ISO 9689:2025 PDF

Overview

ISO 9689:2025 - "Raw optical glass - Resistance to attack by aqueous alkaline phosphate-containing detergent solutions at 50 °C - Testing and classification" - defines a standardized laboratory method to assess and classify the phosphate resistance of raw optical glasses. The test exposes polished glass samples to an aqueous alkaline phosphate-containing detergent solution (tripolyphosphate-based) at 50 °C, measures material loss by weight, and converts that result into a phosphate resistance classification (PR). This standard is intended for samples of raw optical glass used in optical components and production quality control.

Key topics and technical requirements

• Test principle: Immerse polished glass samples in a 0.01 mol/L tripolyphosphate solution at 50 °C, determine mass loss after specified exposure times and compute the time to remove a 0.1 µm surface layer to derive the PR classification.
• Test solution & chemistry: Preparation involves purified pentasodium triphosphate (tripolyphosphate) and dilution to produce a test solution with pH 10.0 ± 0.1 (at 20 °C).
• Sample preparation:
  • Nominal size: (30 ± 1) mm × (30 ± 1) mm × (2.5 ± 0.5) mm after polishing.
  • Lapping and polishing requirements (cerium oxide