Overview
ISO 24118-1:2023 specifies a standardized stylus contact method for the determination of surface roughness of paper and board (tissue paper excluded). The standard defines the measurement principle, apparatus requirements, sampling and conditioning procedures, test execution, calculation of roughness parameters and reporting rules. It is intended for reproducible, comparable roughness measurements across laboratories and production sites.
Key topics and requirements
- Scope: Applies to all papers and boards except tissue paper; measurement uses a stylus contact method.
- Measurement principle: A stylus under defined contact force scans the sample horizontally at constant speed; surface height is recorded and processed to obtain roughness values.
- Primary parameters:
- Ra (average surface roughness): arithmetic average of absolute deviations from the mean line.
- R: pointwise surface roughness values used to compute Ra.
- M: mean absolute deviation from Ra. Calculation formulas and data-range rules are provided.
- Apparatus specifications:
- Stylus geometry: conical tip with radius 0.5 mm ± 0.025 mm; stainless steel per ASTM A681-08 recommended.
- Contact force: 50.0 mN ± 0.25 mN.
- Traversing speed: 1.0 mm/s ± 0.05 mm/s.
- Measurement travel: instrument must scan at least 30 mm; roughness is evaluated over a run of 5 mm to 25 mm while surfaces move uniformly.
- Instrument accuracy requirement: overall measurement accuracy of ±1% (see standard for full-scale details).
- Sampling & conditioning:
- Lot sampling per ISO 186; conditioning per ISO 187 and testing in the same atmospheric conditions.
- Prepare at least 10 test pieces for machine direction (MD) and 10 for cross direction (CD); specified minimum piece dimensions apply.
- Procedure & reporting:
- Repeat measurements (minimum 10 runs per direction), report individual R and M, grand averages, standard deviation and coefficient of variation, and any deviations from the standard.
- Precision data: Annex B contains interlaboratory repeatability and reproducibility statistics for common paper grades.
Applications and users
ISO 24118-1:2023 is useful for:
- Quality control in paper and board production (surface roughness monitoring).
- Printing and converting operations where surface texture affects ink transfer, print quality and coating performance.
- Packaging development and specification (surface finish affecting lamination, adhesion).
- Test laboratories and R&D groups validating material performance.
- Instrument manufacturers and calibration labs referencing stylus and measurement specifications.
Keywords: ISO 24118-1:2023, surface roughness, stylus contact method, paper and board, Ra, roughness measurement, test method.
Related standards
- ISO 186 - Sampling to determine average quality (referenced for lot sampling).
- ISO 187 - Standard atmosphere for conditioning and testing.
- ISO 5725-2 - Repeatability and reproducibility methodology (precision assessment).
- ASTM A681-08 - Tool steel specification (recommended stylus material).