification.
  • White brass contains more than 50% zinc and is too brittle for general use. The term may also refer to certain types of nickel silver
    Nickel silver
    Nickel silver, also known as German silver, Argentann, new silver, nickel brass, albata,, or alpacca, is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. Nickel silver is named for its silvery appearance, but it contains no elemental silver...

     alloys as well as Cu-Zn-Sn alloys with high proportions (typically 40%+) of tin and/or zinc, as well as predominantly zinc casting alloys with copper additive.
  • Yellow brass is an American term for 33% zinc brass.

History


Although forms of brass have been in use since prehistory
Prehistory
Prehistory is the span of time before recorded history. Prehistory can refer to the period of human existence before the availability of those written records with which recorded history begins. More broadly, it refers to all the time preceding human existence and the invention of writing...

, its true nature as a copper-zinc alloy was not understood until the post medieval period because the zinc vapor
Vapor
A vapor or vapour is a substance in the gas phase at a temperature lower than its critical point....

 which reacted with copper to make brass was not recognised as a metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

. The King James Bible makes many references to "brass". The Shakespearean English form of the word 'brass' can mean any bronze alloy, or copper, rather than the strict modern definition of brass. The earliest brasses may have been natural alloys made by smelting
Smelting
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...

 zinc-rich copper ores
Orés
Orés is a municipality in the Cinco Villas, in the province of Zaragoza, in the autonomous community of Aragon, Spain. It belongs to the comarca of Cinco Villas. It is placed 104 km to the northwest of the provincial capital city, Zaragoza. Its coordinates are: 42° 17' N, 1° 00' W, and is...

. By the Roman
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 period brass was being deliberately produced from metallic copper and zinc minerals using the cementation
Calamine brass
Calamine brass is brass produced by a particular alloying technique using the zinc ore calamine directly, rather than first refining it to metallic zinc...

 process and variations on this method continued until the mid 19th century. It was eventually replaced by speltering, the direct alloying of copper and zinc metal which was introduced to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 in the 16th century.

Early copper zinc alloys


In West Asia and the Eastern Mediterranean
Eastern Mediterranean
The Eastern Mediterranean is a term that denotes the countries geographically to the east of the Mediterranean Sea. This region is also known as Greater Syria or the Levant....

 early copper zinc alloys are now known in small numbers from a number of third Millennium BC sites in the Aegean
Aegean Sea
The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...

, Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

, the United Arab Emirates
United Arab Emirates
The United Arab Emirates, abbreviated as the UAE, or shortened to "the Emirates", is a state situated in the southeast of the Arabian Peninsula in Western Asia on the Persian Gulf, bordering Oman, and Saudi Arabia, and sharing sea borders with Iraq, Kuwait, Bahrain, Qatar, and Iran.The UAE is a...

, Kalmikia, Turkmenistan
Turkmenistan
Turkmenistan , formerly also known as Turkmenia is one of the Turkic states in Central Asia. Until 1991, it was a constituent republic of the Soviet Union, the Turkmen Soviet Socialist Republic . Turkmenistan is one of the six independent Turkic states...

 and Georgia
Georgia (country)
Georgia is a sovereign state in the Caucasus region of Eurasia. Located at the crossroads of Western Asia and Eastern Europe, it is bounded to the west by the Black Sea, to the north by Russia, to the southwest by Turkey, to the south by Armenia, and to the southeast by Azerbaijan. The capital of...

 and from 2nd Millennium BC sites in West India
West India
West India or the Western region of India consists of the states of Goa, Gujarat and Maharashtra, along with the Union Territories of Daman and Diu and Dadra and Nagar Haveli. It is highly industrialized, with a large urban population. Most of Western India was part of the Maratha Empire before...

, Uzbekistan
Uzbekistan
Uzbekistan , officially the Republic of Uzbekistan is a doubly landlocked country in Central Asia and one of the six independent Turkic states. It shares borders with Kazakhstan to the west and to the north, Kyrgyzstan and Tajikistan to the east, and Afghanistan and Turkmenistan to the south....

, Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

, Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....

, Iraq and Palestine
Palestine
Palestine is a conventional name, among others, used to describe the geographic region between the Mediterranean Sea and the Jordan River, and various adjoining lands....

. However, isolated examples of copper-zinc alloys are known in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 from as early as the 5th Millennium BC.

The compositions of these early "brass" objects are very variable and most have zinc contents of between 5% and 15% wt which is lower than in brass produced by cementation. These may be "natural alloys" manufactured by smelting zinc rich copper ores in reducing conditions. Many have similar tin contents to contemporary bronze artefacts
Artifact (archaeology)
An artifact or artefact is "something made or given shape by man, such as a tool or a work of art, esp an object of archaeological interest"...

 and it is possible that some copper-zinc alloys were accidental and perhaps not even distinguished from copper. However the large number of copper-zinc alloys now known suggests that at least some were deliberately manufactured and many have zinc contents of more than 12% wt which would have resulted in a distinctive golden color.

By the 8th–7th century BC Assyria
Assyria
Assyria was a Semitic Akkadian kingdom, extant as a nation state from the mid–23rd century BC to 608 BC centred on the Upper Tigris river, in northern Mesopotamia , that came to rule regional empires a number of times through history. It was named for its original capital, the ancient city of Assur...

n cuneiform
Cuneiform
Cuneiform can refer to:*Cuneiform script, an ancient writing system originating in Mesopotamia in the 4th millennium BC*Cuneiform , three bones in the human foot*Cuneiform Records, a music record label...

 tablets mention the exploitation of the "copper of the mountains" and this may refer to "natural" brass. Oreichalkos, the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 translation of this term, was later adapted to the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 aurichalcum meaning "golden copper" which became the standard term for brass. In the 4th century BC Plato
Plato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

 knew oreichalkos as rare and nearly as valuable as gold and Pliny
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

 describes how aurichalcum had come from Cypriot
Cyprus
Cyprus , officially the Republic of Cyprus , is a Eurasian island country, member of the European Union, in the Eastern Mediterranean, east of Greece, south of Turkey, west of Syria and north of Egypt. It is the third largest island in the Mediterranean Sea.The earliest known human activity on the...

 ore deposits which had been exhausted by the 1st century AD.

Brass making in the Roman World


During the later part of first Millennium BC the use of brass spread across a wide geographical area from Britain
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 and Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 in the west to Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

, and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 in the east. This seems to have been encouraged by exports and influence from the Middle-East and eastern Mediterranean where deliberate production of brass from metallic copper and zinc ores had been introduced. The 4th century BC writer Theopompus
Theopompus
Theopompus was a Greek historian and rhetorician- Biography :Theopompus was born on Chios. In early youth he seems to have spent some time at Athens, along with his father, who had been exiled on account of his Laconian sympathies...

, quoted by Strabo
Strabo
Strabo, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...

, describes how heating earth from Andeira in Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 produced "droplets of false silver", probably metallic zinc, which could be used to turn copper into oreichalkos. In the 1st century BC the Greek Dioscorides seems to have recognised a link between zinc minerals and brass describing how Cadmia
Cadmia
In alchemy, cadmia , is an oxide of zinc which collects on the sides of furnaces where copper or brass was smelted, and zinc sublimed...

 (zinc oxide
Zinc oxide
Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...

) was found on the walls of furnaces used to heat either zinc ore or brass and explaining that it can then be used to make brass.

By the first century BC brass was available in sufficient supply to use as coin
Coin
A coin is a piece of hard material that is standardized in weight, is produced in large quantities in order to facilitate trade, and primarily can be used as a legal tender token for commerce in the designated country, region, or territory....

age in Phrygia
Phrygia
In antiquity, Phrygia was a kingdom in the west central part of Anatolia, in what is now modern-day Turkey. The Phrygians initially lived in the southern Balkans; according to Herodotus, under the name of Bryges , changing it to Phruges after their final migration to Anatolia, via the...

 and Bithynia
Bithynia
Bithynia was an ancient region, kingdom and Roman province in the northwest of Asia Minor, adjoining the Propontis, the Thracian Bosporus and the Euxine .-Description:...

, and after the Augustan currency reform of 23 BC it was also used to make Roman dupondii
Dupondius
The dupondius was a brass coin used during the Roman Empire and Roman Republic valued at 2 asses ....

and sestertii. The uniform use of brass for coinage and military equipment across the Roman world may indicate a degree of state involvement in the industry, and brass even seems to have been deliberately boycotted by Jewish communities in Palestine because of its association with Roman authority.

Brass was produced by the cementation process where copper and zinc ore are heated together until zinc vapor is produced which reacts with the copper. There is good archaeological evidence for this process and crucibles used to produce brass by cementation have been found on Roman period sites including Xanten
Xanten
Xanten is a historic town in the North Rhine-Westphalia state of Germany, located in the district of Wesel.Xanten is known for the Archaeological Park or archaeological open air museum , its medieval picturesque city centre with Xanten Cathedral and many museums, its large man-made lake for...

 and Nidda in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Lyon
Lyon
Lyon , is a city in east-central France in the Rhône-Alpes region, situated between Paris and Marseille. Lyon is located at from Paris, from Marseille, from Geneva, from Turin, and from Barcelona. The residents of the city are called Lyonnais....

 in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 and at a number of sites in Britain. They vary in size from tiny acorn sized to large amphorae like vessels but all have elevated levels of zinc on the interior and are lidded. They show no signs of slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...

 or metal prills suggesting that zinc minerals were heated to produce zinc vapor which reacted with metallic copper in a solid state reaction. The fabric of these crucibles is porous, probably designed to prevent a build up of pressure, and many have small holes in the lids which may be designed to release pressure or to add additional zinc minerals near the end of the process. Dioscorides mentioned that zinc minerals were used for both the working and finishing of brass, perhaps suggesting secondary additions.

Brass made during the early Roman period seems to have varied between 20% to 28% wt zinc. The high content of zinc in coinage and brass objects declined after the first century AD and it has been suggested that this reflects zinc loss during recycling
Recycling
Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...

 and thus an interruption in the production of new brass. However it is now thought this was probably a deliberate change in composition and overall the use of brass increases over this period making up around 40% of all copper alloys
Copper alloys
Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead...

 used in the Roman world by the 4th century AD.

Brass making in the medieval period



Little is known about the production of brass during the centuries immediately after the collapse of the Roman Empire
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

. Disruption in the trade of tin for bronze from Western Europe
Western Europe
Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

 may have contributed to the increasing popularity of brass in the east and by the 6th–7th centuries AD over 90% of copper alloy artefacts from Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

 were made of brass. However other alloys such as low tin bronze were also used and they vary depending on local cultural attitudes, the purpose of the metal and access to zinc, especially between the Islamic and Byzantine
Byzantine
Byzantine usually refers to the Roman Empire during the Middle Ages.Byzantine may also refer to:* A citizen of the Byzantine Empire, or native Greek during the Middle Ages...

 world. Conversely the use of true brass seems to have declined in Western Europe during this period in favour of gunmetal
Gunmetal
Gunmetal, also known as yellow brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Originally used chiefly for making guns, gunmetal was eventually superseded by steel...

s and other mixed alloys but by the end of the first Millennium AD brass artefacts are found in Scandinavian
Scandinavians
Scandinavians are a group of Germanic peoples, inhabiting Scandinavia and to a lesser extent countries associated with Scandinavia, and speaking Scandinavian languages. The group includes Danes, Norwegians and Swedes, and additionally the descendants of Scandinavian settlers such as the Icelandic...

 graves in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

, brass was being used in the manufacture of coins in Northumbria
Northumbria
Northumbria was a medieval kingdom of the Angles, in what is now Northern England and South-East Scotland, becoming subsequently an earldom in a united Anglo-Saxon kingdom of England. The name reflects the approximate southern limit to the kingdom's territory, the Humber Estuary.Northumbria was...

 and there is archaeological and historical evidence for the production of brass in Germany and The Low Countries areas rich in calamine
Calamine
Calamine is a mixture of zinc oxide with about 0.5% ferric oxide . It is the main ingredient in calamine lotion and is used as an antipruritic to treat mild pruritic conditions such as sunburn, eczema, rashes, poison ivy, chickenpox, and insect bites and stings...

 ore which would remain important centres of brass making throughout the medieval period, especially Dinant
Dinant
Dinant is a Walloon city and municipality located on the River Meuse in the Belgian province of Namur, Belgium. The Dinant municipality includes the old communes of Anseremme, Bouvignes-sur-Meuse, Dréhance, Falmagne, Falmignoul, Foy-Notre-Dame, Furfooz, Lisogne, Sorinnes, and Thynes.-Origins to...

 – brass objects are still collectively known as dinanterie in French. The Baptismal font at St Bartholomew's Church, Liège in modern Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

 (before 1117) is an outstanding masterpiece of Romanesque
Romanesque art
Romanesque art refers to the art of Western Europe from approximately 1000 AD to the rise of the Gothic style in the 13th century, or later, depending on region. The preceding period is increasingly known as the Pre-Romanesque...

 brass casting.

The cementation process continued to be used but literary sources from both Europe and the Islamic world seem to describe variants of a higher temperature liquid process which took places in open topped crucibles. Islamic cementation seems to have used zinc oxide known as tutiya or tutty rather than zinc ores for brass making resulting in a metal with lower iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 impurities. A number of Islamic writers and the 13th century Italian Marco Polo
Marco Polo
Marco Polo was a Venetian merchant traveler from the Venetian Republic whose travels are recorded in Il Milione, a book which did much to introduce Europeans to Central Asia and China. He learned about trading whilst his father and uncle, Niccolò and Maffeo, travelled through Asia and apparently...

 describe how this was obtained by sublimation from zinc ores and condensed
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

 onto clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 or iron bars, archaeological examples of which have been identified at Kush
Hindu Kush
The Hindu Kush is an mountain range that stretches between central Afghanistan and northern Pakistan. The highest point in the Hindu Kush is Tirich Mir in the Chitral region of Khyber-Pakhtunkhwa, Pakistan.It is the westernmost extension of the Pamir Mountains, the Karakoram Range, and is a...

 in Iran. It could then be used for brass making or medicinal purposes. In 10th century Yemen
Yemen
The Republic of Yemen , commonly known as Yemen , is a country located in the Middle East, occupying the southwestern to southern end of the Arabian Peninsula. It is bordered by Saudi Arabia to the north, the Red Sea to the west, and Oman to the east....

 al-Hamdani described how spreading al-iglimiya, probably zinc oxide, onto the surface of molten copper produced tutiya vapor which then reacted with the metal. The 13th century Iranian writer al-Kashani describes a more complex process whereby tutiya was mixed with raisins and gently roasted before being added to the surface of the molten metal. A temporary lid was added at this point presumably to minimise the escape of zinc vapor.

In Europe a similar liquid process in open topped crucibles took place which was probably less efficient than the Roman process and the use of the term tutty by Albertus Magnus
Albertus Magnus
Albertus Magnus, O.P. , also known as Albert the Great and Albert of Cologne, is a Catholic saint. He was a German Dominican friar and a bishop, who achieved fame for his comprehensive knowledge of and advocacy for the peaceful coexistence of science and religion. Those such as James A. Weisheipl...

 in the 13th century suggests influence from Islamic technology. The 12th century German
Germans
The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

 monk Theophilus
Theophilus Presbyter
Theophilus Presbyter is the pseudonymous author or compiler ofa Latin text containing detailed descriptions of various medieval arts, a text commonly known as the Schedula diversarum artium or De diversis artibus , probably first compiled between 1100 and 1120...

 described how preheated crucibles were one sixth filled with powdered calamine and charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 then topped up with copper and charcoal before being melted, stirred then filled again. The final product was cast
Casting
In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...

, then again melted with calamine. It has been suggested that this second melting may have taken place at a lower temperature to allow more zinc to be absorbed. Albertus Magnus noted that the "power" of both calamine and tutty could evaporate and described how the addition of powdered glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

 could create a film to bind it to the metal.
German brass making crucibles are known from Dortmund
Dortmund
Dortmund is a city in Germany. It is located in the Bundesland of North Rhine-Westphalia, in the Ruhr area. Its population of 585,045 makes it the 7th largest city in Germany and the 34th largest in the European Union....

 dating to the 10th century AD and from Soest
Soest, Germany
Soest is a town in North Rhine-Westphalia, Germany. It is the capital of the Soest district. After Lippstadt, a neighbouring town, Soest is the second biggest town in its district.-Geography:...

 and Schwerte
Schwerte
Schwerte is a town in the district of Unna, in North Rhine-Westphalia, Germany.-Geography:Schwerte is situated in the Ruhr valley, at the south-east border of the Ruhr Area...

 in Westphalia
Westphalia
Westphalia is a region in Germany, centred on the cities of Arnsberg, Bielefeld, Dortmund, Minden and Münster.Westphalia is roughly the region between the rivers Rhine and Weser, located north and south of the Ruhr River. No exact definition of borders can be given, because the name "Westphalia"...

 dating to around the 13th century confirm Theophilus' account as they are open topped, although ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

 discs from Soest may have served as loose lids which may have been used to reduce zinc evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

, and have slag on the interior resulting from a liquid process.

Brass making in Renaissance and post medieval Europe


The Renaissance
Renaissance
The Renaissance was a cultural movement that spanned roughly the 14th to the 17th century, beginning in Italy in the Late Middle Ages and later spreading to the rest of Europe. The term is also used more loosely to refer to the historical era, but since the changes of the Renaissance were not...

 saw important changes to both the theory and practice of brassmaking in Europe. By the 15th century there is evidence for the renewed use of lidded cementation crucibles at Zwickau
Zwickau
Zwickau in Germany, former seat of the government of the south-western region of the Free State of Saxony, belongs to an industrial and economical core region. Nowadays it is the capital city of the district of Zwickau...

 in Germany. These large crucibles were capable of producing c.20 kg of brass. There are traces of slag and pieces of metal on the interior. Their irregular composition suggesting that this was a lower temperature not entirely liquid process. The crucible lids had small holes which were blocked with clay plugs near the end of the process presumably to maximise zinc absorption in the final stages. Triangular crucibles were then used to melt the brass for casting
Casting
In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...

.

16th century technical writers such as Biringuccio, Ercker and Agricola
Georg Agricola
Georgius Agricola was a German scholar and scientist. Known as "the father of mineralogy", he was born at Glauchau in Saxony. His real name was Georg Pawer; Agricola is the Latinised version of his name, Pawer meaning "farmer"...

 described a variety of cementation brass making techniques and came closer to understanding the true nature of the process noting that copper became heavier as it changed to brass and that it became more golden as additional calamine was added. Zinc metal was also becoming more commonplace By 1513 metallic zinc ingots from India and China were arriving in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 and pellets of zinc condensed in furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...

 flues at the Rammelsberg in Germany were exploited for cementation brass making from around 1550.

Eventually it was discovered that metallic zinc could be alloyed with copper to make brass; a process known as speltering and by 1657 the German chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

 Johann Glauber had recognised that calamine was "nothing else but unmeltable zinc" and that zinc was a "half ripe metal." However some earlier high zinc, low iron brasses such as the 1530 Wightman brass memorial plaque
Commemorative plaque
A commemorative plaque, or simply plaque, is a plate of metal, ceramic, stone, wood, or other material, typically attached to a wall, stone, or other vertical surface, and bearing text in memory of an important figure or event...

 from England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 may have been made by alloying copper with zinc and include traces of cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...

 similar those found in some zinc ingots from China.

However the cementation process was not abandoned and as late as the early 19th century there are descriptions of solid state
Solid-state chemistry
Solid-state chemistry, also sometimes referred to as materials chemistry, is the study of the synthesis, structure, and properties of solid phase materials, particularly, but not necessarily exclusively of, non-molecular solids...

 cementation in a domed furnace at around 900–950 degrees Celsius and lasting up to 10 hours. The European brass industry continued to flourish into the post medieval period buoyed by innovations such as the 16th century introduction of water powered hammers for the production of battery wares. By 1559 the Germany city of Aachen
Aachen
Aachen has historically been a spa town in North Rhine-Westphalia, Germany. Aachen was a favoured residence of Charlemagne, and the place of coronation of the Kings of Germany. Geographically, Aachen is the westernmost town of Germany, located along its borders with Belgium and the Netherlands, ...

 alone was capable of producing 300,000 cwt of brass per year. After several false starts during the 16th and 17th centuries the brass industry was also established in England taking advantage of abundant supplies of cheap copper smelted in the new coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 fired reverberatory furnace
Reverberatory furnace
A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases...

. In 1723 Bristol
Bristol
Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...

 brass maker Nehemiah Champion patented the use of granulated copper, produced by pouring molten metal into cold water. This increased the surface area
Surface area
Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra the surface area is the sum of the areas of its faces...

 of the copper helping it react and zinc contents of up to 33% wt were reported using this new technique.

In 1738 Nehemiah's son William Champion
William Champion (metallurgist)
William Champion is credited with patenting a process in Great Britain to distill zinc from calamine using charcoal in a smelter.Champion came from a family who were already concerned in the metal trade at Bristol, his father being a leading partner in the Bristol Brass Company. As a young man he...

 patented a technique for the first industrial scale distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

 of metallic zinc known as distillation per descencum or "the English process." This local zinc was used in speltering and allowed greater control over the zinc content of brass and the production of high zinc copper alloys which would have been difficult or impossible to produce using cementation, for use in expensive objects such as scientific instruments, clocks, brass buttons and costume jewellery. However Champion continued to use the cheaper calamine cementation method to produce lower zinc brass and the archaeological remains of bee-hive shaped cementation furnaces have been identified at his works at Warmley
Warmley
Warmley is a village in South Gloucestershire, England, to the east of Kingswood on the outskirts of Bristol.In the mid 18th century it contained the Warmley Works of William Champion...

. By the mid late 18th century developments in cheaper zinc distillation such as John-Jaques Dony's horizontal furnaces in Belgium and the reduction of tariffs on zinc as well as demand for corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...

resistant high zinc alloys increased the popularity of speltering and as a result cementation was largely abandoned by the mid 19th century.