Overview
ISO 1888:2022 - Textile glass: Staple fibres or filaments - Determination of average diameter specifies three standardized test methods for determining the average diameter (arithmetic mean of actual diameters) of staple glass fibres or filaments used in textile glass products. The fourth edition (2022) updates procedures and adds Method C (calculation-based determination). The standard is intended for reproducible laboratory measurement and reporting of filament/fibre diameter for quality control, specification, and material characterization.
Key topics and technical requirements
- Three test methods
- Method A (Longitudinal profile): Measure fibre profiles in a liquid mount with a refractive index different from the glass. Use a microscope (≥×400, preferably ×1 000) with an eyepiece micrometer; take 25 random readings; resolution to 0.5 μm or better. Mounting fluids suggested include benzyl alcohol, methyl salicylate or glycerol/water mix.
- Method B (Transverse section): Impregnate yarn with fast-curing resin, cure, polish and cut transverse sections. Under microscope (same magnification/resolution guidance) measure diameters of 25 fibre cross-sections; for oblique cuts measure the smallest axis.
- Method C (Calculation): Compute average filament diameter from yarn linear density (ISO 1889), material density (ISO 12154), and the filament count supplied by the manufacturer. The standard provides the calculation formula and specimen/measurement prerequisites.
- Sample preparation: Guidance on desizing (burn-off in a muffle furnace at 625 °C ± 25 °C if needed) and specimen sizes (e.g., cut lengths ≤ 25 mm for Method A).
- Reporting and expression of results: Express diameters to the nearest 0.5 μm; include method used (A, B or C), identification details, desizing statement if applicable, magnification, average diameter (with standard deviation if appropriate), deviations or incidents, and test date.
Applications and users
- Who uses ISO 1888:2022:
- Glass-fibre manufacturers for product specification and process control
- Independent testing laboratories and QA/QC departments
- Composite and textile fabricators verifying reinforcement properties
- R&D teams characterizing fibre geometry for performance modeling
- Practical uses:
- Ensuring consistent filament diameter for mechanical performance and processing
- Validating supplier claims and part acceptance testing
- Providing traceable measurement data for material selection and design
Related standards
- ISO 472 - Plastics - Vocabulary (terminology)
- ISO 1889 - Reinforcement yarns - Determination of linear density (used for Method C)
- ISO 12154 - Determination of density by volumetric displacement - Skeleton density by gas pycnometry (used for Method C)
Keywords: ISO 1888:2022, textile glass, staple fibres, filaments, average diameter, filament diameter measurement, Method A, Method B, Method C, microscope measurement, linear density.
