VERIFIED(Source-Verified)

Britannia Silver 958

Primary Designation:UK-HALLMARK 958

Aliases:

Britannia Silver958 SilverAg958

Mat Grades internal verification confirms source-backed fidelity and data integrity. It does not constitute external certification or guaranteed lot conformity. Read engineering disclaimer →

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Data Completeness:2 composition elements and 13 condition-specific property values cataloged.

Omitted fields represent unverified properties. "Missing is better than invented."

Key Engineering Properties

Representative source rows, qualified by their reported conditions. Inspect the tables below for all values, limits, and source notes.

Density

10.4 g/cm³TYPICAL · at 20 °C

Electrical Conductivity

92 % IACSTYPICAL · at 20 °C

Thermal Conductivity

420 W/(m·K)TYPICAL · at 20 °C

Melting Point

undefined °C

Composition Excerpt

Ag ≥ 95.84 wt%Silver (min)

Standard Elemental Basis: MIN

Tensile Strength

≥ 185 MPaTYPICAL · Annealed (Soft) · temperature not stated

Engineering Summary

Britannia Silver 958 is a standardized silver-copper alloy comprising at least 95.84% pure silver (hallmarked as 958 parts per thousand), with the remainder typically copper. Introduced into English law by the Hallmarking Act of 1697 to prevent the melting of coinage, Britannia silver delivers greater ductility and malleability than sterling silver, making it well-suited to complex cold spinning, repoussé, and high-conductivity contact rivets.

Britannia Silver 958 Documented Applications

›Cold-spun metal vessels and complex holloware
›High-purity electrical contact rivets and instrument terminals
›Vitreous enamelling substrate components requiring elevated malleability
›Historical commemorative presentation items and coinage

Recognized Aliases

Source-backed commercial trade name and short designations cataloged in canonical data.

Britannia Silver958 SilverAg958

Britannia Silver 958 Specifications & Designations

Standard Designations & Applicable Specifications — Semantically classified designations distinguishing primary standard identifiers, commercial trade names, and applicable specification references.

Direct Standard DesignationsDIRECT DESIGNATION

4 Primary Identifiers

Scroll horizontally for full designation data

System	Identifier	Standard System Name	Classification Notes & Provenance
UK-HALLMARKPRIMARY	958	UK Hallmarking Act Fineness Mark	—Ref: Standard Specifications for Silver & Silver Alloys (ASTM B742, ASTM B413, ISO 9202, DIN 17510)
ISO	Ag958	International Organization for Standardization	—Ref: Standard Specifications for Silver & Silver Alloys (ASTM B742, ASTM B413, ISO 9202, DIN 17510)
DIN	Ag958	Deutsches Institut für Normung	—Ref: Standard Specifications for Silver & Silver Alloys (ASTM B742, ASTM B413, ISO 9202, DIN 17510)
EN	AgCu4.2	European Norm	—Ref: Standard Specifications for Silver & Silver Alloys (ASTM B742, ASTM B413, ISO 9202, DIN 17510)

Recognized Commercial Aliases & Trade NamesCOMMON ALIAS

3 Listed

Scroll horizontally for full alias classifications

Recognized Name / Alias	Classification	Technical Usage & Context
Britannia Silver	Commercial Alias	Colloquial or commercial industry synonym
958 Silver	Colloquial Alias	Colloquial or commercial industry synonym
Ag958	Commercial Alias	Colloquial or commercial industry synonym

Applicable Specifications & Product Form ReferencesSPECIFICATION REFERENCE

4 Applicable Standards

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Standards Body	Specification Code	Specification Title / Scope	Relationship Type
UK-STATUTE	British Hallmarking Act 1973	Hallmarking Act 1973 (Schedule 2 Standards of Fineness - Britannia Silver)	Specification Reference
ISO	ISO 9202	Jewellery and precious metals — Fineness of precious metal alloys	Specification Reference
DIN	DIN 17510	Feinsilber und Silberlegierungen (Fine silver and silver alloys)	Specification Reference
British	British Hallmarking Act 1973 Schedule 2 Standards of Fineness	Applicable specification reference.	Specification Reference

Engineering Notice: Applicable specifications establish manufacturing requirements, dimensional tolerances, and test criteria for specific product forms (e.g. bus bar, wire, plate, pipe). They represent applicable technical standards, not alternative or equivalent alloy grades.

Britannia Silver 958 Chemical Composition

Chemical Composition (Weight %) — Elemental limits and values from the cited source. Preserves exact semantic limits (minimums, maximums, and ranges).

Scroll horizontally for full elemental limits

Element	Symbol	Atomic No.	Semantic Basis	Specified Value	Unit	Metallurgical Notes & Qualification	Data Status
Silver	Ag	47	MINIMUM	≥ 95.84	wt%	Ref: ASTM International & ISO / DIN Standards Technical Committees	VERIFIED
Copper	Cu	29	RANGE	4.00 – 4.16	wt%	Ref: ASTM International & ISO / DIN Standards Technical Committees	VERIFIED

* Elemental percentages are expressed in weight percent (wt%). Values represent applicable specification limits. Unspecified trace elements are not fabricated or assumed.Preserves exact semantic basis

Property Display UnitsSwitch between Canonical SI and Source / US Customary units:

Britannia Silver 958 Physical Properties

Source-specific physical properties. Test temperatures are shown only where reported.

1 Parameters

Scroll horizontally for full property parameters

Property Parameter	Canonical SI Value	Semantic Basis	Test Temperature / Context Range	Source Raw Reference	Source Reference	Status
Density	10.4 g/cm³	TYPICAL	Test Temp: 20 °C	10.40 g/cm³	ASTM International & Standards Technical Committees	VERIFIED

Britannia Silver 958 Thermal & Thermodynamic Properties

Phase change temperatures, thermal conductivity, specific heat, mean coefficients of thermal expansion across standardized temperature ranges, and recommended thermal processing windows.

2 Parameters

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Property Parameter	Canonical SI Value	Semantic Basis	Test Temperature / Context Range	Source Raw Reference	Source Reference	Status
Thermal Conductivity	420 W/(m·K)	TYPICAL	Test Temp: 20 °C	420 W/(m·K)	ASTM International & Standards Technical Committees	VERIFIED
Melting Range (Solidus-Liquidus)	870 – 940 °C	RANGE	Solidus 870°C, Liquidus 940°C	870 – 940 °C	ASTM International & Standards Technical Committees	VERIFIED

Britannia Silver 958 Electrical Properties

Electrical conductivity and resistivity in their reported units and conditions.

1 Parameters

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Property Parameter	Canonical SI Value	Semantic Basis	Test Temperature / Context Range	Source Raw Reference	Source Reference	Status
Electrical Conductivity	92 % IACS	TYPICAL	Test Temp: 20 °C	92 % IACS	ASTM International & Standards Technical Committees	VERIFIED

Britannia Silver 958 Mechanical Properties

Contextual Mechanical Properties & Tempers: Engineering strength, ductility, and hardness values grouped by product form, temper, and section thickness. Mechanical properties are contextual and not isotropic averages.

Elastic & Baseline Mechanical ConstantsSource-specific measurement conditions

Modulus of Elasticity

78 GPa

Product Form:

Temper / Condition:

Showing 4 of 4 conditions

Scroll horizontally for all conditions & tempers

Product Form	Temper / Condition	Section Size	Tensile (UTS)	Yield Strength	Elongation	Shear Strength	Fatigue Strength	Hardness (Scales Preserved)	Status
Strip, Sheet, Wire	Annealed (Soft) Source values and qualifiers Yield Strength (0.2% Offset): ≥ 80 MPa (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510 Ultimate Tensile Strength: ≥ 185 MPa (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510 Elongation at Break: ≥ 35 % (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510	—	≥ 185 MPa	≥ 80 MPa	≥ 35 %	—	—	—	VERIFIED
Strip & Wire	Hard Drawn (50% reduction) Source values and qualifiers Yield Strength (0.2% Offset): ≥ 300 MPa (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510 Ultimate Tensile Strength: ≥ 350 MPa (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510 Elongation at Break: ≥ 4 % (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510	—	≥ 350 MPa	≥ 300 MPa	≥ 4 %	—	—	—	VERIFIED
Standard Product Form	Annealed (Soft) Source values and qualifiers HV Hardness: 48–62 HV (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510	—	—	—	—	—	—	48–62 HV	VERIFIED
Standard Product Form	Hard Drawn (50% reduction) Source values and qualifiers HV Hardness: 105–125 HV (TYPICAL)ASTM International & ISO / DIN Standards Technical Committees — ASTM B742, ASTM B413, ISO 9202, DIN 17510	—	—	—	—	—	—	105–125 HV	VERIFIED

Hardness Integrity Notice: Rockwell B (HRB), Rockwell F (HRF), and Superficial 30T (HR30T) scales are reported on their measured scales without cross-scale mathematical conversion.

Source: See fact-level citations

Britannia Silver 958 Processing & Fabrication

Machining, joining, forming, and thermal processing ratings cataloged from the cited authoritative technical reference.

Source: ASTM International & ISO / DIN Standards Technical Committees

Machinability

Rated at approximately 35% relative to C36000. Softer and more ductile than sterling silver; tends to form continuous chips requiring chip-breaker tool geometries.

Weldability & Joining

Readily brazed using silver-bearing filler metals. Less prone to deep firescale oxidation than sterling silver due to lower copper fraction.

Heat Treatment & Working Ranges

Annealed at 450°C to 550°C for 20 minutes, followed by water quench. Demonstrates minor precipitation hardening capability due to copper supersaturation.

Forming & Cold Working

Superb spinning and deep drawing performance; requires fewer intermediate annealing steps than 925 sterling.

Practical Engineering & Fabrication Notes

By Mat Grades Editorial Desk · Updated 2026-11-14. Use alongside the specified product standard and supplier certificate.

Machining & shop-floor behavior

The cataloged machining note for Britannia Silver 958 states: Rated at approximately 35% relative to C36000. Softer and more ductile than sterling silver; tends to form continuous chips requiring chip-breaker tool geometries. A relevant hardness example is HV Hardness: 48–62 HV (typical; Annealed (Soft)). Use that supplied condition for a trial of the difficult feature. Record tool changes, burr removal, unclamped dimensions and accepted parts per hour. Relative machinability ratings from different reference scales should not be compared as if they were one common test.

Weldability, brazing & joining

The available joining assessment states: Readily brazed using silver-bearing filler metals. Less prone to deep firescale oxidation than sterling silver due to lower copper fraction. The first cataloged strength example is Yield Strength (0.2% Offset): minimum 80 MPa (typical; Annealed (Soft), Strip, Sheet, Wire). Assess the final part after joining or thermal processing. Include distortion, cleanup and inspection in the quotation. A material designation or favorable process rating is a starting point for qualification, not evidence that an untested joint meets the drawing.

Corrosion & service environment

Distinguish appearance, electrical contact behavior and mechanical wear in the service requirement. Tarnish resistance is not the same as freedom from surface films in every atmosphere. Check the mating material, cleaning method and final condition rather than using nominal purity as the only acceptance criterion. The recorded thermal example is Thermal Conductivity: 420 W/(m·K) (typical; ; test temperature 20 °C). State the exposure and inspection access in the design record so that a change of installation or cleaning method triggers a review. The selected composition entries are Ag minimum 95.84 wt%, Cu 4–4.16 wt%. Chemistry documents identity; it does not establish fluid compatibility.

Selection trade-offs & applications

Use UK-HALLMARK 958, ISO Ag958, DIN Ag958 to identify the candidate, then specify the product form and delivered condition separately. The catalog lists Cold-spun metal vessels and complex holloware as an application example. The related candidate Sterling Silver 925 is linked for comparison; its commonly compared relationship must be checked before substitution. Compare the complete route through machining, joining, finish and inspection. Keep the certificate, required test location and acceptance criteria with the first-article record. A later change of grade, condition or source should be assessed against that same requirement.

Technical references: ASTM International & ISO / DIN Standards Technical Committees

Britannia Silver 958 Equivalent & Comparable Grades

Comparable Grades & Cross-References: Carefully classified cross-reference relationships for Britannia Silver 958. Comparable does not mean equivalent.

Scroll horizontally for relationship classifications & comparisons

Related Material	Family	Relationship Classification	Metallurgical Notes & Differences	Status	Action
Sterling Silver 925	Silver & Silver Alloys	Commonly Compared	Britannia 958 is softer and more ductile in the annealed condition (55 HV vs 70 HV, elongation 38% vs 32%), facilitating deep spinning with fewer intermediate anneals than sterling.Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost).	VERIFIED
Fine Silver 999	Silver & Silver Alloys	Commonly Compared	Britannia 958 offers 63% higher yield strength (90 MPa vs 55 MPa) while retaining 92% IACS conductivity.Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost).	VERIFIED

Related Engineering & Metallurgy Guides

Contextual technical guides explaining degradation mechanisms, testing methodologies, and selection criteria relevant to Britannia Silver 958.

Material Selection12 min read

Density of Silver: Pure, Sterling, Temperature Effects & Calculator

Silver possesses the highest electrical and thermal conductivity of any metallic element, accompanied by a solid room-temperature density of 10.49 g/cm³ (10,490 kg/m³). Because common alloying additions—chiefly copper—possess lower densities, precision volumetric measurement provides a fundamental non-destructive methodology for alloy purity and fineness verification.

Author: Mat Grades Editorial DeskRead Guide →

Sources

Sources & Provenance Trail: Authoritative reference publications, standards specifications, and data registers cited across this material record.

ASTM International & Standards Technical CommitteesStandard Specifications for Silver & Silver Alloys (ASTM B742, ASTM B413, ISO 9202, DIN 17510)

STANDARDS ORG

Authoritative data harmonized across ASTM B742, ASTM B413, ISO 9202, DIN 17510, British Hallmarking Act 1973, and ASM International monographs.

Issuing Body: ASTM International & ISO / DIN Standards Technical CommitteesRevision: ASTM B742-20 / ISO 9202:2019 / DIN 17510View Source Record ↗

Intellectual Property & Provenance Notice: Mat Grades cites technical literature from recognized industry associations and standards organizations. Underlying technical standards and publication data remain the intellectual property of their respective issuing organizations.