Precious Metal Britannia Silver (958)
BS 958 Silver
Britannia Silver (958) is the historic English silver standard at 95.8% Ag, softer and more tarnish-resistant than sterling and traditionally hallmarked with the figure of Britannia.
Reference datasheet — Britannia Silver (958) is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the O condition
Britannia Silver (958) tempers and conditions
Britannia Silver (958) is supplied in 6 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ODefault Annealed | Standard stocked condition for raising, chasing, spinning and deep forming. | 60 | 240 | 48 | 47 HB | 92 % IACS |
As fabricated | Choose for cast holloware, hallmarked giftware and one-off sculptural pieces. | 85 | 215 | 22 | 52 HB | 90 % IACS |
Quarter hard | Pick when the part must keep shape during light forming but still bend without cracking. | 200 | 290 | 25 | 66 HB | 91 % IACS |
Half hard | General-purpose stiffened sheet/wire for bezels, settings and flatware blanks. | 260 | 330 | 12 | 85 HB | 90 % IACS |
Full hard | Maximum strength/wear for rims, hinges, clasps and thin structural sections. | 320 | 380 | 5 | 102 HB | 89 % IACS |
Extra hard | For springy wire, pin stems and clasp tongues where deflection recovery matters. | 370 | 420 | 3 | 114 HB | 88 % IACS |
What is Britannia Silver (958)?
Britannia Silver (958) is the historic English silver standard at 95.8% Ag, softer and more tarnish-resistant than sterling and traditionally hallmarked with the figure of Britannia. Its formability rating of 98 and 48% elongation make it the choice for hand-raised and spun hollowware, and it is stocked annealed (O), in H01 to H06 tempers and as-fabricated (F). Typical values are 60 MPa yield, 240 MPa tensile, 47 HB, 92% IACS and service to 200 °C. The low yield strength means finished pieces dent more readily than sterling 925, which remains the alternative where stiffness and wear matter. Britannia Silver (958) has a density of 10.41 g/cm³ (0.376 lb/in³), heavier than 52% of precious metal grades. It melts at 779°C (1,434 °F). Britannia Silver (958) has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 93% of precious metal grades. Elongation at break is 48% and the elastic modulus is 76 GPa (11 Msi).
What is Britannia Silver (958) used for?
- fine hollowware
- hallmarked flatware
- ecclesiastical silverware
- high-end jewelry
Advantages
- Ductile — tolerates forming and impact — 48%, better than 100% of precious metal grades
- Conducts heat well — 385 W/m·K (222.4 BTU/hr·ft·°F), better than 97% of precious metal grades
- Forms and bends easily — 98/100, better than 97% of precious metal grades
- High electrical conductivity — 92 % IACS, better than 96% of precious metal grades
- Polishes to a fine finish — 97/100, better than 96% of precious metal grades
Limitations
- Low stiffness — 76 GPa (11 Msi), worse than 96% of precious metal grades
- Low strength — 60 MPa (8.7 ksi), worse than 93% of precious metal grades
- Limited service temperature — 200°C (392 °F), worse than 89% of precious metal grades
Britannia Silver (958) properties
Typical room-temperature values for Britannia Silver (958)-O; bars are the position among precious metal grades.
Physical3
Britannia Silver (958) has a density of 10.41 g/cm³ (0.376 lb/in³), heavier than 52% of precious metal grades. It melts at 779°C (1,434 °F).
Mechanical11
Britannia Silver (958) has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 93% of precious metal grades. Elongation at break is 48% and the elastic modulus is 76 GPa (11 Msi).
Thermal6
Britannia Silver (958) is rated for continuous service to 200°C (392 °F). It conducts heat at 385 W/m·K (222.4 BTU/hr·ft·°F), better than 97% of precious metal grades. Thermal expansion is 19 µm/m·K (10.6 µin/in·°F).
Electrical3
Britannia Silver (958) conducts electricity at 92 % IACS, better than 96% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 56% of precious metal grades.
Sustainability4
Producing a kilogram of Britannia Silver (958) takes about 1,500 MJ of energy and emits 105 kg of CO₂ — more than 51% of precious metal grades. Typical recycled content is 55%.
Manufacturability8
Britannia Silver (958)'s machinability is fair (45/100, better than 59% of precious metal grades); weldability very good (70/100); formability excellent (98/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the precious metal family
Yield strength against density for every precious metal grade FabDigit runs. Britannia Silver (958) is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Britannia Silver (958)
Is Britannia Silver (958) easy to machine?
Very gummy — use sharp polished HSS or uncoated carbide, high rake, high speed, light feed with oil mist; collect all swarf for refining.
Can Britannia Silver (958) be welded?
Laser/PUK spot welding is the norm; the high thermal conductivity makes TIG difficult, and hard silver solders (Ag-Cu-Zn, 700–800 °C) are preferred for joining.
Can Britannia Silver (958) be formed, bent or molded?
Outstanding cold formability when annealed (raising, spinning, die-forming); anneal at 600–650 °C and quench between ~50% reduction steps, and avoid overheating past 780 °C (eutectic incipient melting).
Britannia Silver (958) chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Ag958 parts per thousand minimum fineness (UK Britannia standard / ISO 9202) | 95.84 – 96.5 | 95.9 |
| Znoptional deoxidiser in some casting grades | ≤ 0.3 | |
| Geused in some proprietary firescale-free 958 alloys | ≤ 0.5 | |
| Sioptional deoxidiser | ≤ 0.05 | |
| Pbimpurity limit; causes hot shortness | ≤ 0.01 | |
| Cuprincipal hardener | ≥ 3.3 (balance) |
What surface finishes work on Britannia Silver (958)?
Polishes to a mirror easily; less firescale than sterling but still requires pickling or protective flux; commonly rhodium-plated, lacquered or deliberately patinated with liver of sulfur.
Equivalent designations
Standards and trade names that resolve to Precious Metal Britannia Silver (958) in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- BS
- 958 Silver
- Also called
- Britannia Silver
How much does Britannia Silver (958) cost?
Britannia Silver (958) is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Britannia Silver (958) — frequently asked
What is Britannia Silver (958) used for?
Britannia Silver (958) is typically used for fine hollowware, hallmarked flatware, ecclesiastical silverware and high-end jewelry. In short: softest formable silver standard; more tarnish-resistant than sterling; near-pure silver conductivity.
What is the yield strength of Britannia Silver (958)?
Britannia Silver (958) has a typical yield strength of 60 MPa (8.7 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 93% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is Britannia Silver (958) easy to machine?
Reasonably — machinability is rated fair (45/100, better than 59% of precious metal grades). Very gummy — use sharp polished HSS or uncoated carbide, high rake, high speed, light feed with oil mist; collect all swarf for refining.
Can Britannia Silver (958) be welded?
Yes — weldability is rated very good (70/100). Laser/PUK spot welding is the norm; the high thermal conductivity makes TIG difficult, and hard silver solders (Ag-Cu-Zn, 700–800 °C) are preferred for joining.
What surface finishes work on Britannia Silver (958)?
Polishes to a mirror easily; less firescale than sterling but still requires pickling or protective flux; commonly rhodium-plated, lacquered or deliberately patinated with liver of sulfur.
Can Britannia Silver (958) be formed, bent or molded?
Outstanding cold formability when annealed (raising, spinning, die-forming); anneal at 600–650 °C and quench between ~50% reduction steps, and avoid overheating past 780 °C (eutectic incipient melting).
What is the maximum service temperature of Britannia Silver (958)?
Britannia Silver (958) is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Britannia Silver (958)-O and Britannia Silver (958)-H06?
O is the default condition — standard stocked condition for raising, chasing, spinning and deep forming. H06: for springy wire, pin stems and clasp tongues where deflection recovery matters. Yield strength is 60 MPa in O versus 370 MPa in H06.
How much does Britannia Silver (958) cost?
Britannia Silver (958) is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ISO 9202 Jewellery — Fineness of precious metal alloys — ISO (2019)
- Hallmarking Act 1973 (Britannia standard 958) — UK Assay Offices / British Hallmarking Council (1973)
- ASM Specialty Handbook: Precious Metals & Their Alloys / ASM Handbook Vol.2 — ASM International (1990)
- ASM Handbook Vol.3: Alloy Phase Diagrams (Ag-Cu system) — ASM International (1992)
- Santa Fe Symposium on Jewelry Manufacturing Technology — silver alloy property compilations — Met-Chem Research (2018)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.