Enamelled Watch Component Alloy Selection to Prevent Tarnishing

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Solution Overview

Problem

Existing enameled components for watches and jewelry often suffer from surface defects such as oxidation, sulfidation, and tarnishing after the firing process, leading to aesthetic issues and the need for costly visual inspections and potential reworking.

Innovation Solution

The use of specific metallic alloys for the base substrate, such as those comprising at least 725 parts per thousand gold, 900 parts per thousand silver, or 825 parts per thousand platinum, along with additional metals like Ag, Pd, or Cu, to prevent oxidation, sulfidation, and tarnishing, and to achieve distinct enamel colors by varying the substrate composition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional metallic substrates are used for enameled components, then the firing process can be performed, but oxidation, sulfidation, and tarnishing occur on the substrate surface leading to aesthetic defects

Engineering Contradiction:
Improvesurface qualityVSAvoidoxidation and tarnishing
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the metallic substrate by specifying precise alloy formulations (e.g., gold with specific copper or silver content, platinum with specific copper content, silver with specific palladium content). These parameter changes in substrate composition directly prevent oxidation and sulfidation during firing, eliminating surface defects without requiring additional protective layers or process modifications.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If visual inspections are implemented after firing to detect surface defects, then defective parts can be identified, but production time increases and productivity decreases

Engineering Contradiction:
Improvedefect detectionVSAvoidproduction speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-selecting specific metallic substrate compositions that are inherently resistant to oxidation and sulfidation during firing. This preliminary choice of material composition prevents defects before they occur, eliminating the need for post-firing visual inspections and associated productivity losses.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If the same enamel layer is applied to different substrates, then manufacturing simplicity is maintained, but color consistency cannot be achieved across different substrate compositions

Engineering Contradiction:
Improveenamel application processVSAvoidcolor consistency
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies local quality by tailoring the substrate composition specifically for each desired enamel color outcome. Different metallic alloy formulations are selected based on the specific color requirements, creating a localized optimization where each substrate-enamel combination is precisely matched to achieve the target aesthetic result while maintaining manufacturing simplicity.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces the risk of surface defects and eliminates the need for post-firing inspections, ensuring consistent and aesthetically appealing color variations in enameled components.

Implementation Method 1

the base substrate comprises a principal component chosen from Au, Ag, Pt, and at most 250 parts per thousand by mass of one of the group consisting of Au, Ag, Pd, Pt, Cu

Methodology Applied
Scientific EffectOxidation resistance: Oxidation

Implementation Method 2

the uncoated portions of the base substrate are free from oxidation, sulfation, and/or tarnishing after the enamel firing process

Methodology Applied
Scientific EffectSulfidation resistance:

Implementation Method 3

an enamel layer, supported by the base substrate and leaving parts of the base substrate uncovered after a firing process of the enamel layer

Methodology Applied
Scientific EffectFiring:

Implementation Method 4

the first part of the enamel layer supported by the first basic substrate has a different color from the second part of the enamel layer supported by the second basic substrate

Methodology Applied
Scientific EffectAlloy composition effect on color:

Data Source

PatentEP4685267A1Enamelled component for a timepiece or piece of jewellery
Publication Date: 2026.01.28 RICHEMONT INTERNATIONAL SA
  • EP4685267A1 patent drawingFigure 1~2
  • EP4685267A1 patent drawingFigure 3~4
  • EP4685267A1 patent drawing

AI summary

The invention relates to an enameled component (100) for a watch or jewelry piece, comprising at least: - a base substrate (10), formed of a metal alloy, - an enamel layer (20), supported by the base substrate (10) and leaving parts of the base substrate (10) uncovered after a firing process of the enamel layer (20), characterized in that the uncovered parts of the base substrate (10) are free from oxidation, and/or sulfation and/or tarnishing after the firing process of the enamel layer (20).