{
  "spore": "profile",
  "id": "woods-metal",
  "spore_version": "0.2",
  "family": "low-melting-metals-and-solders",
  "name": "Wood's metal",
  "abbreviation": "-",
  "role": "low-melting fusible alloy (about 70 °C, bismuth-lead-tin-cadmium)",
  "category": "metals",
  "type": "heavy-metals",
  "summary": "Wood's metal is a eutectic alloy of bismuth, lead, tin and cadmium, named for Barnabas Wood, who patented it in 1860. Wikipedia gives its nominal composition as 50% bismuth, 26.7% lead, 13.3% tin and 10% cadmium by mass, and a melting point of approximately 70 °C (158 °F). A 1989 measurement paper on an industrial Wood alloy gives a solidification temperature of 343 K and a density of 10.15 g/cm3 on solidification, for a composition with more lead than the nominal alloy. Its room-temperature modulus of elasticity is 12.7 GPa and yield strength is 26.2 MPa, both as stated by Wikipedia. The alloy contains lead and cadmium, and the sources read say its fumes are toxic and skin contact is harmful.\n",
  "best_for": "Low-melting fusible links, plugs and holding fixtures, where the alloy must melt near 70 °C (Wikipedia lists fusible links in sprinkler heads and fusible plugs in boilers)",
  "weakest_at": "Toxicity: it contains cadmium and lead, and the sources read call its fumes toxic. Few physical data were found: no thermal conductivity, specific heat or corrosion value for the alloy was found in any source read",
  "identity": {
    "formula": "Bi-Pb-Sn-Cd eutectic alloy, nominal 50% Bi, 26.7% Pb, 13.3% Sn, 10% Cd by mass",
    "designations": [],
    "source": "wikipedia-woods-metal",
    "where": "Lead section, composition sentence (eutectic alloy of 50% bismuth, 26.7% lead, 13.3% tin and 10% cadmium by mass)"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "thermal-control",
      "radiation-shielding",
      "mechanisms"
    ]
  },
  "properties": [
    {
      "benchmark": "melting_point",
      "label": "Melting point of Wood's metal (eutectic composition)",
      "value": 70,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "composition": "eutectic, 50% Bi, 26.7% Pb, 13.3% Sn, 10% Cd by mass (as the source gives it)",
        "basis": "stated as approximately 70 °C (158 °F)"
      },
      "method": "Approximate value in the lead section of an encyclopedia article (secondary source, underlying measurement not named)",
      "status": "ground",
      "source": "wikipedia-woods-metal",
      "where": "Lead section, first paragraph (\"approximately 70 °C (158 °F)\")",
      "source_detail": {
        "title": "Wood's metal, Wikipedia (lead section, applications section, toxicity section)",
        "url": "https://en.wikipedia.org/wiki/Wood%27s_metal",
        "kind": "web",
        "license": "CC BY-SA 4.0, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Solidification temperature of an industrial Wood alloy (1989 measurement)",
      "value": 343,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "composition": "industrial Wood alloy as analysed in the paper: Bi 39.3 to 40.2, Cd and Sn 8.85 to 9.75, Pb 40.3 to 41.2 (mass %)",
        "basis": "solidification temperature of the alloy, printed in kelvin"
      },
      "method": "Value stated in the introduction of an experimental measurement paper (Kazandzhan et al., 1989, Russian; full text read)",
      "status": "ground",
      "note": "The composition is not the nominal 50/26.7/13.3/10 alloy. The paper notes that lead content in sources it reviewed ranges from 10 to 42 mass %. 343 K is 70 °C.",
      "source": "kazandzhan1989",
      "where": "Introduction, paragraph after the composition list (solidification temperature of the alloy 343 K)",
      "source_detail": {
        "title": "Experimental study of the electrical conductivity, density and viscosity of a wood alloy (Kazandzhan, Matveev, Savich, Umarov; Teplofizika vysokikh temperatur 27:2, 1989, Russian)",
        "id": "Teplofizika vysokikh temperatur 27:2, pp. 269-273, paper 3860 (mathnet.ru)",
        "url": "https://www.mathnet.ru/php/getFT.phtml?jrnid=tvt&paperid=3860&what=fullt&option_lang=eng",
        "kind": "paper",
        "license": "journal page, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of an industrial Wood alloy on solidification (1989 measurement)",
      "value": 10.15,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "composition": "same industrial alloy as the solidification temperature above (Pb 40.3 to 41.2 mass %)",
        "state": "solid, on solidification (about 343 K)"
      },
      "method": "Density measured on samples: liquid by pycnometer, solid by hydrostatic weighing in distilled water (as described in the paper)",
      "status": "ground",
      "note": "The paper gives linear equations for the liquid and solid density, not a single room-temperature value. The vendor density of 9.7 g/cm3 at 20 °C was seen only in a search result and was not read on a fetched page, so it is not recorded.",
      "source": "kazandzhan1989",
      "where": "Density section, text on the solid state (density rises on solidification to 10,15 g/cm3)",
      "source_detail": {
        "title": "Experimental study of the electrical conductivity, density and viscosity of a wood alloy (Kazandzhan, Matveev, Savich, Umarov; Teplofizika vysokikh temperatur 27:2, 1989, Russian)",
        "id": "Teplofizika vysokikh temperatur 27:2, pp. 269-273, paper 3860 (mathnet.ru)",
        "url": "https://www.mathnet.ru/php/getFT.phtml?jrnid=tvt&paperid=3860&what=fullt&option_lang=eng",
        "kind": "paper",
        "license": "journal page, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of Cerrobend, a bismuth-base eutectic",
      "value": 70,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "Cerrobend is described as a bismuth-base eutectic alloy; the Wikipedia fusible-alloy table lists Wood's metal as exactly the same as Cerrobend"
      },
      "method": "Value in the abstract of an ASM Alloy Digest entry for Cerrobend (the full datasheet is paywalled; the abstract was read)",
      "status": "ground",
      "source": "asm-cerrobend",
      "where": "Abstract, first sentence (\"melts at 158 F (70 C)\")",
      "source_detail": {
        "title": "ASM Alloy Digest, CERROBEND Alloy, low-melting controlled shrinkage (Bi-6)",
        "id": "ASM Alloy Digest, abstract only (full datasheet paywalled)",
        "url": "https://dl.asminternational.org/alloy-digest/article/27/8/Bi-6/4286/CERROBEND-AlloyLow-Melting-Controlled-Shrinkage",
        "kind": "datasheet",
        "license": "ASM, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Modulus of elasticity of Wood's metal at room temperature",
      "value": 12.7,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "room temperature",
        "form": "not stated"
      },
      "method": "Stated in the applications section of an encyclopedia article (underlying test not named)",
      "status": "ground",
      "source": "wikipedia-woods-metal",
      "where": "Applications section, sentence on room-temperature modulus of elasticity (12.7 GPa)",
      "source_detail": {
        "title": "Wood's metal, Wikipedia (lead section, applications section, toxicity section)",
        "url": "https://en.wikipedia.org/wiki/Wood%27s_metal",
        "kind": "web",
        "license": "CC BY-SA 4.0, linked not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength of Wood's metal at room temperature",
      "value": 26.2,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "room temperature",
        "form": "not stated"
      },
      "method": "Stated in the applications section of an encyclopedia article (underlying test not named)",
      "status": "ground",
      "source": "wikipedia-woods-metal",
      "where": "Applications section, sentence on room-temperature yield strength (26.2 MPa)",
      "source_detail": {
        "title": "Wood's metal, Wikipedia (lead section, applications section, toxicity section)",
        "url": "https://en.wikipedia.org/wiki/Wood%27s_metal",
        "kind": "web",
        "license": "CC BY-SA 4.0, linked not reproduced"
      }
    }
  ],
  "corrosion": [],
  "risks": {
    "hazards": [
      {
        "text": "PubChem reports ECHA notifications for elemental cadmium (855 company reports from 40 notifications): H330 (92.2%), H341 (92.2%), H350 (92.2%), H361 (75.6%), and STOT RE 1 (92.2%), which is the H372 category. Chronic aquatic 1 is notified at 100%. Signal word Danger. Wood's metal contains 10% cadmium, so these are hazards of its cadmium content.",
        "ghs": [
          "H330",
          "H341",
          "H350",
          "H361",
          "H372",
          "H410"
        ],
        "source": "pubchem-cadmium",
        "where": "GHS Classification section, aggregated ECHA entry and Hazard Classes and Categories line"
      },
      {
        "text": "PubChem reports ECHA notifications for elemental lead (2,477 company reports from 93 notifications): H360 (84.4%) may damage fertility or the unborn child, H362 (44.3%) and H372 (50.5%). Wood's metal contains 26.7% lead.",
        "ghs": [
          "H360",
          "H362",
          "H372"
        ],
        "source": "pubchem-lead",
        "where": "GHS Classification section, aggregated ECHA entry (CID 5352425)"
      },
      {
        "text": "PubChem reports ECHA notifications for elemental tin (953 company reports): 72.9% (695 of 953) say the substance does not meet GHS criteria. Where codes were given, H319 (24.2%) causes serious eye irritation and H335 (23.1%) may cause respiratory irritation. Wood's metal contains 13.3% tin.",
        "ghs": [
          "H319",
          "H335"
        ],
        "source": "pubchem-tin",
        "where": "GHS Classification section, aggregated ECHA entry (CID 5352426)"
      },
      {
        "text": "Wikipedia says Wood's metal is toxic because it contains lead and cadmium, that its fumes are toxic and that contamination of bare skin is considered harmful. It also says vapour from cadmium-containing alloys is a danger to humans.",
        "ghs": [],
        "source": "wikipedia-woods-metal",
        "where": "Toxicity section and lead section"
      },
      {
        "text": "Wikipedia says elemental bismuth has unusually low toxicity for a heavy metal.",
        "ghs": [],
        "source": "wikipedia-bismuth",
        "where": "Lead section, introduction"
      }
    ],
    "failure_risks": [
      {
        "mode": "Melting at low temperature",
        "trigger": "Temperature at or above about 70 °C",
        "consequence": "The alloy melts. The room-temperature modulus (12.7 GPa) and yield strength (26.2 MPa) do not apply above the melting point. Melting is the intended action in fusible links and plugs.",
        "severity": "moderate",
        "source": "wikipedia-woods-metal",
        "where": "Lead section (melting point) and Applications section (room-temperature values)"
      },
      {
        "mode": "Release of toxic fume or dust",
        "trigger": "Heating or melting the alloy, or handling its dust",
        "consequence": "Wikipedia says the fumes are toxic and the dust may form flammable mixtures with air. Cadmium vapour from cadmium-containing alloys is a danger to humans.",
        "severity": "high",
        "source": "wikipedia-woods-metal",
        "where": "Toxicity section"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Wikipedia says contamination of bare skin is considered harmful, and that fumes are toxic.",
        "source": "wikipedia-woods-metal",
        "where": "Lead section and Toxicity section"
      },
      {
        "text": "PubChem's cadmium record lists precautionary codes P260, P264, P270 and P280 among its GHS statements. The code text is not quoted here.",
        "source": "pubchem-cadmium",
        "where": "GHS Classification section, precautionary statement codes"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "thermal-control",
      "device": "Heat-transfer medium in hot baths",
      "example": "Wikipedia says Wood's metal can be used as a heat-transfer medium in hot baths. This is a ground laboratory use.",
      "source": "wikipedia-woods-metal",
      "where": "Applications section, heat-transfer bath sentence"
    },
    {
      "application": "radiation-shielding",
      "device": "Custom-shaped apertures and blocks for medical radiation treatment",
      "example": "Wikipedia says the alloy is used for making custom-shaped apertures and blocks in medical radiation treatment. This is a ground use, not a space use.",
      "source": "wikipedia-woods-metal",
      "where": "Applications section, medical radiation sentence"
    },
    {
      "application": "mechanisms",
      "device": "Fusible link in fire-sprinkler heads, and fusible plug in boilers",
      "example": "Wikipedia says Wood's metal is used for fusible links in commercial sprinkler heads and for fusible plugs in boilers. USGS lists bismuth fusible alloys as a triggering mechanism for fire sprinklers.",
      "source": "wikipedia-woods-metal",
      "where": "Applications section, sprinkler and boiler sentences; USGS bismuth Domestic Production and Use paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Bismuth",
      "abundance": "Bismuth minerals rarely occur in quantities to be mined as principal products; it is mostly a byproduct of lead ore processing (USGS).",
      "producers": [
        {
          "country": "China",
          "share_percent": 88,
          "year": 2025
        },
        {
          "country": "Republic of Korea",
          "share_percent": 6.3,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals",
          "listed": true
        }
      ],
      "recycling": "USGS: recycled bismuth-containing alloy scrap was estimated to compose up to 10% of U.S. bismuth apparent consumption for 2021 to 2025.",
      "substitutes": [],
      "source": "usgs-mcs2026-bismuth",
      "where": "World Refinery Production table (2025 column; China 88% printed in the Events paragraph; Republic of Korea 1,000 of 16,000 t calculated by Space Mushroom); World Resources paragraph; critical list status from the USGS list page"
    },
    {
      "subject": "Cadmium",
      "abundance": "USGS: quantitative reserve estimates for cadmium were not available; the cadmium content of typical zinc ores averages about 0.03%.",
      "producers": [
        {
          "country": "China",
          "share_percent": 50,
          "year": 2024
        },
        {
          "country": "Germany",
          "share_percent": 33,
          "year": 2024
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals",
          "listed": false
        }
      ],
      "recycling": "USGS: secondary cadmium is mainly recovered from spent consumer and industrial NiCd batteries, and from copper-cadmium alloy scrap.",
      "substitutes": [
        "USGS: batteries with other chemistries, particularly lithium-ion, can replace NiCd batteries; zinc-nickel can be substituted for cadmium in many plating applications."
      ],
      "source": "usgs-mcs2026-cadmium",
      "where": "Import Sources (2021 to 2024) paragraph (China 50%, Germany 33%); Recycling; Substitutes; World Resources paragraph; critical list status from the USGS list page"
    },
    {
      "subject": "Lead",
      "producers": [
        {
          "country": "China",
          "share_percent": 42.2,
          "year": 2025
        },
        {
          "country": "Australia",
          "share_percent": 10.7,
          "year": 2025
        },
        {
          "country": "Peru",
          "share_percent": 6.4,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals",
          "listed": true
        }
      ],
      "recycling": "USGS: an estimated 1 million tons of secondary lead was produced in 2025, equivalent to 70% of apparent domestic consumption.",
      "substitutes": [
        "USGS: plastics have reduced the use of lead in cable covering and cans, and steel and zinc are common substitutes for lead in wheel weights."
      ],
      "source": "usgs-mcs2026-lead",
      "where": "World Mine Production and Reserves table (2025e, thousand metric tons lead content; world total 4,500; shares calculated by Space Mushroom from China 1,900, Australia 480 and Peru 290); Recycling; Substitutes; the 2025 list text"
    },
    {
      "subject": "Tin",
      "producers": [
        {
          "country": "China",
          "share_percent": 24.5,
          "year": 2025
        },
        {
          "country": "Indonesia",
          "share_percent": 21,
          "year": 2025
        },
        {
          "country": "Peru",
          "share_percent": 11.4,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals",
          "listed": true
        }
      ],
      "recycling": "USGS: about 17,000 tons of tin from old and new scrap was estimated to have been recycled in 2025, accounting for 22% of apparent consumption.",
      "substitutes": [],
      "source": "usgs-mcs2026-tin",
      "where": "World Mine Production table (2025e; world total 290,000 t; shares calculated by Space Mushroom from China 71,000, Indonesia 61,000 and Peru 33,000); Recycling; critical list status from the USGS list page"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Mineral Commodity Summaries 2026: Bismuth (USGS)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf",
      "year": 2026
    },
    {
      "title": "Mineral Commodity Summaries 2026: Cadmium (USGS)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cadmium.pdf",
      "year": 2026
    },
    {
      "title": "Mineral Commodity Summaries 2026: Lead (USGS)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf",
      "year": 2026
    },
    {
      "title": "Mineral Commodity Summaries 2026: Tin (USGS)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf",
      "year": 2026
    },
    {
      "title": "About the 2025 List of Critical Minerals (USGS)",
      "type": "report",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "year": 2025
    },
    {
      "title": "Wood's metal (encyclopedia article)",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Wood%27s_metal",
      "year": 2026
    },
    {
      "title": "Fusible alloy (encyclopedia article, table of well-known alloys)",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Fusible_alloy",
      "year": 2026
    },
    {
      "title": "Bismuth (encyclopedia article, physical properties and toxicity)",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Bismuth",
      "year": 2026
    },
    {
      "title": "Experimental study of the electrical conductivity, density and viscosity of a wood alloy (Kazandzhan et al., 1989, Russian)",
      "type": "paper",
      "url": "https://www.mathnet.ru/eng/tvt3860",
      "year": 1989
    },
    {
      "title": "ASM Alloy Digest, CERROBEND Alloy (abstract)",
      "type": "datasheet",
      "url": "https://dl.asminternational.org/alloy-digest/article/27/8/Bi-6/4286/CERROBEND-AlloyLow-Melting-Controlled-Shrinkage",
      "year": 1989
    },
    {
      "title": "PubChem compound record: Cadmium (CID 23973), GHS classification and density",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Cadmium",
      "year": 2026
    },
    {
      "title": "PubChem compound record: Lead (CID 5352425), GHS classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5352425",
      "year": 2026
    },
    {
      "title": "PubChem compound record: Tin (CID 5352426), GHS classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5352426",
      "year": 2026
    }
  ],
  "gaps": [
    "Thermal conductivity of Wood's metal was not found in any source read. The thermal-conductivity search returned only supplier pages that state no number.",
    "Specific heat, latent heat of fusion and thermal expansion of Wood's metal were not found in any source read.",
    "Room-temperature density of the nominal alloy was not read on a fetched page. A vendor listing gives 9.7 g/cm3 at 20 °C, but it was seen only in a search result and the vendor page could not be opened.",
    "Electrical conductivity and viscosity of the 1989 industrial alloy are given in the paper as equations and a figure, not as single values, so they are not recorded.",
    "No corrosion, oxidation or galvanic-corrosion data for Wood's metal were found, so the corrosion list is empty.",
    "No UNS, EN, ASTM or JIS designation for Wood's metal was found in any source read.",
    "Tensile strength, hardness and elongation of Wood's metal were not found beyond the two room-temperature values from Wikipedia, whose underlying test is not named.",
    "The 1989 paper's composition differs from the nominal 50/26.7/13.3/10 alloy, and its density and solidification values apply to that composition only.",
    "No space, vacuum, outgassing, UV, atomic-oxygen or radiation data for Wood's metal were found. The uses listed are ground uses.",
    "Supplier pages (VWR, Sigma-Aldrich and ThomasSci) could not be opened, so no supplier SDS or hazard statement for the alloy itself was read. The hazard data are for its constituents.",
    "Lipowitz's alloy (about 70.9 °C, Bi 49.5, Pb 27.3, Sn 13.1, Cd 10.1, from the Wikipedia fusible-alloy table) is a different composition, so it is not used as a Wood's metal value."
  ],
  "story": {
    "why": "Wood's metal is a eutectic alloy, meaning it has one fixed melting point below those of its parts. It melts at about 70 °C, which is why it is used for fusible links that must release near that temperature. Barnabas Wood invented and patented it in 1860 (Wikipedia). The alloy's weak points are its toxicity, from cadmium and lead, and the few physical data available for it.",
    "uses": [
      {
        "where": "Fire-sprinkler fusible links",
        "line": "Wikipedia says the alloy is used for fusible links in commercial sprinkler heads, where it melts in a fire to release water. USGS lists bismuth fusible alloys as a triggering mechanism for fire sprinklers."
      },
      {
        "where": "Medical radiation treatment",
        "line": "Wikipedia says the alloy is used to make custom-shaped apertures and blocks for medical radiation treatment. This is a ground use."
      },
      {
        "where": "Heat-transfer baths",
        "line": "Wikipedia says the alloy can be used as a heat-transfer medium in hot baths."
      }
    ],
    "can_do": [
      {
        "label": "Melt low",
        "line": "Wikipedia gives about 70 °C (158 °F) for the eutectic composition, and an ASM abstract gives the same figure for Cerrobend, which Wikipedia lists as identical.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "70 °C melting point"
      },
      {
        "label": "Stiffness",
        "line": "Wikipedia gives a modulus of elasticity of 12.7 GPa at room temperature. The test is not named.",
        "benchmark": "elastic_modulus",
        "scope": "material",
        "value": "12.7 GPa modulus"
      },
      {
        "label": "Strength",
        "line": "Wikipedia gives a yield strength of 26.2 MPa at room temperature. The test is not named.",
        "benchmark": "yield_strength",
        "scope": "material",
        "value": "26.2 MPa yield"
      },
      {
        "label": "Weight",
        "line": "The 1989 paper gives a density of 10.15 g/cm3 on solidification for an industrial alloy with more lead than the nominal composition.",
        "benchmark": "density",
        "scope": "material",
        "value": "10.15 g/cm3"
      }
    ],
    "compare": "The sources read for Wood's metal are few and mostly secondary. The density comes from a different composition, and no thermal value was found. The comparison rows therefore show only melting point, density and stiffness.",
    "compare_rows": [
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Stiffness",
        "benchmark": "elastic_modulus",
        "scope": "material"
      }
    ],
    "handling": [
      "Avoid skin contact. Wikipedia says contamination of bare skin is considered harmful.",
      "Do not breathe fume or dust. Wikipedia says the fumes are toxic and the dust may form flammable mixtures with air.",
      "Keep the composition in view when comparing values, because lead content varies between sources."
    ],
    "good_for": [
      "Low-melting releases near 70 °C, such as fusible links in sprinkler heads (Wikipedia).",
      "Holding fixtures and plugs where a fixed low melting point is needed (USGS lists bismuth fusible alloys for these uses)."
    ],
    "watch_out": [
      "Toxicity: cadmium (10%) and lead (26.7%) are the hazards of the alloy.",
      "Composition varies: the 1989 industrial alloy had about 40 to 41 mass % lead, against 26.7% in the nominal alloy.",
      "Few physical data: no thermal conductivity, specific heat or corrosion value was found in any source read."
    ],
    "verdict": "Wood's metal is a low-melting fusible alloy that melts at about 70 °C. It is used for sprinkler links, fusible plugs and holding fixtures. Its toxicity comes from cadmium and lead, and the physical data available are few and partly from a different composition.",
    "recipe": {
      "line": "Wood's metal is a eutectic alloy, a mixture of four metals that melts at one fixed temperature. Its nominal composition is 50% bismuth, 26.7% lead, 13.3% tin and 10% cadmium by mass (Wikipedia). The sources read do not describe how it is made.",
      "parts": [
        {
          "name": "Bismuth",
          "symbol": "Bi",
          "role": "The largest share. Wikipedia describes elemental bismuth as having unusually low toxicity for a heavy metal.",
          "share_percent": 50
        },
        {
          "name": "Lead",
          "symbol": "Pb",
          "role": "A heavy, soft component. Its share varies between sources: the 1989 paper gives 40.3 to 41.2 mass % for an industrial alloy.",
          "share_percent": 26.7
        },
        {
          "name": "Tin",
          "symbol": "Sn",
          "role": "A component of the alloy. The sources read give the share but not its individual effect on the melting point.",
          "share_percent": 13.3
        },
        {
          "name": "Cadmium",
          "symbol": "Cd",
          "role": "A component of the alloy. PubChem's aggregated notifications for cadmium carry most of the alloy's hazard codes.",
          "share_percent": 10
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The alloy contains lead and cadmium. The sources read say its fumes are toxic and that contact with bare skin is considered harmful.",
        "points": [
          {
            "label": "Cadmium and lead",
            "line": "PubChem's ECHA aggregate for cadmium reports H350 (may cause cancer) and H330 (fatal if inhaled) at 92.2% of company reports. For lead it reports H360 (may damage fertility or the unborn child) at 84.4%."
          },
          {
            "label": "Fumes and dust",
            "line": "Wikipedia says the fumes are toxic and the dust may form flammable mixtures with air. Cadmium vapour from cadmium-containing alloys is a danger to humans."
          },
          {
            "label": "Bismuth",
            "line": "Elemental bismuth has unusually low toxicity for a heavy metal (Wikipedia), so the bismuth share is not the hazard."
          }
        ]
      },
      {
        "title": "If it overheats",
        "lead": "The alloy melts near 70 °C. Above that temperature it no longer behaves as a solid.",
        "points": [
          {
            "label": "Melting",
            "line": "Wikipedia gives an approximate melting point of 70 °C (158 °F). A 1989 measurement of an industrial alloy gives a solidification temperature of 343 K (70 °C)."
          },
          {
            "label": "Strength",
            "line": "The room-temperature modulus of 12.7 GPa and yield strength of 26.2 MPa do not apply above the melting point."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Skin and fume",
            "line": "Wikipedia says contamination of bare skin is considered harmful and that the fumes are toxic. PubChem's cadmium record lists precautionary codes P260, P264, P270 and P280."
          },
          {
            "label": "Storage",
            "line": "No storage guidance for the alloy was found in any source read."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 6,
    "unreachable": 4,
    "caveats": 4,
    "note": "Read by an AI assistant on 2026-10-26. Six numeric properties are sourced: two from the Wikipedia article (melting point, room-temperature modulus and yield strength), one from the 1989 paper (solidification temperature and density, for a different composition), and one from the ASM abstract. Unreachable: VWR, Sigma-Aldrich and ThomasSci supplier pages (blocked or empty), and the MDPI review (blocked). Caveats: the Wikipedia values carry no test conditions; the 1989 alloy is not the nominal composition; the hazard data are for the constituents; no thermal or corrosion value was found."
  },
  "sources": {
    "wikipedia-woods-metal": {
      "title": "Wood's metal, Wikipedia (lead section, applications section, toxicity section)",
      "url": "https://en.wikipedia.org/wiki/Wood%27s_metal",
      "kind": "web",
      "license": "CC BY-SA 4.0, linked not reproduced"
    },
    "wikipedia-fusible-alloy": {
      "title": "Fusible alloy, Wikipedia (table of well-known alloys)",
      "url": "https://en.wikipedia.org/wiki/Fusible_alloy",
      "kind": "web",
      "license": "CC BY-SA 4.0, linked not reproduced"
    },
    "wikipedia-bismuth": {
      "title": "Bismuth, Wikipedia (infobox physical properties, lead section)",
      "url": "https://en.wikipedia.org/wiki/Bismuth",
      "kind": "web",
      "license": "CC BY-SA 4.0, linked not reproduced"
    },
    "kazandzhan1989": {
      "title": "Experimental study of the electrical conductivity, density and viscosity of a wood alloy (Kazandzhan, Matveev, Savich, Umarov; Teplofizika vysokikh temperatur 27:2, 1989, Russian)",
      "id": "Teplofizika vysokikh temperatur 27:2, pp. 269-273, paper 3860 (mathnet.ru)",
      "url": "https://www.mathnet.ru/php/getFT.phtml?jrnid=tvt&paperid=3860&what=fullt&option_lang=eng",
      "kind": "paper",
      "license": "journal page, cited not reproduced"
    },
    "asm-cerrobend": {
      "title": "ASM Alloy Digest, CERROBEND Alloy, low-melting controlled shrinkage (Bi-6)",
      "id": "ASM Alloy Digest, abstract only (full datasheet paywalled)",
      "url": "https://dl.asminternational.org/alloy-digest/article/27/8/Bi-6/4286/CERROBEND-AlloyLow-Melting-Controlled-Shrinkage",
      "kind": "datasheet",
      "license": "ASM, cited not reproduced"
    },
    "usgs-mcs2026-bismuth": {
      "title": "Mineral Commodity Summaries 2026: Bismuth (U.S. Geological Survey)",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf",
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-mcs2026-cadmium": {
      "title": "Mineral Commodity Summaries 2026: Cadmium (U.S. Geological Survey)",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cadmium.pdf",
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-mcs2026-lead": {
      "title": "Mineral Commodity Summaries 2026: Lead (U.S. Geological Survey)",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf",
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-mcs2026-tin": {
      "title": "Mineral Commodity Summaries 2026: Tin (U.S. Geological Survey)",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf",
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-crit2025": {
      "title": "About the 2025 List of Critical Minerals (U.S. Geological Survey)",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "pubchem-cadmium": {
      "title": "PubChem compound record: Cadmium (CID 23973), GHS classification and density",
      "id": "CID 23973",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Cadmium",
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "pubchem-lead": {
      "title": "PubChem compound record: Lead (CID 5352425), GHS classification",
      "id": "CID 5352425",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5352425",
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "pubchem-tin": {
      "title": "PubChem compound record: Tin (CID 5352426), GHS classification",
      "id": "CID 5352426",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5352426",
      "kind": "database",
      "license": "public domain (NCBI)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/woods-metal/"
}