Galinstan GaInSn

spore: profile
id: galinstan
spore_version: 0.2
family: low-melting-metals-and-solders
name: Galinstan
abbreviation: GaInSn
role: liquid-metal conductor and heat-transfer fluid
category: metals
type: heavy-metals
summary: |
  Galinstan is a gallium-indium-tin alloy that is liquid at room temperature. Its printed composition is 68.5 % Ga, 21.5 % In and 10 % Sn by mass. The Rotometals safety data sheet prints a melting point of -19 C and a boiling point of 1300 C. A 2026 measurement at about 21 C gives a density of 6.488 g/cm3 and an electrical conductivity of 3.46 MS/m. A 2021 review gives a thermal conductivity of 25.4 W/m.K for the same alloy. In air the alloy forms a thin Ga2O3 oxide skin, which the same review gives as 0.5 to 3 nm. The skin can plug narrow capillaries, and the sources give no rate of corrosion for aluminium.
best_for: Liquid-metal heat transfer and conduction at or above -19 C, such as a liquid-metal microchannel heat sink or a stretchable conductor, where the alloy has to stay liquid and metallic
weakest_at: 'Oxide film and aluminium: the oxide skin plugs narrow passages, and the introduction of one source reports corrosivity to aluminium with no rate or test'
identity:
  formula: 'Ga 68.5 %, In 21.5 %, Sn 10 % by mass: near-eutectic gallium-indium-tin liquid-metal alloy'
  source: sds-rotometals
  where: 'Section 1 (Product Name Galinstan) and Section 3 (Composition table: Gallium 68.5, Indium 21.5, Tin 10 weight %)'
  designations:
    - system: Trade name
      code: Galinstan
      source: sds-rotometals
      where: Section 1, Product Name line
tags:
  applications:
    - thermal-control
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density of galinstan (Rotometals SDS)
    value: 6.44
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      composition: Ga 68.5 %, In 21.5 %, Sn 10 % by mass
    method: Value printed in the Relative Density line of the safety data sheet, which cites a reference in brackets that was not opened
    status: ground
    source: sds-rotometals
    where: Section 9, Relative Density line (6.44 g/cm3 at 20 C)
  - benchmark: density
    label: Density of galinstan, measured near room temperature (KJMM 2026)
    value: 6.488
    unit: g/cm3
    scope: material
    conditions:
      temperature: about 21 °C
      uncertainty: +/- 0.265 g/cm3, as printed
      composition: Ga68.5 In21.5 Sn10 (wt %)
    method: Measured by the authors and printed in the measured properties of the article
    status: ground
    source: kjmm-2026
    where: Measured properties table, density row
  - benchmark: kinematic_viscosity
    label: Kinematic viscosity of galinstan, acid-covered sample (KJMM 2026)
    value: 0.474
    unit: cSt
    scope: material
    conditions:
      temperature: about 21 °C
      uncertainty: 0.018 cSt bound, as printed
      composition: Ga68.5 In21.5 Sn10 (wt %)
      treatment: sample covered with sulfuric acid at pH 0
    method: Ubbelohde size 0 viscometer calibrated with the N.4 standard; the authors say the value is above a literature value of 0.329 cSt and attribute the gap to partial capillary obstruction by untreated oxides
    status: ground
    source: kjmm-2026
    where: Table 1, acid-covered kinematic viscosity row
  - benchmark: electrical_conductivity
    label: Electrical conductivity of galinstan (review table)
    value: 3.4
    unit: MS/m
    scope: material
    conditions:
      composition: 68.5 % Ga, 21.5 % In, 10 % Sn
      temperature: not stated
      unit_in_source: 3.40 * 10^6 S/m
    method: Printed as 3.40 * 10^6 S/m in the Galinstan row; converted to megasiemens per metre (1 MS/m = 10^6 S/m) without changing the digits
    status: ground
    source: alizadeh-2021
    where: Table 1, Galinstan row
    note: The KJMM measurement at about 21 C (next row) is 3.46 MS/m, so the two sources differ by about 1.8 %
  - benchmark: electrical_conductivity
    label: Electrical conductivity of galinstan, measured (KJMM 2026)
    value: 3.46
    unit: MS/m
    scope: material
    conditions:
      temperature: about 21 °C
      uncertainty: 0.09 MS/m, as printed
      composition: Ga68.5 In21.5 Sn10 (wt %)
      unit_in_source: 3.46*10^6 +/- 0.09*10^6 S/m
    method: In-house four-point probe calibrated with Wood's metal. The fetched text lost its superscript; the value is converted to MS/m from 3.46*10^6 +/- 0.09*10^6 S/m without changing the digits.
    status: ground
    source: kjmm-2026
    where: Measured properties table, electrical conductivity row
  - benchmark: thermal_conductivity
    label: Thermal conductivity of galinstan (review table)
    value: 25.4
    unit: W/m.K
    scope: material
    conditions:
      composition: 68.5 % Ga, 21.5 % In, 10 % Sn
      temperature: not stated
    method: Printed in the Galinstan row of Table 1 as W/m.K
    status: ground
    source: alizadeh-2021
    where: Table 1, Galinstan row
    note: The Wikipedia article prints a lower value of 16.5 W/m.K. It is a secondary source and is not entered here.
  - benchmark: melting_point
    label: Melting point of galinstan (review table)
    value: -19
    unit: °C
    scope: material
    conditions:
      composition: 68.5 % Ga, 21.5 % In, 10 % Sn
    method: Printed as -19 C in the Galinstan row of Table 1
    status: ground
    source: alizadeh-2021
    where: Table 1, Galinstan row, melting temperature column
  - benchmark: melting_point
    label: Melting point of galinstan (Rotometals SDS)
    value: -19
    unit: °C
    scope: material
    conditions:
      composition: Ga 68.5 %, In 21.5 %, Sn 10 % by mass
    method: Printed in the Melting Point/Range line of the safety data sheet
    status: ground
    source: sds-rotometals
    where: Section 9, Melting Point/Range line (-19 °C)
  - benchmark: boiling_point
    label: Boiling point of galinstan (Rotometals SDS)
    value: 1300
    unit: °C
    scope: material
    conditions:
      pressure: not stated
    method: Printed in the Boiling Point/Range line of the safety data sheet as 1300°C
    status: ground
    source: sds-rotometals
    where: Section 9, Boiling Point/Range line
    note: The Wikipedia article prints "> 1300 °C", a lower bound that is not entered
  - benchmark: melting_point
    label: Melting point of eutectic gallium-indium, EGaIn (review table)
    value: 15.5
    unit: °C
    scope: material
    conditions:
      composition: 75.5 % Ga, 24.5 % In (eutectic)
    method: Printed in the Eutectic Gallium-Indium row of Table 1
    status: ground
    source: alizadeh-2021
    where: Table 1, Eutectic Gallium-Indium row, melting temperature column
  - benchmark: electrical_conductivity
    label: Electrical conductivity of eutectic gallium-indium, EGaIn (review table)
    value: 3.46
    unit: MS/m
    scope: material
    conditions:
      composition: 75.5 % Ga, 24.5 % In (eutectic)
      temperature: not stated
      unit_in_source: 3.46 * 10^6 S/m
    method: Printed as 3.46 * 10^6 S/m in the EGaIn row; converted to megasiemens per metre without changing the digits
    status: ground
    source: alizadeh-2021
    where: Table 1, Eutectic Gallium-Indium row
  - benchmark: thermal_conductivity
    label: Thermal conductivity of eutectic gallium-indium, EGaIn (review table)
    value: 26.4
    unit: W/m.K
    scope: material
    conditions:
      composition: 75.5 % Ga, 24.5 % In (eutectic)
      temperature: not stated
    method: Printed in the EGaIn row of Table 1 as W/m.K
    status: ground
    source: alizadeh-2021
    where: Table 1, Eutectic Gallium-Indium row
corrosion:
  - environment: Air or oxygen at room temperature
    headline: A thin self-passivating Ga2O3 oxide skin forms in air, about 0.5 to 3 nm thick.
    effect: The review says the skin lowers the surface tension of droplets, acts as an elastic membrane, and increases adhesion to the substrate. The KJMM paper says the alloy has a known tendency to form an oxide film, and it reports that a sample left in air formed an oxide layer on the surface but did not seem to heavily oxidize.
    rating: low
    conditions:
      basis: the 0.5 to 3 nm range is a literature range the review quotes for Ga-based liquid metals, not a measured rate for galinstan
    source: alizadeh-2021
    where: Oxide layer paragraph, Ga-based liquid metals (section on EGaIn and Ga-In-Sn)
  - environment: Aluminium surfaces
    headline: The source reports corrosivity towards aluminium, with no rate or test.
    effect: The KJMM introduction says the alloy is reported to have corrosivity towards metals and particularly aluminium and its alloys. The article does not give a rate, a test duration or the specimen condition for that statement, and the galinstan safety data sheet does not list aluminium.
    rating: unknown
    conditions:
      basis: literature statement quoted in the introduction, not tested in the article
    source: kjmm-2026
    where: Section 1 (Introduction)
  - environment: Contact with strong bases, other metals and moisture
    headline: The SDS lists strong bases, metals and alkali metals as incompatible, and says the product is hygroscopic.
    effect: The safety data sheet names strong bases, metals, alkali metals and powdered metals as incompatible materials, and gives exposure to moisture as a condition to avoid. It gives no corrosion rate.
    rating: unknown
    conditions:
      basis: compatibility list in the safety data sheet, not a corrosion test
    source: sds-rotometals
    where: Section 10, Incompatible Materials and Conditions to Avoid lines
risks:
  hazards:
    - text: The Rotometals SDS (2015) lists the signal word Warning and the hazard statements harmful if swallowed, causes skin irritation and causes serious eye irritation. It gives the statements in words, with no H codes printed.
      ghs: []
      source: sds-rotometals
      where: Section 2, Hazard Statements and Signal Word lines
  failure_risks:
    - mode: Oxide skin plugs a narrow capillary
      trigger: Flow through a narrow capillary, such as a viscometer tube, with oxide present on the alloy
      consequence: The KJMM authors say the viscometer capillary plugged easily when they tested the Ga-In-Sn alloy, and they believed oxide formation was the cause. The article gives no plug time or flow rate at which plugging occurs.
      severity: moderate
      source: kjmm-2026
      where: Section 2.3 (viscometer capillary plugging)
    - mode: Oxide skin breaks under high surface stress
      trigger: Surface stress above a critical value of 0.5 to 0.6 N/m, stated for Ga-based liquid metals
      consequence: The skin breaks and reforms immediately, so droplets change shape and then hold it again. The review treats this as a feature for printing and moulding, so the severity is low.
      severity: low
      source: alizadeh-2021
      where: Oxide layer paragraph, Ga-based liquid metals
  side_effects: []
  handling:
    - text: Store under an inert atmosphere, in tightly closed containers in a dry, cool, well-ventilated place (SDS Section 7).
      source: sds-rotometals
      where: Section 7, Storage line
    - text: Keep away from strong bases, metals, alkali metals and powdered metals, and avoid exposure to moisture (SDS Section 10).
      source: sds-rotometals
      where: Section 10, Incompatible Materials and Conditions to Avoid lines
    - text: Wear eye and skin protection and use good industrial hygiene. Rinse eyes or skin with water for at least 15 minutes after contact (SDS Sections 4 and 8).
      source: sds-rotometals
      where: Sections 4 and 8
  mitigations:
    - text: Treatment with sulfuric acid at pH 0 alleviated the oxidation in the KJMM tests and restored flowability, but the acid was not entirely effective within the bulk fluid volume.
      source: kjmm-2026
      where: Abstract and Section 4 (Conclusions)
uses:
  - application: thermal-control
    device: Liquid-metal microchannel heat sink
    example: A 2026 numerical study models a galinstan-cooled mini-channel heat sink for a high-heat-flux microelectronic chip. It is a simulation, not a built device, and its property table uses Ga68In20Sn12 rather than the galinstan composition.
    source: micromachines-2026
    where: Abstract and Section 2.1 (high-heat-flux chip in contact with the substrate)
  - application: electronics-and-chips
    device: Liquid-metal-embedded elastomers for stretchable electronics
    example: The review names Ga-In-Sn (Galinstan) and eutectic Ga-In as popular liquid-metal alloys for liquid-metal-embedded elastomers used in stretchable electronics and wearable devices.
    source: alizadeh-2021
    where: Section on liquid-metal-embedded elastomers, paragraph naming Ga-In-Sn (Galinstan)
supply:
  - subject: Gallium, primary low-purity production
    producers:
      - country: China
        share_percent: 99
        year: 2025
    critical_lists: []
    abundance: 'USGS: the average gallium content of bauxite is 50 parts per million, and gallium in world bauxite resources is estimated to exceed 1 million tons.'
    recycling: 'USGS: old scrap, none. Substantial new scrap from GaAs device manufacture was reprocessed to high-purity gallium at one facility in New York.'
    substitutes:
      - 'USGS: silicon is the principal competitor with GaAs in solar-cell applications, and silicon-germanium replaces GaAs in some heterojunction bipolar transistors.'
    source: usgs-mcs2026-gallium
    where: Events, Trends, and Issues paragraph (China 99 %, year as printed for 2025); World Resources; Recycling line; Substitutes paragraph
  - subject: Gallium metal imports to the United States
    producers:
      - country: Canada
        share_percent: 28
        year: 2024
      - country: Japan
        share_percent: 22
        year: 2024
      - country: China
        share_percent: 18
        year: 2024
      - country: Germany
        share_percent: 16
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-gallium
    where: Import Sources (2021-24) line, metal shares; the year is the end of the 2021 to 2024 period as printed
  - subject: Indium, world refinery production
    producers:
      - country: China
        share_percent: 70
        year: 2025
    critical_lists: []
    recycling: 'USGS: indium is most commonly recovered from ITO scrap in Japan and the Republic of Korea. Data on the quantity recovered were not available.'
    substitutes:
      - 'USGS: antimony tin oxide, carbon nanotube coatings, PEDOT and copper or silver nanowires have been developed as alternatives to ITO coatings.'
    source: usgs-mcs2026-indium
    where: Events, Trends, and Issues paragraph (China 70 % of world total); Recycling line; Substitutes paragraph
  - subject: Indium imports to the United States
    producers:
      - country: Republic of Korea
        share_percent: 25
        year: 2024
      - country: Japan
        share_percent: 22
        year: 2024
      - country: China
        share_percent: 12
        year: 2024
      - country: Canada
        share_percent: 11
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-indium
    where: Import Sources (2021-24) line; the year is the end of the 2021 to 2024 period as printed
  - subject: Tin, refined imports to the United States
    producers:
      - country: Peru
        share_percent: 31
        year: 2024
      - country: Bolivia
        share_percent: 27
        year: 2024
      - country: Indonesia
        share_percent: 15
        year: 2024
      - country: Brazil
        share_percent: 10
        year: 2024
    critical_lists: []
    recycling: 'USGS: about 17,000 tons of tin from old and new scrap was recycled in 2025, which the summary gives as 22 % of apparent consumption.'
    source: usgs-mcs2026-tin
    where: Import Sources (2021-24) line; Recycling paragraph
documents:
  - title: Rotometals galinstan safety data sheet, version 1.7, revised 2015-05-15
    type: sds
    url: https://fu.sav.sk/wp-content/uploads/uploaded/documents/BOZP/chem_bezp/MSDS/galinstan_rotometals.pdf
    year: 2015
  - title: Gallium-Indium-Tin Alloy Properties and Treatment with Sulfuric Acid, Korean Journal of Metals and Materials 64(4)
    type: paper
    url: https://doi.org/10.3365/KJMM.2026.64.4.312
    year: 2026
  - title: 'Robust and Multifunctional Liquid-Metal Embedded Elastomers for Ultrastretchable Electronics: a Short Review (arXiv 2104.07327)'
    type: paper
    url: https://arxiv.org/pdf/2104.07327
    year: 2021
  - title: Numerical Study on Heat Transfer Performance of Turbulence Enhancement Configurations for Galinstan Based Mini-Channel Cooling, Micromachines 17(1):83
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC12843614/
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Gallium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Indium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Tin'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements, gallium
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Ga&all=all&ascii=html
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements, indium
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=In&all=all&ascii=html
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements, tin
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Sn&all=all&ascii=html
  - title: 'Wikipedia: Galinstan (composition and history only)'
    type: database
    url: https://en.wikipedia.org/wiki/Galinstan
gaps:
  - Specific heat of galinstan was not found in a primary source. The Wikipedia article prints 296 J/kg.K, which is a secondary source and is not entered.
  - Surface tension was not entered. The review's Table 1 prints 534 for galinstan with no unit, and the Wikipedia article gives a producer-dependent range (0.535 to 0.718 N/m), which is secondary.
  - Coefficient of thermal expansion was not found in any fetched source.
  - 'Vapour pressure: the SDS prints 10^-8 Torr at 500 C as a bound, which is not a value, so it was left out.'
  - 'Thermal conductivity conflicts: the review prints 25.4 W/m.K and the Wikipedia article prints 16.5 W/m.K. The KJMM paper did not report thermal conductivity, and the Micromachines paper gives only a temperature formula for Ga68In20Sn12.'
  - 'Non-canonical property names used as they are: electrical_conductivity and kinematic_viscosity are not in spores/property-canon.yaml.'
  - Dynamic viscosity of 3.076 x 10^-3 kg/m s (uncertainty 0.173 x 10^-3 kg/m s) is printed in KJMM Table 1 but was not entered, because the printed exponent cannot be written as a plain value without changing the printed unit.
  - 'Eutectic gallium-indium melting point 15.7 C from a vendor listing was not used: the VWR page returned HTTP 403 and only a search snippet was available.'
  - 'The Geratherm galinstan SDS was not downloaded: the University of Minnesota copy returned no file. A search snippet describing a 2006 Geratherm sheet as corrosive is not used.'
  - Hazard codes for pure gallium metal (H290 in an Avantor sheet) were not fetched. The PubChem record for gallium returned a browser check, so no PubChem GHS data were read.
  - The commercial product may contain added flux (Wikipedia). No primary source was read for the flux, so the composition is the SDS composition only.
  - Critical-mineral status of gallium, indium and tin was not found in the fetched USGS text, so critical_lists is empty.
  - Gallium and indium supply shares are from the USGS text. The China gallium share of 99 % is given without a year in the paragraph, so the year 2025 is taken from the report's period.
  - No outgassing, atomic oxygen, radiation or UV data for galinstan in space were searched in this run.
  - 'No media: no image licence was checked.'
sources:
  sds-rotometals:
    title: 'Rotometals, Inc. Safety Data Sheet: Galinstan, version 1.7 (revision date 2015-05-15)'
    id: Rotometals galinstan SDS v1.7
    url: https://fu.sav.sk/wp-content/uploads/uploaded/documents/BOZP/chem_bezp/MSDS/galinstan_rotometals.pdf
    year: 2015
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  kjmm-2026:
    title: Gallium-Indium-Tin Alloy Properties and Treatment with Sulfuric Acid, Korean Journal of Metals and Materials 64(4), pp. 312-324 (Raadam and Lee)
    id: DOI 10.3365/KJMM.2026.64.4.312
    url: https://kjmm.org/kjmm/XmlViewer/f451272
    year: 2026
    kind: paper
    license: cited, not reproduced
  alizadeh-2021:
    title: 'Robust and Multifunctional Liquid-Metal Embedded Elastomers for Ultrastretchable Electronics: a Short Review (Kaveh Alizadeh)'
    id: arXiv 2104.07327
    url: https://arxiv.org/pdf/2104.07327
    year: 2021
    kind: paper
    license: arXiv preprint, cited not reproduced
  micromachines-2026:
    title: Numerical Study on Heat Transfer Performance of Turbulence Enhancement Configurations for Galinstan Based Mini-Channel Cooling (Li, Han, Wang, Dai, Chen), Micromachines 17(1):83
    id: DOI 10.3390/mi17010083
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC12843614/
    year: 2026
    kind: paper
    license: cited, not reproduced
  usgs-mcs2026-gallium:
    title: 'Mineral Commodity Summaries 2026: Gallium (U.S. Geological Survey)'
    id: USGS MCS 2026, prepared by Emily K. Schnebele
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-indium:
    title: 'Mineral Commodity Summaries 2026: Indium (U.S. Geological Survey)'
    id: USGS MCS 2026, prepared by Rob Crangle
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-tin:
    title: 'Mineral Commodity Summaries 2026: Tin (U.S. Geological Survey)'
    id: USGS MCS 2026, prepared by Chad A. Friedline
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  nist-ga:
    title: NIST Atomic Weights and Isotopic Compositions for All Elements, gallium (Ga, Z = 31)
    id: standard atomic weight 69.723(1)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Ga&all=all&ascii=html
    kind: database
    license: US government data
  nist-in:
    title: NIST Atomic Weights and Isotopic Compositions for All Elements, indium (In, Z = 49)
    id: standard atomic weight 114.818(1)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=In&all=all&ascii=html
    kind: database
    license: US government data
  nist-sn:
    title: NIST Atomic Weights and Isotopic Compositions for All Elements, tin (Sn, Z = 50)
    id: standard atomic weight 118.710(7)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Sn&all=all&ascii=html
    kind: database
    license: US government data
  wikipedia-galinstan:
    title: Galinstan, Wikipedia (used for composition and history only)
    url: https://en.wikipedia.org/wiki/Galinstan
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 12
  unreachable: 3
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry (USGS and SDS text extracted from PDFs with pdftotext; KJMM values from the article''s XML viewer; arXiv values from Table 1 of the PDF). Unreachable: VWR catalog (HTTP 403), PubChem gallium record (browser check), University of Minnesota SDS (no file). Caveats: galinstan thermal conductivity differs between the review (25.4 W/m.K) and Wikipedia (16.5 W/m.K); the KJMM composition is Ga68.5In21.5Sn10 and the review''s is the same; surface tension has no printed unit in the review; the Micromachines property table uses Ga68In20Sn12 and is not used for values.'
story:
  recipe:
    line: Galinstan is a near-eutectic blend of gallium, indium and tin, by mass 68.5 % Ga, 21.5 % In and 10 % Sn (Rotometals SDS, Section 3). Wikipedia calls it near-eutectic rather than eutectic and says the commercial product may contain added flux, which no primary source read here confirms. The sources read give no process route.
    parts:
      - name: Gallium
        symbol: Ga
        share_percent: 68.5
        role: Largest component by mass (SDS Section 3). The review says the oxide skin that forms in air is Ga2O3.
      - name: Indium
        symbol: In
        share_percent: 21.5
        role: Second component by mass (SDS Section 3).
      - name: Tin
        symbol: Sn
        share_percent: 10
        role: Smallest component by mass (SDS Section 3).
  risk_groups:
    - title: For people
      lead: The SDS lists skin and eye irritation and harm if swallowed, with no toxicity data beyond that.
      level: 1
      verdict: Irritant, low acute toxicity
      points:
        - label: Hazard statements
          line: The Rotometals SDS gives the signal word Warning and the statements harmful if swallowed, causes skin irritation and causes serious eye irritation.
        - label: Exposure
          line: The SDS gives no exposure limit for gallium, indium or tin, and says inhalation does not pose any risk.
    - title: If it fails
      lead: The failure routes in these sources are an oxide skin that plugs narrow passages and a skin that breaks under high surface stress.
      verdict: Oxide plugging, not toxicity
      points:
        - label: Capillary plugging
          line: In the KJMM tests the viscometer capillary plugged easily with the Ga-In-Sn alloy, which the authors attribute to oxide formation.
        - label: Surface stress
          line: The review gives a critical surface stress of 0.5 to 0.6 N/m for the oxide skin of Ga-based liquid metals, above which the skin breaks and reforms.
    - title: Handling and storage
      verdict: Inert, dry storage
      points:
        - label: Atmosphere
          line: The SDS says to store under an inert atmosphere in tightly closed containers, and to keep the alloy away from moisture.
        - label: Incompatible materials
          line: The SDS names strong bases, metals, alkali metals and powdered metals as incompatible.
  why: Galinstan is a gallium-indium-tin alloy that is liquid at room temperature, with a printed melting point of -19 C and a printed boiling point of 1300 C. The review and the 2026 measurement agree on a conductivity of about 3.4 to 3.46 MS/m, and the review gives a thermal conductivity of 25.4 W/m.K. It was developed as a mercury substitute (KJMM introduction) and is now studied for liquid-metal heat sinks and stretchable electronics.
  uses:
    - where: Liquid-metal microchannel heat sink
      line: A 2026 simulation studies a galinstan-cooled mini-channel heat sink for a high-heat-flux chip (Micromachines).
    - where: Stretchable electronics
      line: The review names galinstan and eutectic Ga-In as popular liquid-metal alloys for liquid-metal-embedded elastomers.
  can_do:
    - label: Stay liquid
      value: '-19 °C melting point'
      benchmark: melting_point
      line: Galinstan melts at -19 C (review Table 1 and the Rotometals SDS).
    - label: Carry heat
      value: 25.4 W/m.K
      benchmark: thermal_conductivity
      line: The review gives 25.4 W/m.K (Table 1). The Wikipedia value of 16.5 W/m.K is lower and is not used here.
    - label: Carry current
      value: 3.46 MS/m
      benchmark: electrical_conductivity
      line: The KJMM measurement at about 21 C is 3.46 MS/m, with an uncertainty of 0.09 MS/m.
    - label: Weight
      value: 6.488 g/cm3
      benchmark: density
      line: The KJMM measurement at about 21 C is 6.488 g/cm3, with an uncertainty of 0.265 g/cm3. The SDS gives 6.44 g/cm3 at 20 C.
  compare: The sources read for galinstan are for slightly different compositions and conditions, and the EGaIn row (eutectic gallium-indium) is a different alloy, so read the table rows as examples, not a ranking.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Store under an inert atmosphere in tightly closed containers, in a dry, cool, well-ventilated place (SDS).
    - Keep away from strong bases, metals and alkali metals, and avoid moisture (SDS).
    - The KJMM tests cleaned the oxide with sulfuric acid at pH 0 and restored flowability, which is the cleaning route the sources describe.
  good_for:
    - Liquid-metal heat transfer and conduction above -19 C, with a thermal conductivity of 25.4 W/m.K (review).
    - Stretchable conductors, where the oxide skin helps the droplets keep their shape and stick to the elastomer (review).
  watch_out:
    - 'Oxide skin: it forms in air at 0.5 to 3 nm and can plug narrow capillaries (review, KJMM).'
    - 'Aluminium: the KJMM introduction reports corrosivity towards aluminium, with no rate or test.'
    - 'Composition: the SDS composition is near-eutectic, and the sources do not agree on the thermal conductivity (25.4 vs 16.5 W/m.K).'
  verdict: Galinstan is a room-temperature liquid metal with a melting point of -19 C and a thermal conductivity of 25.4 W/m.K in the review. Its irritant hazard is low according to the SDS. The sources' weak points are the oxide skin, which can plug narrow passages, and a reported but unmeasured corrosivity towards aluminium. The profile lacks specific heat, thermal expansion and a primary surface-tension value.