Overview - ISO 12775:1997 (glass types and test methods)
ISO 12775:1997 provides a consolidated set of guidelines that surveys the main types of glass of normal bulk‑production composition and the established test methods for their chemical and physical properties. The standard helps manufacturers, users and laboratories compare glass types (e.g., soda‑lime, borosilicate 3.3, alkaline‑earth silicates, lead silicates) and choose appropriate test procedures and classifications for hydrolytic resistance, acid and alkali resistance, and thermal/physical behaviour.
Key topics and technical requirements
- Classification of glass types by typical chemical composition and key oxides (SiO2, alkali oxides, alkaline‑earth oxides, B2O3, Al2O3, PbO). The standard links composition to common fields of application (container glass, laboratory ware, optical glass, etc.).
- Chemical resistance concepts:
- Hydrolytic resistance (water attack) and distinction between glass as a material (bulk, freshly exposed surfaces) and glass as‑delivered (manufactured surface layers).
- Acid and alkali resistance measured by standard test procedures.
- Test methods and classification schemes referenced and explained:
- Grain hydrolytic tests: ISO 719 (98 °C) and ISO 720 (121 °C) - classes HGB / HGA.
- Container hydrolytic tests: ISO 4802‑1 / ISO 4802‑2 - container classes HC (titration and flame‑spectrometric approaches).
- Acid resistance: ISO 1776.
- Alkali resistance: ISO 695 - class A.
- Practical test considerations: sample preparation (etching, grinding, “as‑delivered” vs. “as‑material”), limits and non‑equivalence of classification systems (e.g., HGB 2 ≠ HGA 2 ≠ HC 2).
- Additional physical topics: thermal properties, mean linear thermal expansion and thermoshock endurance are summarized with pointers to relevant methods.
Applications - who uses ISO 12775
- Glass manufacturers for product specification, production control and comparative benchmarking.
- Quality control and testing laboratories that perform hydrolytic, acid and alkali resistance tests.
- Pharmaceutical, food and laboratory equipment producers selecting container and ware materials with required chemical durability.
- Designers of optical, electronic and high‑temperature glassware who need guidance on thermal and chemical performance.
- Standards bodies and procurement specialists for harmonized test selection and vendor compliance.
Related standards (normative references)
ISO 12775 cross‑references many ISO test methods, including: ISO 719, ISO 720, ISO 4802‑1, ISO 4802‑2, ISO 1776, ISO 695, ISO 718, ISO 3585, ISO 7991, and others for laboratory glassware and physical tests.
Keywords: ISO 12775:1997, glass types, hydrolytic resistance, glass test methods, chemical resistance, borosilicate glass, soda‑lime glass, ISO 719, ISO 720, ISO 4802, ISO 695.
