spore: profile
id: silvered-fep-teflon
spore_version: 0.2
family: fluoropolymer-mirror
name: Silvered FEP Teflon
abbreviation: Ag/FEP
role: second-surface mirror thermal control film
category: coatings
type: optical-solar-reflectors
summary: |
  Silvered FEP Teflon is a flexible second-surface mirror: a fluorinated ethylene propylene (FEP) film with silver and Inconel vapour-deposited on its back. Dunmore prints a typical outside-surface value of 0.13 to 0.16 for the solar absorptance and emittance pair, without splitting them, and an operating range of -185 to 125 °C. SatCatalog prints an operating range of -150 to 125 °C. In a NASA plasma-asher test, the SiOx-coated version darkened and was removed after an atomic-oxygen fluence of 1.1x10^22 atoms/cm2. Film flown on LDEF lost more than 0.001 inch of its nominal 0.005 inch thickness in its most exposed rows.
best_for: Flexible spacecraft thermal control where a low ratio of solar absorptance to emittance is needed, over a published range of -185 to 125 °C (Dunmore)
weakest_at: 'Atomic oxygen in low Earth orbit: the FEP erodes, and the SiOx barrier only protects where it has not cracked (NASA TM 106146 and NASA TM 104096)'
identity:
  formula: Laminate of FEP film (tetrafluoroethylene and hexafluoropropylene copolymer), vapour-deposited silver and Inconel, bonded with a pressure-sensitive adhesive
  source: nasa-tm104096
  where: Introduction, description of the blanket material; monomers from the Wikipedia FEP article (composition only)
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - ultraviolet
    - vacuum-and-outgassing
  applications:
    - thermal-control
properties:
  - benchmark: alpha_epsilon_outside_surface
    label: Typical outside surface solar absorptance / emittance value
    value: 0.13
    value_high: 0.16
    bound: range
    unit: '-'
    scope: material
    conditions:
      product: silvered FEP Teflon, outside surface
      split: the page prints one combined pair and does not separate solar absorptance from emittance
      test: not stated
    method: Value printed on the Dunmore product page
    status: ground
    source: dunmore-silver-fep
    where: Product page, typical outside surface values line
  - benchmark: max_service_temp
    label: Operating temperature, upper limit (Dunmore)
    value: 125
    unit: °C
    scope: material
    conditions:
      product: silvered FEP Teflon
      basis: operating temperature range as printed
    method: Value printed on the Dunmore product page
    status: ground
    source: dunmore-silver-fep
    where: Product page, operating temperature line (-185 °C to 125 °C)
  - benchmark: min_service_temp
    label: Operating temperature, lower limit (Dunmore)
    value: -185
    unit: °C
    scope: material
    conditions:
      product: silvered FEP Teflon
      basis: operating temperature range as printed
    method: Value printed on the Dunmore product page
    status: ground
    source: dunmore-silver-fep
    where: Product page, operating temperature line (-185 °C to 125 °C)
  - benchmark: max_service_temp
    label: Operating temperature, upper limit (SatCatalog)
    value: 125
    unit: °C
    scope: material
    conditions:
      product: silvered FEP Teflon
      basis: operating temperature range as printed
    method: Value printed on the SatCatalog component page
    status: ground
    source: satcatalog-silver-teflon
    where: Overview section, operating temperature range (-150 °C to 125 °C)
  - benchmark: min_service_temp
    label: Operating temperature, lower limit (SatCatalog)
    value: -150
    unit: °C
    scope: material
    conditions:
      product: silvered FEP Teflon
      basis: operating temperature range as printed; differs from the Dunmore lower limit of -185 °C
    method: Value printed on the SatCatalog component page
    status: ground
    source: satcatalog-silver-teflon
    where: Overview section, operating temperature range (-150 °C to 125 °C)
  - benchmark: reflectance
    label: Reflectance
    value: 90
    bound: lower
    unit: '%'
    scope: material
    conditions:
      basis: printed as Reflectance >90%; wavelength and reflectance type not stated
    method: Value printed on the SatCatalog component page
    status: ground
    source: satcatalog-silver-teflon
    where: Overview section, Optical Performance
  - benchmark: normal_emittance
    label: Normal emittance
    value: 40
    value_high: 80
    bound: range
    unit: '%'
    scope: material
    conditions:
      basis: printed as 40-80% depending on film thickness; the page does not pair each value with a thickness
    method: Value printed on the SatCatalog component page
    status: ground
    source: satcatalog-silver-teflon
    where: Overview section, Optical Performance
  - benchmark: film_thickness
    label: Film thickness range
    value: 50
    value_high: 250
    bound: range
    unit: μm
    scope: material
    conditions:
      product: silvered FEP Teflon film
      basis: range as printed; not a single thickness
    method: Value printed on the Dunmore product page
    status: ground
    source: dunmore-silver-fep
    where: Product page, film thickness line
  - benchmark: maximum_film_width
    label: Maximum film width
    value: 24
    unit: inches
    scope: material
    conditions:
      basis: printed as maximum film width under Customization
    method: Value printed on the SatCatalog component page
    status: ground
    source: satcatalog-silver-teflon
    where: Overview section, Customization
  - benchmark: silver_layer_thickness
    label: Vapour-deposited silver layer
    value: 1600
    unit: Å
    scope: material
    conditions:
      basis: nominal, as printed for the LDEF blanket material
      layer: silver on the back of the FEP film
    method: Value printed in the NASA description of the blanket
    status: ground
    source: nasa-tm104096
    where: Introduction, description of the blanket (approximately 1600A of vapor deposited silver)
  - benchmark: inconel_layer_thickness
    label: Vapour-deposited Inconel layer
    value: 400
    unit: Å
    scope: material
    conditions:
      basis: nominal, as printed for the LDEF blanket material
      layer: Inconel over the silver
    method: Value printed in the NASA description of the blanket
    status: ground
    source: nasa-tm104096
    where: Introduction, description of the blanket (approximately 400A of vapor deposited inconel)
  - benchmark: ao_erosion_depth
    label: FEP film loss in LDEF Rows 8 to 10
    value: 0.001
    bound: lower
    unit: inch
    scope: material
    conditions:
      exposure: 5 years 9 months in low Earth orbit on LDEF, most extreme rows 8 to 10
      starting_thickness: 0.005 inch nominal FEP film
      note: printed as in excess of 0.001 inch
    method: Preliminary estimate by the authors
    status: ground
    source: nasa-tm104096
    where: Discussion of LDEF film erosion, paragraph beginning Preliminary estimates
  - benchmark: melting_point
    label: Melt point of the bare FEP film
    value: 260
    value_high: 280
    bound: range
    unit: °C
    scope: material
    conditions:
      form: bare Teflon FEP film, 1 mil (0.025 mm) basis, not the silvered blanket
      test: ASTM D3418 (DTA)
    method: Value printed in the Typical Properties table
    status: ground
    source: chemours-fep-bulletin
    where: Typical Properties table, Thermal section, Melt Point (printed 260–280 °C)
  - benchmark: zero_strength_temperature
    label: Zero strength temperature of the bare FEP film
    value: 255
    unit: °C
    scope: material
    conditions:
      form: bare Teflon FEP film, 1 mil basis
      load: temperature at which a film supports 0.14 N/mm2 (20 psi) for 5 sec, per the bulletin footnote
    method: Value printed in the Typical Properties table
    status: ground
    source: chemours-fep-bulletin
    where: Typical Properties table, Thermal section, Zero Strength Temperature
  - benchmark: max_service_temp
    label: Continuous service temperature, upper limit (bare FEP film)
    value: 205
    unit: °C
    scope: material
    conditions:
      form: bare Teflon FEP film resin, not the silvered blanket
      basis: continuous service range as printed
    method: Value printed in the bulletin description bullets
    status: ground
    source: chemours-fep-bulletin
    where: Description bullets, continuous service temperature (–240 to 205 °C)
  - benchmark: density
    label: Density of the bare FEP film
    value: 2150
    unit: kg/m3
    scope: material
    conditions:
      form: bare Teflon FEP film, 1 mil basis
      test: ASTM D1505
    method: Value printed in the Miscellaneous table
    status: ground
    source: chemours-fep-bulletin
    where: Miscellaneous table, Density
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at break of the bare FEP film
    value: 21
    unit: N/mm2
    scope: material
    conditions:
      form: bare Teflon FEP film, 1 mil (0.025 mm) basis at 25 °C
      test: ASTM D882
    method: Value printed in the Mechanical table
    status: ground
    source: chemours-fep-bulletin
    where: Mechanical table, Tensile Strength at Break (3000 psi)
  - benchmark: elongation
    label: Elongation at break of the bare FEP film
    value: 300
    unit: '%'
    scope: material
    conditions:
      form: bare Teflon FEP film, 1 mil (0.025 mm) basis at 25 °C
      test: ASTM D882
    method: Value printed in the Mechanical table
    status: ground
    source: chemours-fep-bulletin
    where: Mechanical table, Elongation at Break
  - benchmark: dielectric_constant
    label: Dielectric constant of the bare FEP film
    value: 2
    unit: '-'
    scope: material
    conditions:
      form: bare Teflon FEP film at 25 °C
      frequency: 100 Hz to 1 MHz
      test: ASTM D150
    method: Value printed in the Electrical table
    status: ground
    source: chemours-fep-bulletin
    where: Electrical table, Dielectric Constant
  - benchmark: refractive_index
    label: Refractive index of the bare FEP film
    value: 1.341
    value_high: 1.347
    bound: range
    unit: '-'
    scope: material
    conditions:
      form: bare Teflon FEP film
      test: ASTM D542
    method: Value printed in the Miscellaneous table
    status: ground
    source: chemours-fep-bulletin
    where: Miscellaneous table, Refractive Index
  - benchmark: solar_transmittance
    label: Solar transmission of the bare FEP film
    value: 96
    unit: '%'
    scope: material
    conditions:
      form: bare Teflon FEP film, 1 mil (0.025 mm) basis at 25 °C
      test: ASTM E-424
      note: the silvered blanket is opaque to solar transmission because of its silver layer
    method: Value printed in the Miscellaneous table
    status: ground
    source: chemours-fep-bulletin
    where: Miscellaneous table, Solar Transmission
  - benchmark: specific_heat
    label: Specific heat of the bare FEP film
    value: 1172
    unit: J/(kg·K)
    scope: material
    conditions:
      form: bare Teflon FEP film
    method: Value printed in the Thermal table
    status: ground
    source: chemours-fep-bulletin
    where: Thermal table, Specific Heat (0.28 Btu/(lb·°F))
  - benchmark: thermal_conductivity
    label: Thermal conductivity of the bare FEP film
    value: 0.195
    unit: W/(m·K)
    scope: material
    conditions:
      form: bare Teflon FEP film
      method_printed: Cenco-Fitch
    method: Value printed in the Thermal table
    status: ground
    source: chemours-fep-bulletin
    where: Thermal table, Coefficient of Thermal Conductivity
  - benchmark: total_mass_loss
    label: Total mass loss limit (ASTM E-595)
    value: 1
    bound: upper
    unit: '%'
    scope: material
    conditions:
      standard: ASTM E-595
      kind: qualification limit printed by the vendor, not a measured result for this product
    method: Limit printed on the SatCatalog component page (printed as TML <1.0%)
    status: ground
    source: satcatalog-silver-teflon
    where: Qualification and Testing section
  - benchmark: collected_volatile_condensable_material
    label: Collected volatile condensable material limit (ASTM E-595)
    value: 0.1
    bound: upper
    unit: '%'
    scope: material
    conditions:
      standard: ASTM E-595
      kind: qualification limit printed by the vendor, not a measured result for this product
    method: Limit printed on the SatCatalog component page (printed as CVCM <0.1%)
    status: ground
    source: satcatalog-silver-teflon
    where: Qualification and Testing section
corrosion:
  - environment: Atomic oxygen in low Earth orbit, simulated in an RF plasma asher
    headline: In NASA's plasma-asher test the SiOx/FEP/Ag sample darkened and was removed at 1.1x10^22 atoms/cm2.
    effect: At that fluence the sample's solar absorptance rose and its thermal emittance fell sharply. The sample turned into a black, tar-like film that began at its unprotected edges, where the silver and silicone adhesive oxidised. NASA states that atomic oxygen oxidises FEP, causing mass loss and surface texturing, and that the asher gives a random-direction attack, unlike the directed beam in orbit.
    rating: severe
    conditions:
      facility: RF oxygen plasma asher with intense VUV
      fluence: 1.1x10 22 atoms/cm2 at removal
      caveat: the test is not a direct lifetime prediction, because the asher attack is random
    source: nasa-tm106146
    where: Damage Mechanisms to Coatings; Exposure in an RF Plasma Asher; RF Plasma Asher Effects on Coatings
  - environment: Low Earth orbit in flight, LDEF, 5 years 9 months
    headline: Silvered FEP on LDEF lost more than 0.001 inch of its 0.005 inch film in the most exposed rows.
    effect: Atomic-oxygen erosion roughened the coating surface, and some pieces changed from specular to diffuse reflectors. XPS, infrared and thermal analysis found no significant change at the molecular level. The authors call the erosion extent unanticipated, and note that it was not uniform across the film.
    rating: severe
    conditions:
      exposure: 5 years 9 months on LDEF, Rows 8 to 10 (most extreme cases)
      note: the film-loss figure is a preliminary estimate
    source: nasa-tm104096
    where: Abstract; Discussion of LDEF film erosion
  - environment: Ultraviolet and vacuum-ultraviolet radiation in orbit
    headline: NASA's review says UV can embrittle FEP, degrade transmittance and cause mass loss over long exposure.
    effect: The review states that ultraviolet radiation may cause embrittlement, transmittance degradation and mass loss over a long exposure duration. It notes that atomic oxygen and UV act together on FEP, and that a SiOx coating does not stop UV that reaches the FEP through cracks.
    rating: moderate
    conditions:
      basis: statement in the NASA review; no UV dose or number is printed for this laminate
    source: nasa-tm106146
    where: Damage Mechanisms to Coatings, paragraph on SiOx/FEP/Ag
  - environment: Thermal cycling and micrometeoroid or debris impact
    headline: Cracks from thermal cycling let atomic oxygen reach the FEP, and impacts can delaminate the film.
    effect: NASA notes that cracks in the SiOx coating caused by thermal cycling let atomic oxygen and UV reach the FEP, changing its optical properties. LDEF showed delamination of FEP from the silver around impact sites, and exposed silicone adhesive at an impact site can form a dark contaminant with atomic oxygen and UV.
    rating: moderate
    conditions:
      thermal_cycling_in_test: 10 cycles between -93 °C and +49 °C in vacuum, before plasma-asher exposure
    source: nasa-tm106146
    where: Damage Mechanisms to Coatings; Vacuum Thermal Cycling Exposure
  - environment: Outgassing in vacuum
    headline: The SatCatalog page quotes ASTM E-595 limits of TML below 1.0% and CVCM below 0.1%.
    effect: These are qualification limits printed by the vendor catalog, not measured results for this product. The page does not give the test lot, date or specimen.
    rating: low
    conditions:
      standard: ASTM E-595
      basis: limits as printed on the SatCatalog page
    source: satcatalog-silver-teflon
    where: Qualification and Testing section
risks:
  hazards:
    - text: The bulk silver safety data sheet (Stanford Advanced Materials, product Silver, brand SAM, revision 09/04/2017) classifies silver as acute aquatic toxicity Category 1 (H400) and chronic aquatic toxicity Category 1 (H410), with signal word Warning and precautionary statement P273, avoid release to the environment.
      ghs:
        - H400
        - H410
      source: sds-silver-sam
      where: Sections 2.1 and 2.2
    - text: The same sheet prints an oral LD50 for silver in rat of more than 5,000 mg/kg (male), and 'No data available' for inhalation and dermal toxicity.
      ghs: []
      source: sds-silver-sam
      where: Section 11.1
    - text: The same sheet prints silver exposure limits of TWA 0.01 mg/m3 (OSHA Table Z-1) and TWA 0.1 mg/m3 (ACGIH TLV).
      ghs: []
      source: sds-silver-sam
      where: Section 8.1, control parameters
    - text: The Chemours FEP bulletin says the polymer is chemically inert and solvent resistant to virtually all chemicals, except molten alkali metals, gaseous fluorine and certain complex halogenated compounds at elevated temperatures and pressures.
      ghs: []
      source: chemours-fep-bulletin
      where: Chemical compatibility paragraph
  failure_risks:
    - mode: Atomic-oxygen attack through cracks in the SiOx barrier
      trigger: Cracks from thermal cycling in the SiOx coating, exposing the FEP
      consequence: Atomic oxygen and UV reach the FEP, changing its optical properties and the integrity of the coating (NASA TM 106146)
      severity: high
      source: nasa-tm106146
      where: Damage Mechanisms to Coatings
    - mode: Darkening and oxidation of unprotected edges
      trigger: Plasma-asher exposure to 1.1x10^22 atoms/cm2, with unprotected sample edges
      consequence: Solar absorptance rose and emittance fell sharply, and the silver and silicone adhesive oxidised into a black, tar-like film (NASA TM 106146)
      severity: high
      source: nasa-tm106146
      where: RF Plasma Asher Effects on Coatings
    - mode: Delamination around micrometeoroid or debris impacts
      trigger: Impacts in orbit
      consequence: FEP delaminated from the silver around impact sites on LDEF, and exposed silicone adhesive can form a dark deposit (NASA TM 106146)
      severity: moderate
      source: nasa-tm106146
      where: Damage Mechanisms to Coatings
    - mode: Erosion and roughening of the FEP surface
      trigger: Long exposure in low Earth orbit (LDEF, 5 years 9 months)
      consequence: Film lost more than 0.001 inch of 0.005 inch in the most exposed rows, and some pieces changed from specular to diffuse reflectors (NASA TM 104096)
      severity: high
      source: nasa-tm104096
      where: Abstract; Discussion of LDEF film erosion
  side_effects:
    - text: Atomic oxygen and UV acting together with silicones can produce a dark-coloured contaminant deposit on nearby surfaces (NASA TM 106146).
      affects: Nearby spacecraft surfaces
      source: nasa-tm106146
      where: Damage Mechanisms to Coatings
  handling:
    - text: 'Bulk silver: air sensitive; store under inert gas and keep in a dry place (safety data sheet, storage section). This applies to the silver metal, not to the finished film.'
      source: sds-silver-sam
      where: Section 7
    - text: Teflon FEP film is rated VTM-0 under ANSI/UL 94 with an oxygen index of 95% (ASTM D2863), per the bulletin, for the bare film at 1 mil.
      source: chemours-fep-bulletin
      where: Mechanical and Flammability rows of the Typical Properties table
  mitigations:
    - text: A SiOx barrier coat reduces atomic-oxygen attack on the FEP, but thermal-cycling cracks leave gaps in it (NASA TM 106146).
      source: nasa-tm106146
      where: Damage Mechanisms to Coatings
uses:
  - application: thermal-control
    device: Thermal control blanket on Space Station Freedom power-system radiators (candidate coating in NASA's test, not a flown product in this source)
    example: NASA tested SiOx-coated silvered Teflon with white paints and anodised aluminium as candidate radiator coatings for Space Station Freedom, against a 30-year design life.
    source: nasa-tm106146
    where: Introduction; Materials Tested
  - application: thermal-control
    device: Thermal blanket on LDEF experiment trays
    example: Silvered FEP thermal blankets provided thermal protection for experiments on LDEF Tray F2 and Trays C5, C8 and A10.
    source: nasa-tm104096
    where: Section 1, Introduction
  - application: thermal-control
    device: Flexible second-surface mirror in spacecraft thermal control
    example: NASA describes the blanket material, also known as flexible second-surface mirror thermal control coating, as used in a variety of space applications where thermal protection is a consideration.
    source: nasa-tm104096
    where: Section 1, Introduction
supply:
  - subject: Silver
    producers:
      - country: Mexico
        share_percent: 24.2
        year: 2025
      - country: Peru
        share_percent: 13.8
        year: 2025
      - country: China
        share_percent: 13.1
        year: 2025
      - country: Bolivia
        share_percent: 5.8
        year: 2025
      - country: Chile
        share_percent: 5.4
        year: 2025
    critical_lists:
      - list: USGS 2025 Final List of Critical Minerals (silver added)
        listed: true
      - list: EU critical raw materials list
        listed: false
    recycling: 'USGS: about 1,000 tons of silver was recovered from new and old scrap in 2025, about 11% of apparent consumption.'
    substitutes: []
    source: usgs-mcs2026-silver
    where: World Mine Production and Reserves table, 2025e (world total rounded 26,000 t). Shares calculated by Space Mushroom as printed tons divided by the rounded world total. Critical list change in the opening paragraph. Recycling paragraph.
documents:
  - title: 'Dunmore: Silver FEP film product page'
    type: datasheet
    url: https://www.dunmore.com/products/silver-fep-film.html
    year: 2026
  - title: 'SatCatalog: Silver Teflon FEP tape component page'
    type: database
    url: https://www.satcatalog.com/component/silver-teflon-fep-tape
    year: 2026
  - title: 'NASA TM 106146: The Effects of Simulated Low Earth Orbit Environments on Spacecraft Thermal Control Coatings (Dever et al., 1993)'
    type: report
    url: https://ntrs.nasa.gov/api/citations/19930017830/downloads/19930017830.pdf
    year: 1993
  - title: 'NASA TM 104096: An Analysis of LDEF-Exposed Silvered FEP Teflon Thermal Blanket Material (Young and Slemp, 1992)'
    type: report
    url: https://ntrs.nasa.gov/api/citations/19920005971/downloads/19920005971.pdf
    year: 1992
  - title: Teflon FEP Fluoropolymer Film Properties Bulletin (copy hosted by PolymerFilms)
    type: datasheet
    url: https://polymerfilms.com/wp-content/uploads/2023/06/Chemours-Teflon_FEP-Datasheet-cobranded-pf.pdf
    year: 2022
  - title: 'USGS Mineral Commodity Summaries 2026: Silver'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
  - title: 'Safety Data Sheet: Silver (Stanford Advanced Materials, brand SAM, version 3.0)'
    type: sds
    url: https://www.sputtertargets.net/wp-content/uploads/2018/05/Silver-Ag-sds.pdf
    year: 2017
gaps:
  - 'No flight-heritage details are verified: SatCatalog prints Heritage Yes without listing missions. The brief''s Hubble and ISS use is not confirmed by any page read in this run, so it is not in uses.'
  - Solar absorptance (alpha) and infrared emittance (epsilon) are not given separately. Dunmore prints one combined pair (0.13 to 0.16), and SatCatalog prints normal emittance of 40-80% by thickness without alpha.
  - The two operating ranges disagree on the lower limit (Dunmore -185 °C, SatCatalog -150 °C). Both are kept, each with its source. Neither is tied to a test standard.
  - The Dunmore page names an Inconel protective layer over the silver but does not print a SiOx layer, its thickness, the FEP thickness on the product, or the adhesive. SiOx and the Permacel P223 adhesive come from the NASA test samples only.
  - No atomic-oxygen erosion yield or solar absorptance and emittance change values for this material were read as numbers. NASA's test results are shown in figures only, so no value was taken from them.
  - The Wikipedia article says FEP contains about 5% of the 'propylene component'. The term is ambiguous, so the share was not used.
  - The FEP film's own thermal decomposition products and hazard statements were not found. PubChem's silver record was blocked by a reCAPTCHA and could not be read.
  - The silver safety data sheet is for bulk silver metal (brand SAM, revision 09/04/2017). The silvered film has no safety data sheet read in this run.
  - Silver abundance in the Earth's crust was not found in a page read in this run.
  - No supply data for FEP resin producers or feedstock was read. The supply section covers silver only.
  - The EU critical raw materials list status for silver was not checked.
  - No substitute for silvered FEP in thermal control was found in a page read in this run.
  - No standard grade designations apply to this coating. The bulletin's 'Teflon FEP' trade name is not listed as a designation.
  - No image with a confirmed licence was fetched, so media is not included.
  - Thermal-cycling and UV effects are described in NASA's text, but no numeric change for this laminate was read from the text.
  - The ASTM E-595 limits are quoted from SatCatalog and were not checked against the ASTM standard.
sources:
  dunmore-silver-fep:
    title: Dunmore, Silver FEP film product page
    id: Dunmore product page, silver-fep-film
    url: https://www.dunmore.com/products/silver-fep-film.html
    year: 2026
    kind: datasheet
    license: vendor web page, cited not reproduced
  satcatalog-silver-teflon:
    title: SatCatalog, Silver Teflon FEP tape component page (vendor SQUID3 Space)
    id: SatCatalog component silver-teflon-fep-tape
    url: https://www.satcatalog.com/component/silver-teflon-fep-tape
    year: 2026
    kind: database
    license: catalog web page, cited not reproduced
  nasa-tm106146:
    title: The Effects of Simulated Low Earth Orbit Environments on Spacecraft Thermal Control Coatings (NASA TM 106146, SAMPE 1993)
    id: NASA TM 106146; NTRS 19930017830
    url: https://ntrs.nasa.gov/api/citations/19930017830/downloads/19930017830.pdf
    year: 1993
    kind: report
    license: public domain (NASA)
  nasa-tm104096:
    title: An Analysis of LDEF-Exposed Silvered FEP Teflon Thermal Blanket Material (NASA TM 104096)
    id: NASA TM 104096; NTRS 19920005971
    url: https://ntrs.nasa.gov/api/citations/19920005971/downloads/19920005971.pdf
    year: 1992
    kind: report
    license: public domain (NASA)
  chemours-fep-bulletin:
    title: Teflon FEP Fluoropolymer Film Properties Bulletin (Chemours name; copy hosted by PolymerFilms, footer names Polymershapes)
    id: Teflon FEP film bulletin, 1 mil basis for typical values
    url: https://polymerfilms.com/wp-content/uploads/2023/06/Chemours-Teflon_FEP-Datasheet-cobranded-pf.pdf
    year: 2022
    kind: datasheet
    license: manufacturer bulletin, cited not reproduced
  usgs-mcs2026-silver:
    title: Mineral Commodity Summaries 2026, Silver
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  sds-silver-sam:
    title: 'Safety Data Sheet: Silver (Stanford Advanced Materials, brand SAM, version 3.0, revision 09/04/2017)'
    id: CAS 7440-22-4; revision 09/04/2017
    url: https://www.sputtertargets.net/wp-content/uploads/2018/05/Silver-Ag-sds.pdf
    year: 2017
    kind: datasheet
    license: supplier document, linked not reproduced
  wikipedia-fep:
    title: Fluorinated ethylene propylene (Wikipedia), used for monomers and composition only
    id: Wikipedia article, Fluorinated ethylene propylene
    url: https://en.wikipedia.org/wiki/Fluorinated_ethylene_propylene
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (Wikipedia)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 25
  unreachable: 1
  caveats: 3
  note: Written by an AI assistant on 2026-11-01 from pages read in this run. PubChem was blocked by a reCAPTCHA. Values are copied as printed; the Dunmore pair is not split into alpha and epsilon.
story:
  recipe:
    line: 'Silvered FEP is a laminate: a nominally 5 mil fluorinated ethylene propylene film with about 1600 Å of silver and about 400 Å of Inconel vapour-deposited on its back (NASA TM 104096). Silver reflects sunlight, the transparent film protects it, and a SiOx barrier coat sits on the FEP side in the test construction NASA called SiOx/FEP/Ag (NASA TM 106146).'
    parts:
      - name: Fluorinated ethylene propylene (FEP) film
        share: nominally 5 mil, Type A film (NASA TM 104096)
        role: Transparent outer layer. Sunlight passes through it and is reflected by the silver, which gives a low solar absorptance.
      - name: Silver
        symbol: Ag
        share: approximately 1600 Å, vapour-deposited (NASA TM 104096)
        role: Specular reflector behind the film.
      - name: Inconel
        share: approximately 400 Å, vapour-deposited (NASA TM 104096)
        role: Thin metal layer over the silver. Dunmore calls it a protective layer.
      - name: Silicon oxide (SiOx) barrier
        share: thickness not found
        role: Barrier to atomic oxygen on the FEP in the NASA test construction. Its thickness and whether vendor product uses it are not confirmed.
      - name: Pressure-sensitive adhesive
        share: Permacel P223 on the NASA test samples
        role: Bonds the laminate to the substrate. The adhesive on the vendor product is not stated.
  risk_groups:
    - title: For people
      level: 0
      verdict: Low hazard as a finished film; the bulk silver safety data…
      lead: The finished film has no safety data sheet read in this run. The bulk silver safety data sheet classifies silver as very toxic to aquatic life with long-lasting effects.
      points:
        - label: The silver metal
          line: The bulk silver sheet classifies silver as H400 and H410 (very toxic to aquatic life) and prints an oral LD50 in rat of more than 5,000 mg/kg. It prints an OSHA limit of 0.01 mg/m3 and an ACGIH limit of 0.1 mg/m3.
        - label: The FEP film
          line: The Chemours bulletin describes the polymer as chemically inert to virtually all chemicals. No hazard statement for the film was found in a page read in this run.
    - title: If the film is damaged in orbit
      lead: These results come from ground tests and one flight sample, not from incidents.
      points:
        - label: Atomic oxygen
          line: In NASA's plasma-asher test, the SiOx/FEP/Ag sample was removed at 1.1x10^22 atoms/cm2 after severe darkening. On LDEF, the most exposed film lost more than 0.001 inch of 0.005 inch.
        - label: Impacts
          line: NASA reports that FEP delaminated from the silver around impact sites on LDEF, and that exposed silicone adhesive can form a dark deposit on nearby surfaces.
    - title: Handling and storage
      points:
        - label: Storage of the silver metal
          line: The bulk silver sheet says the metal is air sensitive, so it should be stored under inert gas and kept dry. This does not describe the finished film.
        - label: Flammability of the film
          line: The bulletin rates the bare FEP film VTM-0 under UL 94, with an oxygen index of 95%.
  why: Silvered FEP Teflon is a flexible second-surface mirror. The silver sits behind a transparent fluoropolymer film, so the film faces space and the reflective metal is protected from the outside. The construction is used where a low solar absorptance and a high infrared emittance are both needed in a thin, bendable sheet. Vendor pages give a combined value of 0.13 to 0.16 for the outside surface, and NASA reports that the SiOx-coated version is damaged by atomic oxygen in low Earth orbit.
  uses:
    - where: Space Station Freedom radiators (candidate)
      line: NASA tested SiOx-coated silvered Teflon as a candidate coating for Space Station Freedom power-system radiators, along with two white paints and anodised aluminium. The test asked for a 30-year design life.
    - where: LDEF experiment trays
      line: NASA's analysis of LDEF material describes silvered FEP blankets that gave thermal protection to experiments on Tray F2 and Trays C5, C8 and A10 on the Long Duration Exposure Facility.
    - where: Spacecraft thermal blankets
      line: NASA describes the material as a flexible second-surface mirror thermal control coating used in a variety of space applications where thermal protection is a consideration.
  can_do:
    - label: Low solar absorptance to emittance
      value: 0.13 to 0.16 outside surface
      line: Dunmore prints a typical outside-surface value of 0.13 to 0.16 for the solar absorptance and emittance pair. The page does not split the two values, so this profile does not state either one alone.
    - label: Operating temperature
      value: '-185 to 125 °C (Dunmore)'
      line: Dunmore prints an operating range of -185 to 125 °C. SatCatalog prints -150 to 125 °C. Both are kept because the vendors do not agree on the lower limit.
    - label: Atomic-oxygen erosion
      value: more than 0.001 inch lost
      line: On LDEF, the most exposed film lost more than 0.001 inch of its 0.005 inch thickness in 5 years and 9 months, according to NASA's preliminary estimate.
    - label: Outgassing limits
      value: TML below 1.0%, CVCM below 0.1%
      line: SatCatalog quotes ASTM E-595 limits of TML below 1.0% and CVCM below 0.1%. These are qualification limits, not measured results for this product.
  compare: Silvered FEP trades atomic-oxygen tolerance for a low solar absorptance. In NASA's 1993 plasma-asher test, the SiOx/FEP/Ag sample was removed at 1.1x10^22 atoms/cm2 after severe degradation, while the white paints Z-93 and YB-71 and the anodised aluminium were carried through the full test fluence in the same asher test (the full value is printed in NASA TM 106146, Exposure in an RF Plasma Asher). The bare FEP film is rated for a continuous service range of -240 to 205 °C, but the silvered product's own published range is -185 to 125 °C (Dunmore) or -150 to 125 °C (SatCatalog).
  compare_rows:
    - label: Operating range, upper limit
      benchmark: max_service_temp
    - label: Melt point of the bare FEP film
      benchmark: melting_point
    - label: Density of the bare FEP film
      benchmark: density
  handling:
    - The bulk silver metal is classed as very toxic to aquatic life. Avoid releasing it to the environment.
    - Keep the silver metal under inert gas and dry. This does not describe the finished film.
    - The film is rated VTM-0 under UL 94 for the bare FEP at 1 mil.
  good_for:
    - Thin, flexible thermal control on spacecraft, where a low solar absorptance and a high emittance are both needed (Dunmore and NASA).
    - Use over a published operating range of -185 to 125 °C, according to Dunmore.
  watch_out:
    - Atomic oxygen in low Earth orbit erodes the FEP. On LDEF, the most exposed film lost more than 0.001 inch.
    - A SiOx barrier does not protect the FEP where thermal cycling has cracked it, according to NASA.
    - 'The two published operating ranges disagree on the lower limit: -185 °C (Dunmore) and -150 °C (SatCatalog).'
  verdict: Silvered FEP is a well-documented thermal-control film for the sunward side of a spacecraft. Its low solar absorptance is useful, but its atomic-oxygen tolerance depends on the barrier staying intact, and the published data do not settle the lower operating limit.