ISO 12625-3:2014

Overview

ISO 12625-3:2014 defines a standardized laboratory method for measuring thickness, bulking thickness, apparent bulk density and bulk (apparent specific bulk volume) of tissue paper and tissue products. The method specifies the measurement conditions (static load of 2.0 kPa), apparatus requirements and sample preparation to ensure consistent, comparable thickness and density data across manufacturing, converting and trade activities.

Key topics and requirements

• Test principle: distance measured between a fixed reference plate and a pressure-foot under a specified static load.
• Loading pressure: 2.0 ± 0.1 kPa (single agreed pressure to harmonize industry practice).
• Pressure-foot: circular diameter 35.7 ± 0.1 mm (nominal area 10.0 cm²); faces flat to within 0.003 mm.
• Measuring speed: 2.0 ± 0.2 mm/s; instrument readout resolution 0.001 mm.
• Instrument calibration: use gauge blocks (known to 0.001 mm) and a balance or load cell (up to 300 g, accuracy 0.01 g) to verify pressure-foot load.
• Sample conditioning and sampling: condition to standard atmosphere per ISO 187; sampling guidance per ISO 186.
• Specimen types: single-ply thickness, single-sheet thickness, and bulking thickness (stacks of typically 12 plies; minimum 8 if instrument limits require). Report number of sheets/plies used.
• Calculations: apparent bulk density is calculated from grammage and bulking thickness; bulk is the inverse of density (expressed cm³/g). Grammage determined per ISO 12625-6.
• Documentation: test report requirements and informative annexes covering precision, measurement conditions and foot pressure.

Applications

• Quality control and process monitoring in tissue manufacturing and converting.
• Specification and acceptance testing between suppliers, converters and brand owners.
• Product development and R&D to compare structure (thickness vs. basis weight) and optimize softness/absorbency vs. material usage.
• Commercial and regulatory documentation where consistent, reproducible thickness/density metrics are required (e.g., roll diameter or stack height calculations).

Who uses this standard:

• Tissue manufacturers, converting plants, QC laboratories, materials engineers, procurement teams and standards/regulatory bodies.

Related standards

• ISO 12625-1 - General terms for tissue products.
• ISO 12625-6 - Determination of grammage (used to compute density).
• ISO 187 - Conditioning and testing atmosphere.
• ISO 186 - Sampling procedures.
• ISO 534 - Thickness methods for paper/board (general reference).
• Moisture determination references noted in ISO 12625 series (e.g., ISO 287 / ISO 638).

Keywords: ISO 12625-3:2014, tissue paper thickness, bulking thickness, apparent bulk density, tissue product standards, thickness measurement method.