Sterling silver Ag 92.5 Cu 7.5
Ag 92.5, Cu 7.5 (by weight), a silver-copper alloy
Sterling silver is an alloy of 92.5% silver and 7.5% copper, the standard silver alloy for jewellery and silverware.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Conduct electricity
1.8 µOhmcm
Carry load
207 MPa
Expansion with heat
19 x10-6 K-1
Recipe, share of the weight
- Ag not statedSilver
- Cu not statedCopper
Best for
Silver-rich alloy that is harder than fine silver and still conducts electricity (supplier resistivity 1.8 µOhmcm, as-rolled disk)
Weakest at
Tarnishing in sulphur-bearing air and corrosion; no sterling-specific atomic-oxygen or tarnish rate was found in a source we could open
Risk at a glance
- People Low. Depends on form and supplier
- If it fails No data. No failure risks recorded
- Corrosion No data. No corrosion data recorded
Quick facts: Ag 92.5 Cu 7.5
| Property | Value | Basis |
|---|---|---|
| Density | 10.4 g/cm³ | 1 sourced value |
| Tensile strength | 207 MPa | 1 sourced value |
| Thermal expansion (CTE) | 19 ppm/K | 1 sourced value |
| Melting point | 788 to 891 °C | 1 sourced value |
| Specific heat | 245 J/(kg·K) | 1 sourced value |
| Electrical resistivity | 1.8e-8 Ω·m | 1 sourced value |
What is the density of Sterling silver?
Sterling silver has a density of 10.4 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Sterling silver?
Sterling silver has a coefficient of thermal expansion of 19 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Sterling silver?
Sterling silver has a melting point of 788 to 891 °C. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Sterling silver?
Sterling silver has a tensile strength of 207 MPa. The source and test conditions are listed in the properties table on this page.
What is Sterling silver used for?
Uses recorded in the sources include Silver-copper-lithium brazing alloy in the Skylab M-552 ethothermic brazing experiment (related braze, not sterling silver); Silver-copper front paste on a silicon heterojunction solar cell (related paste, not sterling silver).
Why it exists
Sterling silver is a copper-hardened silver alloy used in jewellery, silverware and as a conductor where a little strength is needed. The supplier data show a melting range of 788 to 891 degC and a resistivity of 1.8 µOhmcm for an as-rolled disk. Its density of 10.4 g/cm3 is is the figure printed for this disk. In a space context the alloy is not a known flight material in this record; the closest space links are silver-copper brazing and solar-cell paste, which are different compositions.
Where it's used
Brazing in space
A NASA Skylab experiment in 1974 used a silver-copper-lithium braze (71.8% Ag, 28% Cu, 0.2% Li) to join nickel parts in space. It is a related braze, not sterling silver.
Solar-cell paste
Fraunhofer ISE reports a silicon heterojunction cell with a silver-copper paste on the front and pure copper on the rear, at 1.4 milligrams of silver per watt peak. The composition of the silver-copper paste is not given in the release.
Recipe
Ag 92.5, Cu 7.5 (by weight), a silver-copper alloy
Sterling silver is a silver-copper alloy: 92.5% silver and 7.5% copper by weight. The silver is the base metal and the copper is added to harden it. The alloy is annealed at 650 degC for 30 minutes and quenched under N2+H2 protective gas, according to the Total Materia data sheet.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Silver Ag | not stated | The base metal. It gives the alloy its conduction and its silver colour. |
| Copper Cu | not stated | The hardening addition. It raises hardness and strength over fine silver; the ASM abstract notes copper lowers electrical and thermal conductivity. |
Weight shares are as printed in the sources.
What it can do
Conduct electricity
1.8 µOhmcm
measured
The supplier lists a resistivity of 1.8 µOhmcm for the as-rolled disk. Copper in the alloy raises the resistivity above that of pure silver.
Carry load
207 MPa
measured
The as-rolled disk has a tensile strength of 207 MPa and a Vickers hardness of 71.
Expansion with heat
19 x10-6 K-1
measured
The coefficient of thermal expansion is 19 (x10 to the power -6 per K) between 20 and 100 degC.
How it compares
No source in this record compares sterling silver with another metal under the same test, so no ranking is made. The alloy is harder than fine silver and is chosen where some strength is needed with silver's conduction. Its values are for a single supplier disk, so they should be checked against the supplier's form and temper.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | Ag 92.5 Cu 7.5 | Au | Ag | Pt | Pd | Rh | Ru | Os | Au alloys | AuSn | Ag alloys | Pd-Ag | Pd-Cu, Pd-Ni, Pd-Cr | Pt-Rh | Pt-Ir | Pt-W, Pt-Cu |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | ||||||||||||||||
| Melting range of sterling silver | 788 to 891 °C2 | 1065 °C | 961.9 °C | 1769 °C | 1555 °C | 1964 °C | 2334 °C | 3033 °C | 955 °C | 280 °C | 780 °C | no data | 1397 °C | 1840 to 1870 °C | 1790 to 1800 °C | 1865 to 1885 °C |
| Specific heat | 245 J K-1 kg-14 | 129.1 J/(kg K) | 237 J/(K kg) | 132.6 J/(kg·K) | no data | 242.7 J/(kg·K) | no data | 131 J/(kg·K) | no data | no data | no data | no data | no data | no data | no data | no data |
| Physical and electrical | ||||||||||||||||
| Density of a 0.5 mm as-rolled sterling disk | 10.4 g/cm³1 | 19.3 g/cm³ | 10.5 g/cm³ | 21.45 g/cm³ | 12.02 g/cm³ | 12.42 g/cm³ | 12.36 g/cm³ | 22.5 g/cm³ | 15.8 g/cm³ | 14.7 - | 10 Mg/m3 | 10.9 g/cm³ | 10.8 g/cm³ | 19.97 g/cm³ | 21.54 g/cm³ | 21.26 g/cm³ |
| Electrical resistivity of sterling silver | 1.8 µOhmcm3 | 2.2×10^-8 ohm m | 1.63 µΩ·cm | 10.6 µΩ·cm | 10.8 uOhm.cm | 43.3 nΩ·m | 71 nΩ·m | 8.8 µΩ·cm | 15.5 µΩ·cm | no data | 20.4 x10-9 ohm m | 15 uOhm.cm | no data | no data | no data | 62 to 68 µOhm cm |
| Vickers hardness | 71 kgf mm-27 | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data |
| Other measurements | ||||||||||||||||
| Coefficient of thermal expansion | 19 x10-6 K-15 | 14.2 ppm/K | 19.1 ppm/K | 8.93 ppm/K | 11.8 ppm/K | 8.46 ppm/K | 6.78 ppm/K | 4.57 ppm/K | 14 ppm/K | 16 ppm/°C | 19.6 x10-6 per °C | no data | no data | no data | no data | no data |
| Tensile strength, as rolled | 207 MPa6 | no data | no data | 150 MPa | no data | no data | no data | no data | 616 MPa | 275 MPa | 372 MPa | 310 MPa | no data | 300 to 680 MPa | 340 MPa | 800 to 1100 MPa |
Why choose it, and why not
Good for
- Conduction with some strength. Resistivity 1.8 µOhmcm and tensile strength 207 MPa as rolled.
- Hardness over fine silver. The copper addition gives a Vickers hardness of 71 in the as-rolled disk.
Watch out for
- Tarnish. The copper in the alloy changes how the surface tarnishes; no sourced rate is in this file.
- Space data. No sterling-specific atomic-oxygen, outgassing or thermal-vacuum record was found.
- Form and hazard. Hazard classification depends on form, so check the supplier safety data sheet.
Sterling silver is a practical silver alloy when some strength is needed alongside conduction. For space use, the file has no sterling-specific test record, so any flight use needs its own data.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density of a 0.5 mm as-rolled sterling disk | Value printed in the physical properties table of the supplier page | form 0.5 mm disk, as rolledtemperature not stated on the page | Total Materia prints 10.4 kg/dm3 for 0 to 30 degC for the same composition. |
| 2 | Melting range of sterling silver | Range printed in the thermal properties table of the supplier page | form 0.5 mm disk, as rolled | Total Materia prints 820 to 890 degC with no stated condition; that wider-looking range is not used here. |
| 3 | Electrical resistivity of sterling silver | Value printed in the electrical properties table of the supplier page; the temperature coefficient cell is blank | form 0.5 mm disk, as rolledtemperature not stated on the page | — |
| 4 | Specific heat | Printed as 245 at 23 degC in the thermal properties table | temperature 23 °Cform 0.5 mm disk, as rolled | — |
| 5 | Coefficient of thermal expansion | Printed as 19 (x10 to the power -6 per K) in the thermal properties table | temperature range 20 to 100 °Cform 0.5 mm disk, as rolled | — |
| 6 | Tensile strength, as rolled | Printed in the mechanical properties table of the supplier page; the test standard and temperature are not stated | temper as rolledform 0.5 mm disk | Only the as-rolled figure is entered. Total Materia gives a 280 to 550 MPa range with no temper stated, and that range is not used because it mixes tempers. |
| 7 | Vickers hardness | Printed in the mechanical properties table of the supplier page | temper as rolledform 0.5 mm disk | — |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The alloy itself has no GHS classification in a record we could read. The elements it is made of carry hazard codes in PubChem, and the classification varies by form.
- Silver
- PubChem's silver record lists suspected reproductive and organ toxicity codes, and aquatic toxicity codes. 28.9% of company reports say silver does not meet GHS hazard criteria.
- Copper
- PubChem's copper record lists aquatic toxicity codes and H302 (harmful if swallowed, 21.7%). 52.5% of reports say copper does not meet GHS hazard criteria.
If it fails
No failure record for sterling silver was read in this run, so this group is left as a gap.
- Gap
- The space links in this file are for a silver-copper-lithium braze and a silver-copper solar paste, not for a sterling part flown in orbit.
Handling and storage
- Safety data sheet
- Check the supplier safety data sheet for the alloy and form you buy, since PubChem's classification depends on the notifier.
Test details
The original wording and numbers from the sources, for readers who want them.
Handling and storage
- The PubChem silver record says that 28.9% of reports find silver does not meet GHS hazard criteria, so check the supplier safety data sheet for the alloy and form you buy. No safety data sheet for sterling silver itself was read in this run.
Supply and geography
How common the raw materials are and where they come from.
Silver
USGS: silver is primarily obtained as a byproduct from lead-zinc, copper and gold mines; polymetallic deposits account for more than two-thirds of US and world resources. World mine production 25,300 t in 2024 and an estimated 26,000 t in 2025.
- Top producers (2025)
- Mexico 24.2%, Peru 13.8%, China 13.1%, Bolivia 5.8%, Chile 5.4%
- Critical mineral lists
- US: listed
- Recycling
- USGS: about 1,000 tons of silver was recovered from new and old scrap in 2025, about 11% of US apparent consumption.
- Substitutes
- USGS: aluminium and rhodium may replace silver in mirrors and reflecting surfaces; stainless steel and other metals replace silver in some surgical and tableware uses.
Copper
- Top producers (2025)
- Chile 23%, Congo (Kinshasa) 13.9%, Peru 11.7%, China 7.8%, United States 4.3%
- Critical mineral lists
- US: listed
- Recycling
- USGS: old scrap and new scrap provided about 160,000 t and 760,000 t of copper in 2025; brass and wire-rod mills accounted for about 80% of copper recovered from scrap.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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spore: profile
id: sterling-silver
spore_version: 0.2
family: precious-metals
name: Sterling silver
abbreviation: Ag 92.5 Cu 7.5
role: conductor / jewellery and joining alloy
category: metals
type: precious-metals
summary: |
Sterling silver is an alloy of 92.5% silver and 7.5% copper, the standard silver alloy for jewellery and silverware. The copper makes it harder and stronger than fine silver, at some cost in electrical conduction. A supplier data sheet for a 0.5 mm as-rolled disk gives a density of 10.4 g/cm3, a melting range of 788 to 891 degC and an electrical resistivity of 1.8 microohm cm. Spacecraft data for this exact alloy were not found in this run, so the space links in this file come from silver-copper brazing and solar-cell paste.
best_for: Silver-rich alloy that is harder than fine silver and still conducts electricity (supplier resistivity 1.8 µOhmcm, as-rolled disk)
weakest_at: Tarnishing in sulphur-bearing air and corrosion; no sterling-specific atomic-oxygen or tarnish rate was found in a source we could open
identity:
formula: Ag 92.5, Cu 7.5 (by weight), a silver-copper alloy
composition: Ag 92.5 wt%, Cu 7.5 wt%
anneal: Annealed 650 degC for 30 min, then quenched under N2+H2 protective gas (Total Materia data sheet)
source: goodfellow-sterling
where: 'Properties common to all products in this list: composition "Ag 92.5/Cu 7.5"; Total Materia composition "Ag 92.500%, Cu 7.500%" and heat-treatment line'
tags:
environments: []
stresses: []
applications:
- in-space-manufacturing
- solar-arrays
properties:
- benchmark: density
label: Density of a 0.5 mm as-rolled sterling disk
value: 10.4
unit: g/cm3
scope: material
conditions:
form: 0.5 mm disk, as rolled
temperature: not stated on the page
method: Value printed in the physical properties table of the supplier page
status: ground
note: Total Materia prints 10.4 kg/dm3 for 0 to 30 degC for the same composition.
source: goodfellow-sterling
where: Physical Properties table
- benchmark: melting_point
label: Melting range of sterling silver
value: 788
value_high: 891
bound: range
unit: degC
scope: material
conditions:
form: 0.5 mm disk, as rolled
method: Range printed in the thermal properties table of the supplier page
status: ground
note: Total Materia prints 820 to 890 degC with no stated condition; that wider-looking range is not used here.
source: goodfellow-sterling
where: Thermal Properties table
- benchmark: electrical_resistivity
label: Electrical resistivity of sterling silver
value: 1.8
unit: µOhmcm
scope: material
conditions:
form: 0.5 mm disk, as rolled
temperature: not stated on the page
method: Value printed in the electrical properties table of the supplier page; the temperature coefficient cell is blank
status: ground
source: goodfellow-sterling
where: Electrical Properties table
- benchmark: specific_heat
label: Specific heat
value: 245
unit: J K-1 kg-1
scope: material
conditions:
temperature: 23 degC
form: 0.5 mm disk, as rolled
method: Printed as 245 at 23 degC in the thermal properties table
status: ground
source: goodfellow-sterling
where: Thermal Properties table
- benchmark: cte
label: Coefficient of thermal expansion
value: 19
unit: x10-6 K-1
scope: material
conditions:
temperature_range: 20 to 100 degC
form: 0.5 mm disk, as rolled
method: Printed as 19 (x10 to the power -6 per K) in the thermal properties table
status: ground
source: goodfellow-sterling
where: Thermal Properties table
- benchmark: ultimate_tensile_strength
label: Tensile strength, as rolled
value: 207
unit: MPa
scope: material
conditions:
temper: as rolled
form: 0.5 mm disk
method: Printed in the mechanical properties table of the supplier page; the test standard and temperature are not stated
status: ground
note: Only the as-rolled figure is entered. Total Materia gives a 280 to 550 MPa range with no temper stated, and that range is not used because it mixes tempers.
source: goodfellow-sterling
where: Mechanical Properties table
- benchmark: hardness_vickers
label: Vickers hardness
value: 71
unit: kgf mm-2
scope: material
conditions:
temper: as rolled
form: 0.5 mm disk
method: Printed in the mechanical properties table of the supplier page
status: ground
source: goodfellow-sterling
where: Mechanical Properties table
corrosion: []
risks:
hazards:
- text: PubChem silver record (CID 23954) lists H361f (suspected of damaging fertility), H373 (may cause damage to organs through prolonged or repeated exposure), H400 (very toxic to aquatic life) and H410 (very toxic to aquatic life with long-lasting effects). The record notes that 28.9% (623 of 2154) of reports say silver does not meet GHS hazard criteria.
ghs:
- H361f
- H373
- H400
- H410
source: pubchem-silver
where: GHS Hazard Statements and Note in the GHS Classification section
- text: PubChem copper record (CID 23978) lists H400 and H410 and H302 (21.7%, harmful if swallowed). The record notes that copper does not meet GHS hazard criteria for 52.5% (1818 of 3463) of reports.
ghs:
- H302
- H400
- H410
source: pubchem-copper
where: GHS Hazard Statements and Note in the GHS Classification section
failure_risks: []
side_effects: []
handling:
- text: The PubChem silver record says that 28.9% of reports find silver does not meet GHS hazard criteria, so check the supplier safety data sheet for the alloy and form you buy. No safety data sheet for sterling silver itself was read in this run.
source: pubchem-silver
where: Note in the GHS Classification section
mitigations: []
uses:
- application: in-space-manufacturing
device: Silver-copper-lithium brazing alloy in the Skylab M-552 ethothermic brazing experiment (related braze, not sterling silver)
example: NASA's Skylab M-552 brazed a nickel ferrule to a nickel tube with Lithobraze BT, a braze of 71.8% Ag, 28% Cu and 0.2% Li, in a space environment near zero gravity. The source is a 1974 NASA report on the tracer study of the braze flow.
source: skylab-m552
where: Abstract and body text, NTRS 19750002891
- application: solar-arrays
device: Silver-copper front paste on a silicon heterojunction solar cell (related paste, not sterling silver)
example: Fraunhofer ISE reports a silicon heterojunction cell with a silver-copper paste on the front and pure copper paste on the rear, with a total silver consumption of 1.4 milligrams per watt peak. The release does not give the composition of the silver-copper paste.
source: fraunhofer2025
where: Press release of 28 April 2025, introductory summary and quotation
supply:
- subject: Silver
abundance: 'USGS: silver is primarily obtained as a byproduct from lead-zinc, copper and gold mines; polymetallic deposits account for more than two-thirds of US and world resources. World mine production 25,300 t in 2024 and an estimated 26,000 t in 2025.'
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 Final 2025 List of Critical Minerals (silver added; 90 FR 50494, 7 November 2025)
listed: true
recycling: 'USGS: about 1,000 tons of silver was recovered from new and old scrap in 2025, about 11% of US apparent consumption.'
substitutes:
- 'USGS: aluminium and rhodium may replace silver in mirrors and reflecting surfaces; stainless steel and other metals replace silver in some surgical and tableware uses.'
source: usgs-mcs2026-silver
where: Mineral Commodity Summaries 2026, Silver chapter, World Mine Production and Reserves table (2025e); shares calculated by Space Mushroom from the 26,000 t total; Recycling; Substitutes
- subject: Copper
producers:
- country: Chile
share_percent: 23
year: 2025
- country: Congo (Kinshasa)
share_percent: 13.9
year: 2025
- country: Peru
share_percent: 11.7
year: 2025
- country: China
share_percent: 7.8
year: 2025
- country: United States
share_percent: 4.3
year: 2025
critical_lists:
- list: USGS Final 2025 List of Critical Minerals (copper added, 90 FR 50494, 7 November 2025)
listed: true
recycling: 'USGS: old scrap and new scrap provided about 160,000 t and 760,000 t of copper in 2025; brass and wire-rod mills accounted for about 80% of copper recovered from scrap.'
substitutes: []
source: usgs-mcs2026-copper
where: Mineral Commodity Summaries 2026, Copper chapter, World Mine and Refinery Production table (2025e, 23,000 kt world total); shares calculated by Space Mushroom; Critical Minerals and Recycling paragraphs
media: []
documents:
- title: Goodfellow sterling silver disk (Ag92.5-Cu7.5) properties page
type: datasheet
url: https://www.goodfellow.com/usa/sterling-silver-disc-ag92-5-cu7-5-group
year: 2025
- title: 'Total Materia: Ag 925 Cu (PX Group SA product data sheet)'
type: database
url: https://www.totalmateria.com/en-us/material/3308698
year: 2026
- title: 'ASM Alloy Digest Ag-11: Sterling Silver, Silver-Copper Alloy (abstract only; full text paywalled)'
type: database
url: https://dl.asminternational.org/alloy-digest/article/34/2/Ag-11/4889/STERLING-SILVERSilver-Copper-Alloy
year: 1972
- title: 'USGS Mineral Commodity Summaries 2026: Silver'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Copper'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
year: 2026
- title: 'PubChem: Silver (CID 23954), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/Silver
year: 2026
- title: 'PubChem: Copper (CID 23978), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/Copper
year: 2026
- title: 'NASA NTRS 19750002891: Radioisotope tracer studies in the NASA Skylab ethothermic brazing experiment M-552'
type: report
url: https://ntrs.nasa.gov/citations/19750002891
year: 1974
- title: 'Fraunhofer ISE press release: silicon heterojunction solar cells with record savings in silver (28 April 2025)'
type: report
url: https://www.ise.fraunhofer.de/en/press-media/news/2025/silicon-heterojunction-solar-cells-realized-with-record-savings-in-silver.html
year: 2025
gaps:
- Elongation at break for the as-rolled disk was printed as less than 41% in the Goodfellow table when read through the rendered page, but that figure is not in the page's static HTML, so it was removed rather than left unverified.
- No thermal conductivity for the 92.5/7.5 alloy was found in a readable source. The Goodfellow page prints none, Total Materia prints none, and the Shapeways data sheet returned HTTP 404 in this run.
- No elastic modulus for sterling silver was read. The silver profile's 82.7 GPa is for pure silver and is not used here.
- The Total Materia yield strength (150 to 500 MPa), tensile range (280 to 550 MPa) and elongation range (5 to 60%) give no temper, so they are not entered. Total Materia's figures for density and melting range are not used because the Goodfellow figures are for a stated form.
- The ASM Alloy Digest Ag-11 full text is paywalled. Only its abstract was read, which gives the minimum silver content of 92.50% for silversmiths' grade. Its physical, tensile and corrosion data were not seen.
- 'Tarnish and corrosion: a 2015 Heritage Science paper on sulphidation of sterling silver (Storme et al., DOI 10.1186/s40494-015-0054-1) was found by search, but the full text redirected to a publisher login page. No sterling tarnish rate, sulphur test or atomic-oxygen result was entered.'
- 'No space-environment data for sterling silver itself were found: no atomic-oxygen erosion, outgassing, thermal-vacuum, radiation or cryogenic result.'
- Brazing alloy composition for BAg-8 (Ag 72, Cu 28, eutectic near 780 degC) was not confirmed in a readable source. The Lucas-Milhaupt Silvaloy 721 page returned HTTP 404 and the MakeItFrom BAg-8 page returned HTTP 403. No AWS A5.8 designation is listed in this file.
- 'Coin silver (90% Ag) was not covered: no source was read for its composition or properties.'
- No UNS, EN, DIN, JIS or ASTM designation for sterling silver was read from a page that prints it, so identity.designations is empty.
- Electrical conductivity in percent IACS was not read in this run, so it is not entered.
- The hazard data are for elemental silver and copper, not a sterling-silver safety data sheet. The PubChem Silver record does not separate the massive, powder and nano forms in the text read in this run.
- Failure modes (for example brazed-joint failure, solder fatigue or silver-copper mixed-tempering effects) were not sourced, so failure_risks is empty.
- The copper EU critical raw materials list status and copper abundance were not checked in this run.
sources:
goodfellow-sterling:
title: Sterling silver disk (Ag92.5-Cu7.5), material properties (Goodfellow)
id: Goodfellow Ag92.5-Cu7.5 disk, as-rolled, 0.5 mm
url: https://www.goodfellow.com/usa/sterling-silver-disc-ag92-5-cu7-5-group
year: 2025
kind: datasheet
license: supplier web page, cited not reproduced
asm-ag11:
title: 'STERLING SILVER: Silver-Copper Alloy (ASM Alloy Digest Ag-11), abstract'
id: ASM Alloy Digest, Ag-11, vol. 34 issue 2 (abstract read; full text paywalled)
url: https://dl.asminternational.org/alloy-digest/article/34/2/Ag-11/4889/STERLING-SILVERSilver-Copper-Alloy
year: 1972
kind: handbook
license: ASM International, abstract cited only
totalmateria-ag925:
title: Ag 925 Cu (PX Group SA product data sheet), Total Materia
id: Total Materia material 3308698
url: https://www.totalmateria.com/en-us/material/3308698
year: 2026
kind: database
license: database page, cited not reproduced
usgs-mcs2026-silver:
title: 'Mineral Commodity Summaries 2026: Silver'
id: U.S. Geological Survey, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mcs2026-copper:
title: 'Mineral Commodity Summaries 2026: Copper'
id: U.S. Geological Survey, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
year: 2026
kind: report
license: public domain (USGS)
pubchem-silver:
title: 'PubChem compound record: Silver (CID 23954)'
id: CID 23954; CAS 7440-22-4
url: https://pubchem.ncbi.nlm.nih.gov/compound/Silver
year: 2026
kind: database
license: public domain (NCBI)
pubchem-copper:
title: 'PubChem compound record: Copper (CID 23978)'
id: CID 23978
url: https://pubchem.ncbi.nlm.nih.gov/compound/Copper
year: 2026
kind: database
license: public domain (NCBI)
skylab-m552:
title: Radioisotope tracer studies in the NASA Skylab ethothermic brazing experiment M-552
id: NTRS 19750002891
url: https://ntrs.nasa.gov/citations/19750002891
year: 1974
kind: report
license: public domain (NASA)
fraunhofer2025:
title: Silicon Heterojunction Solar Cells Realized with Record Savings in Silver (press release)
id: Fraunhofer ISE, 28 April 2025
url: https://www.ise.fraunhofer.de/en/press-media/news/2025/silicon-heterojunction-solar-cells-realized-with-record-savings-in-silver.html
year: 2025
kind: web
license: press release, cited not reproduced
wikipedia-sterling:
title: Sterling silver (Wikipedia), composition and history only
id: Lead section, composition
url: https://en.wikipedia.org/wiki/Sterling_silver
year: 2026
kind: web
license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 7
unreachable: 4
caveats: 4
note: 'Written by an AI assistant on 2026-10-26. Goodfellow values were read from the page''s table in this run. Total Materia composition and anneal condition were read from its page; its ranges were not used because they mix tempers or give no condition. Unreachable in this run: Shapeways data sheet (404), Lucas-Milhaupt Silvaloy 721 page (404), MakeItFrom BAg-8 page (403), Storme et al. full text (publisher login). ASM Ag-11 full text is paywalled. Caveats: the alloy is single-sourced for properties; copper producer shares are calculated; the space links are for related alloys, not sterling.'
story:
recipe:
line: 'Sterling silver is a silver-copper alloy: 92.5% silver and 7.5% copper by weight. The silver is the base metal and the copper is added to harden it. The alloy is annealed at 650 degC for 30 minutes and quenched under N2+H2 protective gas, according to the Total Materia data sheet.'
parts:
- name: Silver
symbol: Ag
share: 92.5 wt%
role: The base metal. It gives the alloy its conduction and its silver colour.
- name: Copper
symbol: Cu
share: 7.5 wt%
role: The hardening addition. It raises hardness and strength over fine silver; the ASM abstract notes copper lowers electrical and thermal conductivity.
risk_groups:
- title: For people
level: 1
verdict: Depends on form and supplier
lead: The alloy itself has no GHS classification in a record we could read. The elements it is made of carry hazard codes in PubChem, and the classification varies by form.
points:
- label: Silver
line: PubChem's silver record lists suspected reproductive and organ toxicity codes, and aquatic toxicity codes. 28.9% of company reports say silver does not meet GHS hazard criteria.
- label: Copper
line: PubChem's copper record lists aquatic toxicity codes and H302 (harmful if swallowed, 21.7%). 52.5% of reports say copper does not meet GHS hazard criteria.
- title: If it fails
lead: No failure record for sterling silver was read in this run, so this group is left as a gap.
points:
- label: Gap
line: The space links in this file are for a silver-copper-lithium braze and a silver-copper solar paste, not for a sterling part flown in orbit.
- title: Handling and storage
points:
- label: Safety data sheet
line: Check the supplier safety data sheet for the alloy and form you buy, since PubChem's classification depends on the notifier.
why: Sterling silver is a copper-hardened silver alloy used in jewellery, silverware and as a conductor where a little strength is needed. The supplier data show a melting range of 788 to 891 degC and a resistivity of 1.8 µOhmcm for an as-rolled disk. Its density of 10.4 g/cm3 is is the figure printed for this disk. In a space context the alloy is not a known flight material in this record; the closest space links are silver-copper brazing and solar-cell paste, which are different compositions.
uses:
- where: Brazing in space
line: A NASA Skylab experiment in 1974 used a silver-copper-lithium braze (71.8% Ag, 28% Cu, 0.2% Li) to join nickel parts in space. It is a related braze, not sterling silver.
- where: Solar-cell paste
line: Fraunhofer ISE reports a silicon heterojunction cell with a silver-copper paste on the front and pure copper on the rear, at 1.4 milligrams of silver per watt peak. The composition of the silver-copper paste is not given in the release.
can_do:
- label: Conduct electricity
benchmark: electrical_resistivity
line: The supplier lists a resistivity of 1.8 µOhmcm for the as-rolled disk. Copper in the alloy raises the resistivity above that of pure silver.
- label: Carry load
benchmark: ultimate_tensile_strength
line: The as-rolled disk has a tensile strength of 207 MPa and a Vickers hardness of 71.
- label: Expansion with heat
benchmark: cte
line: The coefficient of thermal expansion is 19 (x10 to the power -6 per K) between 20 and 100 degC.
compare: No source in this record compares sterling silver with another metal under the same test, so no ranking is made. The alloy is harder than fine silver and is chosen where some strength is needed with silver's conduction. Its values are for a single supplier disk, so they should be checked against the supplier's form and temper.
compare_rows:
- label: Density
benchmark: density
- label: Melting range
benchmark: melting_point
- label: Electrical resistivity
benchmark: electrical_resistivity
handling:
- Check the supplier safety data sheet for the alloy and form. PubChem's silver and copper records classify differently by form.
- Annealing is done at 650 degC for 30 minutes and then quenched under protective gas, per the Total Materia data sheet.
- Sulphur-bearing air tarnishes silver, and no sterling-specific tarnish rate is in this file.
good_for:
- Conduction with some strength. Resistivity 1.8 µOhmcm and tensile strength 207 MPa as rolled.
- Hardness over fine silver. The copper addition gives a Vickers hardness of 71 in the as-rolled disk.
watch_out:
- Tarnish. The copper in the alloy changes how the surface tarnishes; no sourced rate is in this file.
- Space data. No sterling-specific atomic-oxygen, outgassing or thermal-vacuum record was found.
- Form and hazard. Hazard classification depends on form, so check the supplier safety data sheet.
verdict: Sterling silver is a practical silver alloy when some strength is needed alongside conduction. For space use, the file has no sterling-specific test record, so any flight use needs its own data.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Sterling silver disk (Ag92.5-Cu7.5), material properties (Goodfellow) | datasheet | 2025 | 8 values | |
| STERLING SILVER: Silver-Copper Alloy (ASM Alloy Digest Ag-11), abstract | handbook | 1972 | 0 values | |
| Ag 925 Cu (PX Group SA product data sheet), Total Materia | database | 2026 | 0 values | |
| Mineral Commodity Summaries 2026: Silver | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026: Copper | report | 2026 | 1 value | |
| PubChem compound record: Silver (CID 23954) | database | 2026 | 2 values | |
| PubChem compound record: Copper (CID 23978) | database | 2026 | 1 value | |
| Radioisotope tracer studies in the NASA Skylab ethothermic brazing experiment M-552 | report | 1974 | 1 value | |
| Silicon Heterojunction Solar Cells Realized with Record Savings in Silver (press release) | web | 2025 | 1 value | |
| Sterling silver (Wikipedia), composition and history only | web | 2026 | 0 values |