{
  "spore": "profile",
  "id": "wollaston-platinum-wire",
  "spore_version": "0.2",
  "family": "precious-metals",
  "name": "Wollaston wire (silver-clad platinum and Pt-10Rh microwire)",
  "abbreviation": "Wollaston wire",
  "role": "Fine sensing wire for hot-wire anemometers and micro-thermocouples",
  "category": "metals",
  "type": "precious-metals",
  "summary": "Wollaston wire is a platinum or platinum-rhodium core drawn inside a silver sheath until the core is only a few micrometres across. Goodfellow lists core diameters of 0.0006 mm to 0.01 mm for the platinum grade and 0.0025 mm to 0.006 mm for the Pt 90/Rh 10 grade. The silver is etched away with dilute nitric acid to leave the bare core.\n",
  "best_for": "Hot-wire anemometer sensing elements and micro-thermocouple legs; Goodfellow names hot-wire anemometry as the primary application",
  "weakest_at": "Fragility of the fine core: Goodfellow says it must be handled carefully to avoid kinking or breaking, and that cutting it needs microsurgical techniques or laser ablation",
  "identity": {
    "formula": "Pt core (99.9% purity, 3N) or Pt 90/Rh 10 alloy core, both drawn in a silver sheath",
    "cas": "7440-06-4",
    "crystal_system": "face centred cubic",
    "designations": [
      {
        "system": "Trade name",
        "code": "Wollaston",
        "note": "grade name printed for the silver-sheathed fine wire; no UNS, EN or ASTM code is printed on the page",
        "source": "goodfellow-pt",
        "where": "Identification table, Grade"
      }
    ],
    "source": "goodfellow-pt",
    "where": "Identification table (Grade Wollaston, purity 99.9%, CAS 7440-06-4); Atomic Properties table (atomic number 78, atomic weight 195.08, face centred cubic)"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "thermal-control",
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density of the platinum core",
      "value": 21.45,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity, as drawn",
        "temperature": "20 °C"
      },
      "method": "Printed in the Physical Properties table of the Goodfellow page as Density (gcm⁻³) 21.45 at 20°C",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Physical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of the platinum core",
      "value": 1772,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity, as drawn"
      },
      "method": "Printed in the Thermal Properties table of the Goodfellow page as Melting point (C) 1772",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Thermal Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point of the platinum core",
      "value": 3827,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity, as drawn"
      },
      "method": "Printed in the Physical Properties table of the Goodfellow page as Boiling point (C) 3827",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Physical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity of the platinum core",
      "value": 10.58,
      "bound": "exact",
      "unit": "µOhmcm",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity, as drawn",
        "temperature": "20 °C"
      },
      "method": "Printed in the Electrical Properties table as 10.58 at 20°C; unit as printed",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Electrical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "temperature_coefficient_of_resistance",
      "label": "Temperature coefficient of resistance of the platinum core",
      "value": 0.00392,
      "bound": "exact",
      "unit": "K-1",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temperature_range": "0 to 100 °C"
      },
      "method": "Printed in the Electrical Properties table as 0.00392 at 0-100°C; not a canonical property name, see gaps",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Electrical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity of the platinum core",
      "value": 71.6,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temperature_range": "0 to 100 °C"
      },
      "method": "Printed in the Thermal Properties table as 71.6 at 0-100°C; unit as printed W m⁻¹ K⁻¹",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Thermal Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat of the platinum core",
      "value": 133,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temperature": "25 °C (printed as 025°C)"
      },
      "method": "Printed in the Thermal Properties table as 133 at 025°C; unit as printed J K⁻¹ kg⁻¹",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Thermal Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion of the platinum core",
      "value": 9,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temperature_range": "0 to 100 °C",
        "unit_in_source": "x10⁻⁶ K⁻¹ as printed"
      },
      "method": "Printed in the Thermal Properties table as 9 at 0-100 with the unit x10⁻⁶ K⁻¹; 10⁻⁶ K⁻¹ is the same as ppm/K",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Thermal Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus of the platinum core",
      "value": 170,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temper": "hard and soft (the same value is printed for both)"
      },
      "method": "Printed in the Mechanical Properties table as Tensile modulus (GPa) 170 for both columns",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Mechanical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio of the platinum core",
      "value": 0.39,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temper": "hard and soft (the same value is printed for both)"
      },
      "method": "Printed in the Mechanical Properties table as Poisson's ratio 0.39 for both columns",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Mechanical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength of the platinum core, hard temper",
      "value": 200,
      "value_high": 300,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temper": "hard"
      },
      "method": "Printed in the Mechanical Properties table as Tensile strength (MPa) 200-300 in the Hard column",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Mechanical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength of the platinum core, soft temper",
      "value": 125,
      "value_high": 150,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "temper": "soft"
      },
      "method": "Printed in the Mechanical Properties table as Tensile strength (MPa) 125-150 in the Soft column",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Mechanical Properties table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "core_diameter",
      "label": "Core diameter of the platinum wire",
      "value": 0.0006,
      "value_high": 0.01,
      "bound": "range",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "form": "silver-clad spooled wire"
      },
      "method": "Printed in the Construction and dimensions table as Core Diameter 0.0006 mm to 0.01 mm; not a canonical property name, see gaps",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Construction and dimensions table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "outside_diameter",
      "label": "Outside diameter of the silver-clad platinum wire",
      "value": 0.025,
      "value_high": 0.1,
      "bound": "range",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "grade": "Pt core, 99.9% purity",
        "form": "silver-clad spooled wire"
      },
      "method": "Printed in the Construction and dimensions table as Outside Diameter 0.025 mm to 0.1 mm; not a canonical property name, see gaps",
      "status": "ground",
      "source": "goodfellow-pt",
      "where": "Construction and dimensions table",
      "source_detail": {
        "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of the Pt 90/Rh 10 core",
      "value": 19.97,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "temperature": "not stated in the table"
      },
      "method": "Printed in the Physical Properties table of the Goodfellow Pt-Rh page as Density (gcm⁻³) 19.97",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Physical Properties table",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of the Pt 90/Rh 10 core",
      "value": 1830,
      "value_high": 1855,
      "bound": "range",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core"
      },
      "method": "Printed in the Thermal Properties table of the Goodfellow Pt-Rh page as Melting point (C) 1830-1855",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Thermal Properties table",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity of the Pt 90/Rh 10 core",
      "value": 18.4,
      "value_high": 19.2,
      "bound": "range",
      "unit": "µOhmcm",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "temperature": "not stated in the table"
      },
      "method": "Printed in the Electrical Properties table of the Goodfellow Pt-Rh page as 18.4-19.2",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Electrical Properties table",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity of the Pt 90/Rh 10 core",
      "value": 38,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "temperature": "23 °C"
      },
      "method": "Printed in the Thermal Properties table of the Goodfellow Pt-Rh page as 38 at 23°C; unit as printed W m⁻¹ K⁻¹",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Thermal Properties table",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength of the Pt 90/Rh 10 core",
      "value": 320,
      "value_high": 620,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "temper": "not named in the table (the identification table lists As Drawn)"
      },
      "method": "Printed in the Mechanical Properties table of the Goodfellow Pt-Rh page as Tensile strength (MPa) 320-620",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Mechanical Properties table",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at break of the Pt 90/Rh 10 core",
      "value": 35,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "temper": "not named in the table"
      },
      "method": "Printed in the Mechanical Properties table of the Goodfellow Pt-Rh page as Elongation at break (%) 35",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Mechanical Properties table",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "core_diameter",
      "label": "Core diameter of the Pt 90/Rh 10 wire",
      "value": 0.0025,
      "value_high": 0.006,
      "bound": "range",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "form": "silver-clad spooled wire"
      },
      "method": "Printed in the Dimensions section as Core diameter 0.0025 mm to 0.006 mm; not a canonical property name, see gaps",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Dimensions section",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "outside_diameter",
      "label": "Outside diameter of the silver-clad Pt 90/Rh 10 wire",
      "value": 0.025,
      "value_high": 0.1,
      "bound": "range",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "grade": "Pt 90/Rh 10 core",
        "form": "silver-clad spooled wire"
      },
      "method": "Printed in the Dimensions section as Outside diameter 0.025 mm to 0.1 mm; not a canonical property name, see gaps",
      "status": "ground",
      "source": "goodfellow-ptrh",
      "where": "Dimensions section",
      "source_detail": {
        "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
        "id": "Goodfellow Metals product page, accessed 2026-11-01",
        "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Air and oxygen at high temperature (bulk platinum metal)",
      "headline": "Platinum does not corrode in air, even at high temperatures.",
      "effect": "Wikipedia says platinum does not corrode, even at high temperatures, and that heated metal wires lose weight faster in air or oxygen than in a vacuum. Goodfellow says the pure platinum core resists corrosion and oxidation.",
      "rating": "none",
      "conditions": {
        "basis": "statements about platinum metal in general and Goodfellow wording for the Wollaston core; no test on the drawn wire is given in these sources"
      },
      "source": "wiki-platinum",
      "where": "Corrosion and oxidation in air section; Goodfellow Key Features (Wollaston platinum page)"
    },
    {
      "environment": "Hydrochloric and nitric acid (bulk platinum metal)",
      "headline": "Platinum is insoluble in hydrochloric and nitric acid.",
      "effect": "Wikipedia says platinum is insoluble in hydrochloric and nitric acid, and resistant to hydrochloric and sulfuric acids.",
      "rating": "none",
      "conditions": {
        "basis": "acids named alone; the same article says platinum dissolves in hot aqua regia (see next row)"
      },
      "source": "wiki-platinum",
      "where": "Acids and aqua regia section"
    },
    {
      "environment": "Hot aqua regia (bulk platinum metal)",
      "headline": "Hot aqua regia dissolves platinum.",
      "effect": "Wikipedia says platinum dissolves in hot aqua regia to form aqueous chloroplatinic acid, H2PtCl6, and gives the reaction Pt + 4 HNO3 + 6 HCl gives H2PtCl6 + 4 NO2 + 4 H2O.",
      "rating": "severe",
      "conditions": {
        "basis": "hot aqua regia, a mixture of nitric and hydrochloric acid"
      },
      "source": "wiki-platinum",
      "where": "Acids and aqua regia section"
    },
    {
      "environment": "Chlorine, bromine, iodine and sulfur (bulk platinum metal)",
      "headline": "Chlorine, bromine, iodine and sulfur attack platinum.",
      "effect": "Wikipedia says that although elemental platinum is generally unreactive, it is attacked by chlorine, bromine, iodine, and sulfur, and reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride.",
      "rating": "moderate",
      "conditions": {
        "basis": "elemental halogens and sulfur; the source gives no test on the drawn wire"
      },
      "source": "wiki-platinum",
      "where": "General chemical reactivity section"
    },
    {
      "environment": "Dilute nitric acid used to etch off the silver sheath",
      "headline": "Dilute nitric acid removes the silver sheath and leaves the platinum core.",
      "effect": "Goodfellow says the silver cladding is selectively etched away with dilute nitric acid over the active sensing length, which releases the core as a dimensionally precise, free-standing metallic element. The page reports no attack on the core itself.",
      "rating": "none",
      "conditions": {
        "exposure": "dilute nitric acid over the active sensing length, as described on the Pt-Rh page",
        "basis": "the page describes silver removal; no core corrosion is reported"
      },
      "source": "goodfellow-ptrh",
      "where": "Description section"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem's GHS record for the platinum element (CID 23939) lists H228 (flammable solid) for 10.7% of the reports, with the signal word Danger and pictogram GHS02 (flame). The record reports 410 of 504 company reports as not meeting GHS criteria. It does not state the physical form the H228 classification applies to, and it is for the element, not for drawn wire.",
        "ghs": [
          "H228"
        ],
        "source": "pubchem-pt",
        "where": "GHS Classification section, ECHA C&L Notifications Summary"
      },
      {
        "text": "The same PubChem record says 94 of 504 reports gave hazard codes: H315 (skin irritation), H319 (serious eye irritation), H334 (may cause allergy or asthma symptoms or breathing difficulties if inhaled) and H335 (may cause respiratory irritation).",
        "ghs": [
          "H315",
          "H319",
          "H334",
          "H335"
        ],
        "source": "pubchem-pt",
        "where": "GHS Classification section, GHS Hazard Statements"
      }
    ],
    "failure_risks": [
      {
        "mode": "Breakage or kinking of the ultra-fine core",
        "trigger": "Handling the spooled wire, or cutting and terminating it",
        "consequence": "Goodfellow says ultra-fine platinum wire is fragile and must be handled carefully to avoid kinking or breaking, and that cutting and termination typically need microsurgical techniques or laser ablation. The page gives no failure rate.",
        "severity": "moderate",
        "source": "goodfellow-pt",
        "where": "Handling, fragility and breakage section"
      }
    ],
    "side_effects": [
      {
        "text": "Goodfellow says the catalytic activity of platinum is retained at ultra-fine gauge, so the bare core still acts as a catalytic surface.",
        "affects": "Reactions at the wire surface",
        "source": "goodfellow-pt",
        "where": "FAQ answers"
      }
    ],
    "handling": [
      {
        "text": "Goodfellow says the silver sheath should be dissolved in dilute nitric acid rather than concentrated acid.",
        "source": "goodfellow-pt",
        "where": "Handling section"
      },
      {
        "text": "Goodfellow says connections to instrument leads are made by spot welding, ultrasonic bonding, or wrapping.",
        "source": "goodfellow-pt",
        "where": "Handling section"
      },
      {
        "text": "Goodfellow gives a wire diameter tolerance of ±10% and a length tolerance of +5% / -1%.",
        "source": "goodfellow-pt",
        "where": "Tolerances section"
      },
      {
        "text": "PubChem lists the precautionary codes P210, P240, P241, P280 and P370+P378 for the platinum element record, with the H228 flammable-solid classification.",
        "source": "pubchem-pt",
        "where": "Precautionary Statement Codes, GHS Classification section"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "thermal-control",
      "device": "Hot-wire anemometer sensing element",
      "example": "Goodfellow says hot-wire anemometry is the primary application of Wollaston platinum wire, and Wikipedia says the fastest-responding hot-wire anemometers still use it.",
      "source": "goodfellow-pt",
      "where": "Applications and uses section; FAQ answer The primary applications are hot-wire anemometry"
    },
    {
      "application": "thermal-control",
      "device": "Ultra-miniaturized Type S thermocouple junction (Pt-10Rh positive leg)",
      "example": "Goodfellow says the Pt-10%Rh wire is used to fabricate the positive leg of ultra-miniaturized Type S thermocouple junctions.",
      "source": "goodfellow-ptrh",
      "where": "Industrial Applications section"
    },
    {
      "application": "electronics-and-chips",
      "device": "Early radio electrolytic detector",
      "example": "Wikipedia says early radio detectors called electrolytic detectors used Wollaston wire.",
      "source": "wiki-wollaston",
      "where": "Applications list in the article"
    }
  ],
  "supply": [
    {
      "subject": "Platinum",
      "producers": [
        {
          "country": "South Africa",
          "share_percent": 70.6,
          "year": 2025
        },
        {
          "country": "Russia",
          "share_percent": 11.8,
          "year": 2025
        },
        {
          "country": "Zimbabwe",
          "share_percent": 10.6,
          "year": 2025
        },
        {
          "country": "Canada",
          "share_percent": 2.9,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS Final 2025 List of Critical Minerals (platinum listed in Table 6; footnote 3 says it is included in the Platinum-Group Metals chapter)",
          "listed": true
        }
      ],
      "recycling": "About 140,000 kilograms of palladium and platinum were recovered globally from new and old scrap in 2025, including about 50,000 kilograms of palladium and 8,600 kilograms of platinum recovered from automobile catalytic converters in the United States (USGS).",
      "substitutes": [
        "USGS: palladium has been used as a substitute for platinum in most gasoline-engine catalytic converters, and about 25% of palladium can routinely be substituted for platinum in diesel catalytic converters."
      ],
      "source": "usgs-mcs2026-pgm",
      "where": "Platinum-Group Metals chapter: World Mine Production and Reserves table, platinum 2025e (South Africa 120,000 kg, Russia 20,000 kg, Zimbabwe 18,000 kg, Canada 5,000 kg, world total 170,000 kg rounded; shares calculated by Space Mushroom and rounded to one decimal place); Recycling; Substitutes. Critical-list status: USGS Final 2025 List of Critical Minerals page (usgs-crit2025)"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Goodfellow Wollaston platinum wire product page (Pt 99.9%)",
      "type": "datasheet",
      "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
      "year": 2026
    },
    {
      "title": "Goodfellow Wollaston platinum-rhodium wire product page (Pt 90/Rh 10)",
      "type": "datasheet",
      "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
      "year": 2026
    },
    {
      "title": "Heraeus Precious Metals platinum datasheet (document 01, status 09/2021)",
      "type": "datasheet",
      "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Pt_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
      "year": 2021
    },
    {
      "title": "PubChem compound record for platinum (CID 23939)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/23939",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026 (Platinum-Group Metals chapter)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf",
      "year": 2026
    }
  ],
  "gaps": [
    "No flight, vacuum, radiation or space-environment result for Wollaston wire was found in the sources read; the uses are ground instruments.",
    "Vickers hardness on the Goodfellow platinum page is listed as 40 and 100 in the Hard and Soft columns, but the Key Features text gives the reverse. Not recorded.",
    "Yield strength on the Goodfellow platinum page is inconsistent: the soft yield value (185 MPa) is above the soft tensile range (125-150 MPa), and the hard yield range (14-35 MPa) is not checked. Not recorded.",
    "Brinell hardness of the Pt 90/Rh 10 core (90-165) is printed without a unit, so it is not recorded.",
    "The California Fine Wire datasheet for Platinum 10% Rhodium Wire (item 100177) is not used for values: its page blocked automated access during verification, so its figures could not be checked against the page, and no supplier-to-supplier comparison is recorded.",
    "Wikipedia gives a final platinum core of 1.5 µm (0.00006 inches) and also says the wire is about 0.001 mm thick. The two do not match and the article does not explain why; the thickness is not recorded as a property.",
    "Core diameter, outside diameter and temperature coefficient of resistance are not canonical property names; they are recorded with snake-case or descriptive names as printed.",
    "The Pt 90/Rh 10 tensile strength (320-620 MPa) is not split by temper in the Goodfellow table.",
    "The Heraeus platinum datasheet gives pure platinum values (density, melting point, thermal conductivity, Young's modulus) for bulk metal, not for this wire grade, so they are not recorded as properties.",
    "The Wikipedia bulk-platinum density and melting point (21.452 g/cm3 and 1768.3 °C in the infobox) are for bulk metal, not for this grade, so they are not recorded as properties.",
    "Rhodium supply is not covered: the USGS Platinum-Group Metals chapter gives rhodium only as imports, exports and prices, with no mine production by country, so no rhodium supplier row is recorded.",
    "Platinum crustal abundance and the EU critical raw materials status were not read for this profile.",
    "The PubChem hazard data are for the platinum element, not the drawn wire. No supplier safety data sheet for the wire was consulted.",
    "No peer-reviewed paper on Wollaston wire in hot-wire anemometers was read; the anemometer use rests on the Goodfellow page and the Wikipedia article.",
    "Sensitivity of the wire to heating in air above the platinum core's melting point is not stated in the sources read; the heating and ageing behaviour of the fine core is not recorded."
  ],
  "story": {
    "why": "Wollaston wire is a fine core of platinum or Pt 90/Rh 10 alloy drawn inside a silver sheath. Goodfellow says the process extends the diameter range of platinum wire downward to sub-micrometre diameters, for specialized research applications. The platinum grade has a core diameter of 0.0006 mm to 0.01 mm, and the Pt 90/Rh 10 grade 0.0025 mm to 0.006 mm, with an outside diameter of 0.025 mm to 0.1 mm for both. The silver sheath is removed after drawing, so the bare core is what sensing elements use. Heraeus lists platinum wire among its platinum product forms.",
    "uses": [
      {
        "where": "Hot-wire anemometers",
        "line": "Goodfellow calls hot-wire anemometry the primary application of Wollaston platinum wire. Wikipedia says the fastest-responding hot-wire anemometers still use it."
      },
      {
        "where": "Micro-thermocouples",
        "line": "Goodfellow says the platinum grade is used for the negative leg of ultra-miniaturized Type R and Type S thermocouple junctions, and the Pt 90/Rh 10 grade for the positive leg of ultra-miniaturized Type S junctions."
      },
      {
        "where": "Early radio detectors",
        "line": "Wikipedia says early radio detectors called electrolytic detectors used Wollaston wire, and that it was also used in the hot-wire barretter."
      }
    ],
    "can_do": [
      {
        "label": "Sense gas flow",
        "line": "Goodfellow names hot-wire anemometry as its primary application.",
        "scope": "material"
      },
      {
        "label": "Measure temperature",
        "line": "Measure temperature in micro-thermocouples, where the platinum grade forms the negative leg of Type R and Type S junctions.",
        "scope": "material"
      },
      {
        "label": "Heat and sense",
        "line": "Act as a heater and a thermometer at once, since the wire can heat itself by Joule heating and read its own resistance, as Goodfellow says.",
        "scope": "material"
      }
    ],
    "compare": "The platinum core has a higher density (21.45 g/cm3) and a lower melting point (1772 °C) than the Pt 90/Rh 10 core (19.97 g/cm3 and 1830 to 1855 °C per Goodfellow). Its electrical resistivity is lower, at 10.58 µOhmcm at 20 °C against 18.4 to 19.2 µOhmcm for the alloy. Both grades are sold as silver-clad spooled wire, and the table compares their key values.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Electrical resistivity",
        "benchmark": "electrical_resistivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Keep the wire spooled and handle it with care: Goodfellow says it is fragile and can kink or break.",
      "Etch the silver sheath with dilute nitric acid, not concentrated acid (Goodfellow).",
      "Join leads by spot welding, ultrasonic bonding or wrapping (Goodfellow).",
      "Keep fine platinum away from heat and ignition sources, since PubChem gives the element the flammable-solid class H228 with precautionary codes P210 and P240."
    ],
    "good_for": [
      "Hot-wire anemometry, where Goodfellow names it as the primary application.",
      "Micro-thermocouples, with the platinum grade as the negative leg of Type R and Type S junctions (Goodfellow)."
    ],
    "watch_out": [
      "Fragility of the fine core, which Goodfellow says can kink or break.",
      "Goodfellow gives the Pt 90/Rh 10 density and electrical resistivity without a stated temperature, so compare them only with that caveat.",
      "The silver sheath gives mechanical support during drawing and is etched away for most uses (Wikipedia)."
    ],
    "verdict": "Wollaston wire is the fine-core choice for hot-wire anemometry and micro-thermocouples, provided the fragile core is handled with care.",
    "recipe": {
      "line": "Wollaston wire is a platinum or Pt 90/Rh 10 core drawn inside a silver sheath. Goodfellow says the silver sheath gives the mechanical support needed to draw the core to fine diameters, and the sheath is etched away with dilute nitric acid over the active sensing length.",
      "parts": [
        {
          "name": "Platinum",
          "symbol": "Pt",
          "role": "The core metal of the platinum grade (99.9% purity). Platinum has atomic number 78 and is a noble metal.",
          "atoms": 1,
          "atomic_weight": 195.08
        },
        {
          "name": "Rhodium",
          "symbol": "Rh",
          "role": "The alloying metal of the Pt 90/Rh 10 grade, at 10 per cent of the core by weight."
        },
        {
          "name": "Silver",
          "symbol": "Ag",
          "role": "The sheath that carries the core through drawing and is etched off with dilute nitric acid."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The platinum element is not classed as hazardous in most PubChem reports, but a minority of reports give flammability and respiratory codes.",
        "points": [
          {
            "label": "The metal",
            "line": "PubChem reports that 410 of 504 company reports do not meet GHS criteria for the platinum element."
          },
          {
            "label": "Flammable class",
            "line": "PubChem lists H228 (flammable solid) for 10.7% of the reports, with the signal word Danger. The record does not say which physical form it applies to."
          },
          {
            "label": "Respiratory and skin codes",
            "line": "From 94 of 504 reports that gave codes, PubChem lists H315, H319, H334 and H335, which cover skin and eye irritation and sensitisation by inhalation."
          }
        ],
        "level": 0,
        "verdict": "Pure platinum is inert; the fine wire is fragile"
      },
      {
        "title": "Handling the wire",
        "lead": "The main risk in handling Wollaston wire is mechanical, not toxic.",
        "points": [
          {
            "label": "Fragility",
            "line": "Goodfellow says ultra-fine platinum wire is fragile and must be handled carefully to avoid kinking or breaking."
          },
          {
            "label": "Acid etching",
            "line": "Goodfellow says the silver sheath should be dissolved in dilute nitric acid rather than concentrated acid."
          },
          {
            "label": "Joining",
            "line": "Goodfellow says leads are joined by spot welding, ultrasonic bonding, or wrapping."
          }
        ],
        "level": 1
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 22,
    "unreachable": 1,
    "caveats": 4,
    "note": "Values read by an AI assistant on 2026-11-01 from the Goodfellow product pages, the Wikipedia articles, PubChem, the USGS Mineral Commodity Summaries 2026 and the Heraeus platinum datasheet. The California Fine Wire datasheet was read but its values are not recorded, because its page blocks automated access."
  },
  "sources": {
    "goodfellow-pt": {
      "title": "Pure Wollaston Platinum Wire, Pt 99.9% (3N), spooled wire product page",
      "id": "Goodfellow Metals product page, accessed 2026-11-01",
      "url": "https://www.goodfellow.com/usa/wollaston-platinum-spooled-wire-group",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier product page, cited not reproduced"
    },
    "goodfellow-ptrh": {
      "title": "Wollaston Platinum-Rhodium Spooled Wire, Pt 90/Rh 10, product page",
      "id": "Goodfellow Metals product page, accessed 2026-11-01",
      "url": "https://www.goodfellow.com/usa/wollaston-platinum-rhodium-alloy-spooled-wire-pt90-rh10-group",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier product page, cited not reproduced"
    },
    "heraeus-pt": {
      "title": "Platinum datasheet, Heraeus Precious Metals (document 01, status 09/2021)",
      "id": "Heraeus Precious Metals datasheet, document 01",
      "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Pt_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
      "year": 2021,
      "kind": "datasheet",
      "license": "supplier datasheet, cited not reproduced"
    },
    "wiki-wollaston": {
      "title": "Wollaston wire, Wikipedia article",
      "id": "Wikipedia, accessed 2026-11-01",
      "url": "https://en.wikipedia.org/wiki/Wollaston_wire",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0"
    },
    "wiki-platinum": {
      "title": "Platinum, Wikipedia article (corrosion, acids and reactivity sections)",
      "id": "Wikipedia, accessed 2026-11-01",
      "url": "https://en.wikipedia.org/wiki/Platinum",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0"
    },
    "pubchem-pt": {
      "title": "PubChem compound record, Platinum (CID 23939), GHS classification and CAS number",
      "id": "CID 23939; CAS 7440-06-4",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23939/JSON",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI); classifications attributed to ECHA notifiers"
    },
    "usgs-mcs2026-pgm": {
      "title": "Mineral Commodity Summaries 2026, Platinum-Group Metals chapter",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-crit2025": {
      "title": "About the 2025 List of Critical Minerals (USGS)",
      "id": "Final 2025 List of Critical Minerals",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "year": 2025,
      "kind": "web",
      "license": "public domain (USGS)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/wollaston-platinum-wire/"
}