ISO 14368-4:2020

Overview

ISO 14368-4:2020 - "Mineral and sapphire watch‑glasses - Part 4: Anti‑reflective treatment" defines the terminology, test methods and evaluation criteria for anti‑reflective (AR) treatments applied to watch‑glasses. The standard is written primarily for sapphire watch‑glasses and may be used as a reference for mineral watch‑glasses. It clarifies how to measure optical performance and environmental durability so manufacturers and test laboratories can assess AR coatings consistently.

Key topics and technical requirements

• Scope and purpose: Terms and definitions, separate standardized tests, and evaluation procedures for AR‑treated watch‑glasses. Tests are conducted on new samples and are generally not superimposed; test plans can be agreed between contracting parties.
• Optical characterization:
  • Measurement of luminous transmittance and luminous reflectance using illuminant D65 and a 2° standard observer.
  • Digital integration parameters: spectral range typically 380–780 nm, step width ≤ 10 nm (truncation allowed where justified).
  • Use of spectrocolorimeter/spectrophotometer with integration sphere for Specular Component Included (SCI); geometry options (e.g., 0°:di, 8°:di) are specified and can be agreed between parties.
  • Colour reported in Lab* (or alternative CIE spaces).
• Environmental and mechanical tests: standardized methods and result evaluation for:
  • Adhesive force
  • Humidity test
  • Thermal shock
  • Salt spray (corrosion)
  • Synthetic sweat
  • Abrasion resistance
  • Scratch resistance
  • Sunlight (UV/xenon) resistance
  • Cleaning test
• Evaluation: Visual inspection and comparison with reference samples; appearance checks in accordance with ISO 14368‑3:2003 (Annex A). Acceptance criteria may be tightened by agreement.

Applications and who uses it

• Watch manufacturers specifying AR coatings for sapphire or mineral watch‑glasses.
• Coating suppliers and material engineers validating AR performance and durability.
• Quality control and test laboratories performing optical, environmental and mechanical testing.
• Design and procurement teams ensuring legibility, optical performance and long‑term resistance to wear, moisture, corrosion and sunlight.

Related standards and references

• ISO 14368‑3:2003 (quality criteria and test methods for watch‑glasses)
• ISO/CIE 11664 (colorimetry and illuminants), CIE 15, ISO 4892 (light exposure), ISO 9227 (salt spray)
• ISO 3160‑2, ISO 23160 (related watch case and wear tests)

ISO 14368‑4:2020 provides a consistent, measurable framework for assessing AR treatments on watch‑glasses, supporting reproducible quality control and supplier specifications across the watch industry.