Editing Lead (section)

== Applications ==
[[File:Lead shielding.jpg|thumb|left|Bricks of lead (alloyed with 4% antimony) are used as radiation shielding.{{sfn|Street|Alexander|1998|p=181}}|alt=A closed structure of black bricks]]

Contrary to popular belief, pencil leads in wooden pencils have never been made from lead. When the pencil originated as a wrapped graphite writing tool, the particular type of [[graphite]] used was named ''[[Graphite|plumbago]]'' (literally, ''lead mockup'').{{sfn|Evans|1908|pp=133–179}}

=== Elemental form ===
Lead metal has several useful mechanical properties, including high density, low melting point, ductility, and relative inertness. Many metals are superior to lead in some of these aspects but are generally less common and more difficult to extract from parent ores. Lead's toxicity has led to its phasing out for some uses.{{sfn|Baird|Cann|2012|pp=537–538, 543–547}}

Lead has been used for bullets since their invention in the Middle Ages. It is inexpensive; its low melting point means small arms ammunition and shotgun pellets can be cast with minimal technical equipment; and it is denser than other common metals, which allows for better retention of velocity. It remains the main material for bullets, alloyed with other metals as hardeners.{{sfn|Ramage|1980|p=8}} Concerns have been raised that lead bullets used for hunting can damage the environment.{{efn|California began banning lead bullets for hunting on that basis in July 2015.{{sfn|California Department of Fish and Wildlife}}}} [[Shotgun]] [[Shotgun cartridge|cartridges]] used for [[waterfowl hunting]] must today be lead-free in the [[United States]],<ref>{{Cite web |date=2022-04-19 |title=Nontoxic Shot Regulations For Hunting Waterfowl and Coots in the U.S. {{!}} U.S. Fish & Wildlife Service |url=https://www.fws.gov/story/2022-04/nontoxic-shot-regulations-hunting-waterfowl-and-coots-us |access-date=2024-09-12 |website=www.fws.gov |language=en}}</ref> [[Canada]],<ref>{{Cite web |last=Canada |first=Environment and Climate Change |date=2018-04-05 |title=Moving towards using more lead-free ammunition |url=https://www.canada.ca/en/environment-climate-change/services/management-toxic-substances/list-canadian-environmental-protection-act/lead/using-more-lead-free-ammunition.html |access-date=2024-09-12 |website=www.canada.ca}}</ref> and in [[Europe]].<ref>{{Cite web |title=Regulation - 2021/57 - EN - EUR-Lex |url=https://eur-lex.europa.eu/eli/reg/2021/57/oj |access-date=2024-09-12 |website=eur-lex.europa.eu |language=en}}</ref>

Lead's high density and resistance to corrosion have been exploited in a number of related applications. It is used as [[ballast]] in sailboat keels; its density allows it to take up a small volume and minimize water resistance, thus counterbalancing the heeling effect of wind on the sails.{{sfn|Parker|2005|pp=194–195}} It is used in [[scuba diving]] [[diving weighting system|weight belts]] to counteract the diver's buoyancy.{{sfn|Krestovnikoff|Halls|2006|p=70}} In 1993, the base of the [[Leaning Tower of Pisa]] was stabilized with 600 tonnes of lead.{{sfn|Street|Alexander|1998|p=182}} Because of its corrosion resistance, lead is used as a protective sheath for underwater cables.{{sfn|Jensen|2013|p=136}}

[[File:Parc de Versailles, Bassin de Flore, Jean-Baptiste Tuby (1672-79) 07.jpg|right|thumb|alt=Yellow sculpture|A 17th-century gold-coated lead sculpture]]
Lead has many uses in the construction industry; lead sheets are used as [[architectural metals]] in [[Domestic roof construction|roofing material]], [[Cladding (construction)|cladding]], [[Flashing (weatherproofing)|flashing]], [[rain gutter|gutters]] and gutter joints, roof parapets.{{sfn|Think Lead research}}{{sfn|Weatherings to Parapets}} Lead is still used in statues and sculptures,{{efn|For example, a firm "...producing quality [lead] garden ornament from our studio in West London for over a century".{{sfn|Lead garden ornaments|2016}}}} including for [[armature (sculpture)|armatures]].{{sfn|Putnam|2003|p=216}} In the past it was often used to [[tire balance|balance the wheels of cars]]; for environmental reasons this use is being phased out in favor of other materials.{{sfn|United States Geological Survey|2017|p=97}}

Lead is added to copper alloys, such as [[brass]] and [[bronze]], to improve machinability and for its lubricating qualities. Being practically insoluble in copper, the lead forms solid globules in imperfections throughout the alloy, such as [[Grain boundary|grain boundaries]]. In low concentrations, as well as acting as a lubricant, the globules hinder the formation of [[swarf]] as the alloy is worked, thereby improving machinability. Copper alloys with larger concentrations of lead are used in [[Bearing (mechanical)|bearings]]. The lead provides lubrication, and the copper provides the load-bearing support.{{sfn|Copper Development Association}}

Lead's high density, atomic number, and formability form the basis for use of lead as a barrier that absorbs sound, vibration, and radiation.{{sfn|Rich|1994|p=101}} Lead has no natural resonance frequencies;{{sfn|Rich|1994|p=101}} as a result, sheet-lead is used as a sound deadening layer in the walls, floors, and ceilings of sound studios.{{sfn|Guruswamy|2000|p=31}} [[Organ pipe]]s are often made from a lead alloy, mixed with various amounts of tin to control the tone of each pipe.{{sfn|Audsley|1965|pp=250–251}}{{sfn|Palmieri|2006|pp=412–413}} Lead is an established [[lead shielding|shielding]] material from [[ionizing radiation|radiation]] in nuclear science and in X-ray rooms{{sfn|National Council on Radiation Protection and Measurements|2004|p=16}} due to its denseness and high [[attenuation coefficient]].{{sfn|Thornton|Rautiu|Brush|2001|p=7}} Molten lead has been used as a coolant for [[lead-cooled fast reactor]]s.{{sfn|Tuček|Carlsson|Wider|2006|p=1590}}

=== Batteries ===
The largest use of lead in the early 21st century is in [[Lead-acid battery|lead–acid batteries]]. The lead in batteries undergoes no direct contact with humans, so there are fewer toxicity concerns.{{efn|Potential injuries to regular users of such batteries are not related to lead's toxicity.{{sfn|Concordia University|2016}}}} People who work in lead battery production or recycling plants may be exposed to lead dust and inhale it.{{sfn|Toxicological Profile for Lead|2007|pp=5–6}} The reactions in the battery between lead, lead dioxide, and sulfuric acid provide a reliable source of [[voltage]].{{efn|See{{sfn|Progressive Dynamics, Inc.}} for details on how a lead–acid battery works.}} [[Supercapacitor]]s incorporating lead–acid batteries have been installed in kilowatt and megawatt scale applications in Australia, Japan, and the United States in frequency regulation, solar smoothing and shifting, wind smoothing, and other applications.{{sfn|Olinsky-Paul|2013}} These batteries have lower energy density and charge-discharge efficiency than [[lithium-ion battery|lithium-ion batteries]], but are significantly cheaper.{{sfn|Gulbinska|2014}}

=== Coating for cables ===
Lead is used in high voltage power cables as shell material to prevent water diffusion into insulation; this use is decreasing as lead is being phased out.{{sfn|Rich|1994|pp=133–134}} Its use in [[solder]] for electronics is also being phased out by some countries to reduce the amount of [[environmental hazard|environmentally hazardous]] waste.{{sfn|Zhao|2008|p=440}} Lead is one of three metals used in the [[Oddy test]] for museum materials, helping detect organic acids, aldehydes, acidic gases.{{sfn|Beiner|Lavi|Seri|Rossin|2015}}{{sfn|Szczepanowska|2013|pp=84–85}}

=== Compounds ===
[[File:Crystal_glass.jpg|thumb|[[Lead glass]]|alt=A crystal glass|left]]
[[File:PbCrO4 and PbCrO4•PbO.jpg|thumb|upright|[[Lead(II) chromate|Lead yellow]] and [[Lead(II,IV) oxide|lead red]]|right]]

In addition to being the main application for lead metal, lead–acid batteries are also the main consumer of lead compounds. The energy storage/release reaction used in these devices involves [[Lead(II) sulfate|lead sulfate]] and [[lead dioxide]]:{{Citation needed|date=April 2025}}
:{{chem|Pb}}(s) + {{chem|PbO|2}}(s) + 2{{chem|H|2|SO|4}}(aq) → 2{{chem|PbSO|4}}(s) + 2{{chem|H|2|O}}(l)

Other applications of lead compounds are very specialized and often fading. Lead-based coloring agents are used in [[ceramic glaze]]s and glass, especially for red and yellow shades.{{sfn|Burleson|2001|p=23}} While lead paints are phased out in Europe and North America, they remain in use in less developed countries such as China,{{sfn|Insight Explorer|IPEN|2016}} India,{{sfn|Singh|2017}} or Indonesia.{{sfn|Ismawati|Primanti|Brosché|Clark|2013|p=2}} Lead tetraacetate and lead dioxide are used as oxidizing agents in organic chemistry. Lead is frequently used in the [[polyvinyl chloride]] coating of electrical cords.{{sfn|Zweifel|2009|page=438}}{{sfn|Wilkes|Summers|Daniels|Berard|2005|p=106}} It can be used to treat candle wicks to ensure a longer, more even burn. Because of its toxicity, European and North American manufacturers use alternatives such as zinc.{{sfn|Randerson|2002}}{{sfn|Nriagu|Kim|2000|pp=37–41}} [[Lead glass]] is composed of 12–28% [[Lead(II) oxide|lead oxide]], changing its optical characteristics and reducing the transmission of ionizing radiation,{{sfn|Amstock|1997|pp=116–119}} a property used in old TVs and computer monitors with [[cathode-ray tube]]s. Lead-based [[semiconductor]]s such as [[lead telluride]] and [[lead selenide]] are used in [[Photovoltaics|photovoltaic]] cells and [[infrared]] detectors.{{sfn|Rogalski|2010|pp=485–541}}