Krytox GPL 205 PTFE-thickened PFPE grease GPL 205

spore: profile
id: krytox-gpl-205
spore_version: 0.2
family: perfluoropolyether-greases
name: Krytox GPL 205 PTFE-thickened PFPE grease
abbreviation: GPL 205
role: general-purpose grease for bearings, valves and seals
category: tribology
type: greases
summary: |
  Krytox GPL 205 is a PTFE-thickened perfluoropolyether (PFPE) grease made by Chemours, with NLGI grade 2 consistency and a base oil viscosity of 160 cSt at 40 °C. Chemours gives an estimated useful range of -36 °C to 204 °C for it, and a maximum oil volatility of 7 % in 22 hours at 204 °C under ASTM D2595. Chemours describes the grease as nonflammable and rates it H-1 for incidental food contact. No flight, outgassing or vacuum test value for this grade was found in the sources read.
best_for: Bearings, valves and seals from -36 °C to 204 °C where a non-reactive grease with H-1 incidental food-contact approval is needed (Chemours typical properties)
weakest_at: 'Oil loss at high temperature: 7 % oil volatility in 22 hours at 204 °C (ASTM D2595, Chemours typical value). No vacuum outgassing value for this grade was found'
identity:
  formula: F-[CF(CF3)-CF2-O]n-CF2CF3, n = 10 to 60 (PFPE base oil), thickened with PTFE (CF2-CF2)n
  cas: 60164-51-4
  source: krytox-wikipedia
  where: 'Lead section: structure, degree of polymerisation and CAS number of the Krytox PFPE family. The CAS number is the family number; a CAS number for GPL 205 itself was not found'
  designations:
    - system: Trade name
      code: Krytox GPL 205
      source: miller-gpl205
      where: Product page title and product details
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
    - propulsion-and-tanks
properties:
  - benchmark: min_service_temp
    label: Estimated useful range, lower limit, Krytox GPL 205
    value: -36
    unit: °C
    scope: material
    conditions:
      grade: Krytox GPL 205 (H-1) grease
      basis: 'Chemours footnote 3: based on pour point and where evaporation is approximately 10 %'
    method: Typical value printed on the Miller-Stephenson product page, not a specification limit. The Chemours table (footnote 1) prints the same lower limit with an en-dash minus sign
    status: ground
    source: miller-gpl205
    where: Summary section, sentence giving the estimated useful temperature range (-36°C to 204°C)
  - benchmark: max_service_temp
    label: Estimated useful range, upper limit, Krytox GPL 205
    value: 204
    unit: °C
    scope: material
    conditions:
      grade: Krytox GPL 205 (H-1) grease
      basis: 'Chemours footnote 3: based on pour point and where evaporation is approximately 10 %'
    method: Typical value printed by the manufacturer, not a specification limit (Chemours footnote 1). The Chempoint GPL performance article prints the same range
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Estimated Useful Range row, °C, column 205 (H-1)
  - benchmark: iso_viscosity_grade
    label: ISO viscosity grade of the base oil
    value: 150
    unit: '-'
    scope: material
    conditions:
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made (Miller-Stephenson product page)
    method: Typical value printed by the manufacturer; the table prints one value per column for the oil and the grease of the same number
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, ISO Grade of Oil row, column 105 (H-1) and 205 (H-1)
  - benchmark: nlgi_grade
    label: NLGI consistency grade, standard grade
    value: 2
    unit: '-'
    scope: material
    conditions:
      penetration_as_printed: 265–295 (the page prints no unit for penetration)
      basis: Standard grade; softer or harder grades can be made by special order
    method: Standard consistency stated by the manufacturer; the Chempoint product page prints NLGI Grade 2 for the same grade
    status: ground
    source: chemours-typical-props
    where: Overview text, paragraph beginning The standard grease consistency is NLGI grade 2
  - benchmark: kinematic_viscosity
    label: Base oil kinematic viscosity at 40 °C
    value: 160
    unit: cSt
    scope: material
    conditions:
      temperature: 40 °C
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value; Chemours states viscosity may vary within ±10 % (footnote 1)
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Viscosity cSt, 40 °C row, column 205 (H-1)
  - benchmark: kinematic_viscosity
    label: Base oil kinematic viscosity at 100 °C
    value: 18
    unit: cSt
    scope: material
    conditions:
      temperature: 100 °C
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value; Chemours states viscosity may vary within ±10 % (footnote 1)
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Viscosity cSt, 100 °C row, column 205 (H-1)
  - benchmark: kinematic_viscosity
    label: Base oil kinematic viscosity at 204 °C
    value: 3.1
    unit: cSt
    scope: material
    conditions:
      temperature: 204 °C
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value; Chemours states viscosity may vary within ±10 % (footnote 1)
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Viscosity cSt, 204 °C row, column 205 (H-1)
  - benchmark: viscosity_index
    label: Base oil viscosity index
    value: 124
    unit: '-'
    scope: material
    conditions:
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value printed by the manufacturer; no test method printed
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Viscosity Index row, column 205 (H-1)
  - benchmark: oil_density
    label: Base oil density at 0 °C
    value: 1.94
    unit: g/mL
    scope: material
    conditions:
      temperature: 0 °C
      basis: Base oil column 105 (H-1); the density of the grease itself is not printed
    method: Typical value printed by the manufacturer
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Density g/mL, 0 °C row, column 205 (H-1)
  - benchmark: oil_density
    label: Base oil density at 100 °C
    value: 1.76
    unit: g/mL
    scope: material
    conditions:
      temperature: 100 °C
      basis: Base oil column 105 (H-1); the density of the grease itself is not printed
    method: Typical value printed by the manufacturer
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Density g/mL, 100 °C row, column 205 (H-1)
  - benchmark: oil_volatility
    label: Maximum oil volatility, ASTM D2595, at 121 °C
    value: 1
    unit: '%'
    scope: material
    conditions:
      temperature: 121 °C
      time: 22 hours
      test: ASTM D2595
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value printed by the manufacturer under the stated ASTM test
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Maximum Oil Volatility ASTM D2595, % in 22 hr, 121 °C row, column 205 (H-1)
  - benchmark: oil_volatility
    label: Maximum oil volatility, ASTM D2595, at 204 °C
    value: 7
    unit: '%'
    scope: material
    conditions:
      temperature: 204 °C
      time: 22 hours
      test: ASTM D2595
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value printed by the manufacturer under the stated ASTM test
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Maximum Oil Volatility ASTM D2595, % in 22 hr, 204 °C row, column 205 (H-1)
  - benchmark: oil_separation
    label: Oil separation from grease, ASTM D6184, at 99 °C
    value: 5
    unit: '% (wt loss)'
    scope: material
    conditions:
      temperature: 99 °C
      time: 30 hours
      test: ASTM D6184
      basis: Base oil column 105 (H-1), from which the GPL 205 grease is made
    method: Typical value printed by the manufacturer under the stated ASTM test
    status: ground
    source: chemours-typical-props
    where: Typical Properties table, Oil Separation from Grease ASTM D6184, wt loss % in 30 hr, 99 °C row, column 205 (H-1)
  - benchmark: melting_point
    label: Melting point of the PTFE thickener
    value: 325
    unit: °C
    scope: material
    conditions:
      component: PTFE thickener, not the grease
      unit_as_printed: 325 °C (617 °F)
    method: Value printed by the manufacturer in the Overview text
    status: ground
    source: chemours-typical-props
    where: Overview text, paragraph on the PTFE thickener, melting point sentence
corrosion:
  - environment: Oxygen at high pressure
    headline: Chemours says Krytox lubricants resist degradation from oxygen at pressures above 3,000 psi (207 bar).
    effect: The Chemours article states that Krytox lubricants resist degradation from oxygen at pressures greater than 3,000 psi (207 bar), and it names no grade.
    conditions:
      basis: General statement for Krytox lubricants, not a GPL 205 test result
    source: chemours-reactive-gas
    where: Oxygen section
    rating: unknown
  - environment: Heat, 22 hours at 204 °C (oil evaporation)
    headline: The base oil of GPL 205 loses 7 % by evaporation in 22 hours at 204 °C under ASTM D2595.
    effect: At 121 °C the same test gives 1 %, so evaporation rises sharply between the two temperatures. This is the main ageing measure printed for the grade.
    conditions:
      basis: Typical value for the base oil column 105 (H-1); the grease itself was not tested in the source
    source: chemours-typical-props
    where: Typical Properties table, Maximum Oil Volatility ASTM D2595 rows, column 205 (H-1)
    rating: unknown
  - environment: Heat, 30 hours at 99 °C (oil separation)
    headline: Oil separation from GPL 205 is 5 % weight loss in 30 hours at 99 °C under ASTM D6184.
    effect: Oil separation from the grease is the loss of base oil from the thickener over time at temperature, and it is printed as a typical value.
    conditions:
      basis: Typical value for the base oil column 105 (H-1); the source prints no test at higher temperature for this grade
    source: chemours-typical-props
    where: Typical Properties table, Oil Separation from Grease ASTM D6184 rows, column 205 (H-1)
    rating: unknown
  - environment: Chemicals and radiation (general Krytox claims)
    headline: The Krytox PFPE family is described as thermally stable, nonflammable, insoluble in water and most solvents, and radiation resistant, with no numbers given.
    effect: The Wikipedia article and the Miller-Stephenson sheet state chemical and radiation resistance for the Krytox family. The Miller-Stephenson sheet adds that Krytox is compatible with plastics, elastomers, metals and ceramics.
    conditions:
      basis: General statements for the Krytox family; no test condition printed
    source: krytox-wikipedia
    where: Lead section, uses and properties paragraph
    rating: unknown
risks:
  hazards:
    - text: Chemours calls Krytox nonflammable, and the 2004 DuPont MSDS for Krytox PFPE oils gives a PMCC flash point of Does not ignite for the oils. That MSDS covers the oils, not the GPL 205 grease.
      ghs: []
      source: dupont-msds-pfpe-oils
      where: Fire Fighting Measures, Flammable Properties
    - text: Eye contact may cause irritation with discomfort, tearing or blurring of vision; skin contact may cause reddening. The DuPont MSDS says the product was not a skin irritant or sensitizer in a 100-person human patch test.
      ghs: []
      source: dupont-msds-pfpe-oils
      where: Hazards Identification, Potential Health Effects
    - text: Overheated or burning product releases fluorine-containing decomposition products that may cause lung irritation and pulmonary edema, which require medical treatment.
      ghs: []
      source: dupont-msds-pfpe-oils
      where: Hazards Identification, Potential Health Effects
    - text: The manufacturer warns of mild skin and eye irritation, and says contact with hot surfaces above 260 °C can produce fumes that cause coughing or respiratory irritation.
      ghs: []
      source: krytox-wikipedia
      where: Safety section
  failure_risks:
    - mode: Overheating above 260 °C
      trigger: Contact with hot surfaces above 260 °C (500 °F), as the manufacturer warns in the Wikipedia Safety section
      consequence: Fumes that cause coughing or respiratory irritation; at flame temperatures, toxic fluorine compounds (DuPont MSDS)
      source: krytox-wikipedia
      where: Safety section
    - mode: Oil loss by evaporation
      trigger: Operation at 204 °C for 22 hours (ASTM D2595)
      consequence: 7 % of the base oil evaporates in the test (Chemours typical value for the base oil column 105 (H-1))
      source: chemours-typical-props
      where: Typical Properties table, Maximum Oil Volatility ASTM D2595, 204 °C row, column 205 (H-1)
  side_effects: []
  handling:
    - text: Use ventilation when the oil is heated above 550 degF, and keep away from heat and flames (DuPont MSDS, Exposure Controls).
      source: dupont-msds-pfpe-oils
    - text: Keep the container tightly closed, and keep it away from heat and flames to avoid decomposition products (DuPont MSDS, Storage).
      source: dupont-msds-pfpe-oils
    - text: Avoid contact with eyes and skin and wash thoroughly after handling; the DuPont MSDS treats PFPE oils as inert and of low toxicity (Handling, personnel).
      source: dupont-msds-pfpe-oils
  mitigations: []
uses:
  - application: mechanisms
    device: Bearings, gears, valves, hinges and seals
    example: Miller-Stephenson lists bearings, O-rings, valves, hinges, handles, moving parts, seals, connectors, rollers, automotive interiors, fittings and gearboxes among GPL 205 applications.
    source: miller-gpl205
    where: Application tab list
  - application: propulsion-and-tanks
    device: Liquid-oxygen pump bearing housings and valves in oxygen service
    example: The Miller-Stephenson Krytox sheet lists LOX pump bearing housings and valves and O-rings in oxygen service under Aerospace, for the Krytox GPL grease family. The sheet does not tie these uses to GPL 205 alone.
    source: miller-tds-krytox
    where: Applications panel, Aerospace column
supply:
  - subject: Krytox PFPE base oil and grease
    demand: Krytox lubricants are sold as oils and greases for many applications and in laboratories, including high-vacuum work (Krytox Wikipedia, lead section). No production volume was found for the grade.
    routes: The oils are ethers of hexafluoropropylene oxide with a degree of polymerisation of 10 to 60, and the grease is the oil thickened with PTFE (Krytox Wikipedia, lead section).
    producers: []
    critical_lists: []
    substitutes:
      - 'Named in Wikipedia as another PFPE lubricant line: the Solvay Fomblin range (not compared here)'
    abundance: Not found in any source held
    source: krytox-wikipedia
    where: Lead section
  - subject: Manufacturer
    demand: The Chemours Company holds the Krytox trademark (Wikipedia, lead section). The sources read give no manufacturing location, country share or production volume for GPL 205.
    routes: []
    producers: []
    critical_lists: []
    substitutes: []
    abundance: Not found in any source held
    source: krytox-wikipedia
    where: Lead section; the article gives no manufacturing location
media: []
documents:
  - title: Typical Properties of Krytox General-Purpose Oils and Greases, Chemours, C-10296 (9/15)
    type: datasheet
    url: https://cdn.shopify.com/s/files/1/0519/4733/9937/files/Chemours_Krytox_Typical_Properties_Greases.pdf
    year: 2015
  - title: Miller-Stephenson product page, Krytox GPL 205 grease
    type: datasheet
    url: https://miller-stephenson.com/?p=789
  - title: Chempoint product page, Krytox GPL 205 grease (Chemours SKU 0124091)
    type: datasheet
    url: https://www.chempoint.com/products/chemours/krytox-greases/krytox-greases-for-general-purpose-applications/krytox-gpl205-grease
  - title: Miller-Stephenson Krytox Tri-Fold, general-purpose oils and greases
    type: datasheet
    url: https://www.miller-stephenson.com/wp-content/uploads/2019/10/TDS_Krytox-Tri-Fold.pdf
  - title: DuPont Material Safety Data Sheet, Krytox PFPE Oils, CEC01461, revised 10-Aug-04
    type: sds
    url: https://uwaterloo.ca/giga-to-nanoelectronics-centre/sites/default/files/uploads/files/krytoxpfpeoils.pdf
    year: 2004
  - title: NIST Atomic Weights and Isotopic Compositions, carbon
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=C&all=all&ascii=html
  - title: NIST Atomic Weights and Isotopic Compositions, fluorine
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=F&all=all&ascii=html
  - title: NIST Atomic Weights and Isotopic Compositions, oxygen
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=O&all=all&ascii=html
gaps:
  - Density of the GPL 205 grease itself is not printed; only the base oil density is recorded, as oil_density.
  - Flash point and evaporation for the GPL 205 grease were not found. The only flash point read is the 2004 DuPont MSDS for Krytox PFPE oils (Does not ignite, PMCC), which covers the oils, not this grease.
  - No oxygen compatibility test result for GPL 205 was read. Chemours names ASTM D2512, ASTM G72, ASTM D2863 and MIL-PRF-27617 for Krytox lubricants but prints no pass or fail or numeric result for GPL 205.
  - No vacuum outgassing value (TML, CVCM or similar) for GPL 205 was found in any NASA or ESA source read. The NASA outgassing database was not searched in this run.
  - No current Chemours SDS for GPL 205 was read. The Silmid copy needs a sign-in, and the lklab copy is in Korean.
  - 'Supply: no production site, country share, critical-mineral listing or feedstock tonnage for PFPE, hexafluoropropylene oxide or fluorspar was found in a source held.'
  - Chemical resistance for GPL 205 was not read beyond the manufacturer's general claims (chemically inert and nonreactive; compatible with plastics, elastomers, metals and ceramics).
  - Radiation and UV ageing data for GPL 205 were not read. The Wikipedia article and the Miller-Stephenson sheet state radiation resistance without numbers.
  - Thickener particle size is printed as 0.2 m in the Chemours PDF, with the micro sign lost in the text, so it is not recorded.
  - 'Property names not in spores/property-canon.yaml, used as short snake_case names: kinematic_viscosity, viscosity_index, iso_viscosity_grade, nlgi_grade, pour_point, oil_density, oil_volatility and oil_separation.'
  - The CAS number 60164-51-4 is the Krytox PFPE family number given in the Wikipedia lead. A CAS number for GPL 205 itself was not found.
  - Penetration (265 to 295) is printed without a unit, so it is recorded in conditions only.
  - No space, flight or lunar use data for GPL 205 were found. The aerospace and radiation statements are general claims for the Krytox family.
  - No photograph or diagram with a verified licence was read, so media is empty.
  - Base oil pour point of -36 °C is printed in the Chemours table with an en-dash minus sign, which the value check cannot match, so it is not recorded as a property.
sources:
  chemours-typical-props:
    title: Typical Properties of Krytox General-Purpose Oils and Greases, Chemours, C-10296 (9/15)
    id: Chemours table, columns 105 (H-1) and 205 (H-1); replaces H-58510-7
    url: https://cdn.shopify.com/s/files/1/0519/4733/9937/files/Chemours_Krytox_Typical_Properties_Greases.pdf
    year: 2015
    kind: datasheet
    license: manufacturer datasheet, linked not reproduced; hosted on a Shopify CDN, not on chemours.com
  miller-gpl205:
    title: Krytox GPL 205 grease, Miller-Stephenson product page
    id: Product details, applications, specifications met (ASTM D2595, ASTM D6184, NSF H-1)
    url: https://miller-stephenson.com/?p=789
    kind: web
    license: distributor web page, linked not reproduced
  chempoint-gpl205:
    title: Krytox GPL 205 grease, Chempoint product page (Chemours SKU 0124091)
    id: Product specifications and application list
    url: https://www.chempoint.com/products/chemours/krytox-greases/krytox-greases-for-general-purpose-applications/krytox-gpl205-grease
    kind: web
    license: distributor web page, linked not reproduced
  chemours-gpl-performance:
    title: Chemours Krytox GPL performance, Chempoint article
    id: GPL 200 series table, estimated temperature range and oil viscosity
    url: https://www.chempoint.com/en-ca/insights/chemours-krytox-gpl-performance
    kind: web
    license: distributor article, linked not reproduced
  chemours-reactive-gas:
    title: Specifying Grease and Oil for Reactive Gas Environments, Chemours Krytox article (Chempoint)
    id: Oxygen, chlorine and fluorine service statements
    url: https://www.chempoint.com/en-ca/insights/chemours-krytox-lubricants-for-reactive-gas-enviro
    kind: web
    license: distributor article, linked not reproduced
  krytox-wikipedia:
    title: Krytox, Wikipedia
    id: Article lead, structure, uses, safety section
    url: https://en.wikipedia.org/wiki/Krytox
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
  dupont-msds-pfpe-oils:
    title: DuPont Material Safety Data Sheet, Krytox PFPE Oils, CEC01461
    id: Corporate MSDS DU002670, revised 10-Aug-04, printed 13.08.2004
    url: https://uwaterloo.ca/giga-to-nanoelectronics-centre/sites/default/files/uploads/files/krytoxpfpeoils.pdf
    year: 2004
    kind: datasheet
    license: archived supplier SDS, linked not reproduced
  miller-tds-krytox:
    title: Krytox Tri-Fold, Miller-Stephenson general-purpose oils and greases
    id: Applications panel (Aerospace, Chemical Manufacturing, Vacuum and Optics columns)
    url: https://www.miller-stephenson.com/wp-content/uploads/2019/10/TDS_Krytox-Tri-Fold.pdf
    kind: datasheet
    license: distributor sheet, linked not reproduced
  nist-carbon:
    title: NIST Atomic Weights and Isotopic Compositions, carbon
    id: Standard atomic weight [12.0096, 12.0116]
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=C&all=all&ascii=html
    kind: database
    license: US government data
  nist-fluorine:
    title: NIST Atomic Weights and Isotopic Compositions, fluorine
    id: Atomic weight 18.998 403 162 73(92)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=F&all=all&ascii=html
    kind: database
    license: US government data
  nist-oxygen:
    title: NIST Atomic Weights and Isotopic Compositions, oxygen
    id: Standard atomic weight [15.999 03, 15.999 77]
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=O&all=all&ascii=html
    kind: database
    license: US government data
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 2
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-11-01 from the pages named in each entry. The Chemours typical-properties table is hosted on a Shopify CDN, not chemours.com, and its values are typical, not specifications. The oil values are for the base oil column 105 (H-1), from which the GPL 205 grease is made; Chemours prints them in the same column as the grease. Unreachable: the Silmid SDS (sign-in required) and the current Chemours SDS (not found in English). The estimated useful range is a Chemours estimate based on pour point and 10 % evaporation.'
story:
  recipe:
    line: Krytox GPL 205 is a grease made from a perfluoropolyether (PFPE) base oil, the GPL 105 oil, thickened with polytetrafluoroethylene (PTFE) powder. The PFPE chain is saturated and contains only carbon, oxygen and fluorine, and its repeat unit is CF(CF3)-CF2-O (Chemours Overview; Krytox Wikipedia, lead).
    parts:
      - name: Carbon
        symbol: C
        role: 'Three carbons per repeat unit CF(CF3)CF2O: one in the CF backbone site, one in the CF2 site and one in the CF3 side group'
        share_note: Atomic weight [12.0096, 12.0116] (NIST). Chemours prints a typical oil composition by weight in its Overview; it is not recorded here.
      - name: Fluorine
        symbol: F
        role: 'Six fluorines per repeat unit: one on the CF site, three on the CF3 group and two on the CF2 site'
        share_note: Atomic weight 18.998 403 162 73(92) (NIST).
      - name: Oxygen
        symbol: O
        role: One ether oxygen per repeat unit
        share_note: Atomic weight [15.999 03, 15.999 77] (NIST).
  risk_groups:
    - title: For people
      lead: The DuPont MSDS treats the PFPE oils as inert and of low toxicity, and the hazards in the sources read come from overheating.
      level: 1
      verdict: Low hazard in use; overheating is the main hazard
      points:
        - label: Skin and eyes
          line: The DuPont MSDS says eye contact may cause irritation and the product was not a skin irritant in a 100-person patch test.
        - label: Overheating
          line: Above 260 °C, fumes that cause coughing or respiratory irritation can form (Wikipedia, manufacturer warning), and flame temperatures release fluorine compounds (DuPont MSDS).
    - title: If it fails
      lead: The failure route in these sources is oil loss at high temperature, measured as a typical value.
      points:
        - label: Oil volatility
          line: At 204 °C the base oil loses 7 % in 22 hours under ASTM D2595, against 1 % at 121 °C (Chemours typical value).
  why: Krytox GPL 205 is a PTFE-thickened PFPE grease with an estimated useful range of -36 °C to 204 °C, a base oil viscosity of 160 cSt at 40 °C and NLGI grade 2 consistency, all as printed by Chemours. Its PTFE thickener melts at 325 °C. Chemours describes the grease as nonflammable and rates it H-1 for incidental food contact, which is why it is sold for general-purpose use where a non-reactive grease is wanted. No space, vacuum or oxygen test value for this grade was found in the sources read.
  uses:
    - where: General industry and maintenance
      line: Chempoint lists facility infrastructure (compressors) and maintenance of bearings, chains, electric motors and gearboxes as uses of the GPL 205 grease. Chemours says the grease is commonly used to reduce noise, vibration and harshness in automotive parts.
    - where: Aerospace and oxygen service (Krytox grease family)
      line: The Miller-Stephenson sheet lists valves and O-rings in oxygen service and LOX pump bearing housings under aerospace for the Krytox GPL grease family. The sheet does not tie these uses to GPL 205 alone.
  can_do:
    - label: Run from -36 °C to 204 °C
      value: '-36 °C to 204 °C estimated useful range'
      benchmark: min_service_temp
      line: The Chemours typical-properties table gives an estimated useful range of -36 °C to 204 °C for GPL 205 (column 205 (H-1)). The Miller-Stephenson product page prints the same range.
    - label: Hold a standard consistency
      value: NLGI grade 2 (penetration 265–295)
      benchmark: nlgi_grade
      line: Chemours states that the standard grease consistency is NLGI grade 2, penetration 265–295, with softer or harder grades available by special order.
    - label: Limited oil loss at 121 °C
      value: 1 % oil volatility in 22 hours at 121 °C
      benchmark: oil_volatility
      line: The same table gives a maximum oil volatility of 1 % in 22 hours at 121 °C under ASTM D2595, rising to 7 % at 204 °C.
  compare: Within the Chemours GPL 200 series, GPL 205 has a heavier base oil than the GPL 200 to 204 grades and a higher upper useful-range limit than those grades (Chemours typical properties; Chempoint GPL performance article). The series values are for Krytox grades only, so the sources cannot rank GPL 205 against non-Krytox greases.
  compare_rows:
    - scope: material
      label: Estimated useful range, upper limit
      benchmark: max_service_temp
    - scope: material
      label: PTFE thickener melting point
      benchmark: melting_point
    - scope: material
      label: Oil volatility at 204 °C
      benchmark: oil_volatility
  handling:
    - Use ventilation when the oil is heated above 550 degF (DuPont MSDS).
    - Keep containers closed and away from heat and flames to avoid decomposition products.
    - Avoid contact with eyes and skin and wash after handling.
    - Quote the grade in full (GPL 205, H-1) when specifying, since the H-1 approval applies only to grades with the H-1 mark.
  good_for:
    - Bearings and valves from -36 °C to 204 °C where a non-reactive grease is needed (Chemours says the Krytox family is chemically inert and nonreactive).
    - 'Food-contact sites: H-1 incidental food contact approval is printed for GPL 205 (Chemours table; Miller-Stephenson page).'
    - 'Oxygen service: Chemours and Miller-Stephenson describe the Krytox family as safe for oxygen service, but no GPL 205 test result was read.'
  watch_out:
    - 'High temperature: 7 % oil volatility in 22 hours at 204 °C (ASTM D2595) means base oil is lost near the top of the range.'
    - No vacuum outgassing, flight or radiation data for GPL 205 was found, so space use needs a test on the grease itself.
    - The 2004 DuPont MSDS covers the PFPE oils, not this grease, and no current Chemours SDS for GPL 205 was read.
    - Heating above 260 °C can release fumes (Wikipedia, manufacturer warning).
  verdict: Krytox GPL 205 is a PTFE-thickened PFPE grease with an estimated useful range of -36 °C to 204 °C, NLGI grade 2 consistency and H-1 incidental food-contact approval, as printed by Chemours. Its base oil loses 7 % in 22 hours at 204 °C, and no space, vacuum or oxygen test value for this grade was found in the sources read.