ISO 12625-18:2022

Overview

ISO 12625-18:2022 specifies a laboratory test method for determining the surface friction of tissue paper and tissue products using a contact-type surface tester. The method measures the coefficient of friction (COF) by dragging a defined stylus across conditioned test specimens under controlled contact force and speed, generating friction profiles from which average COF and mean absolute deviation are calculated. The standard provides apparatus tolerances, specimen preparation, test procedure, calculation and reporting rules, and interlaboratory precision data.

Key topics and technical requirements

• Test principle: A U‑tube shaped stylus contacts the specimen with a contact force of 50 ± 1 mN while the specimen travels at 1.0 ± 0.05 mm/s for a total run length of 30 mm. Data between 5 mm and 25 mm are used to calculate results.
• Measurement outputs: Report the grand average COF (µ) and the mean absolute deviation (M) from 10 replicates in both machine direction (MD) and cross direction (CD).
• Specimens and replicates: Minimum specimen size 100 mm × 60 mm; prepare 10 test pieces for MD and 10 for CD.
• Apparatus tolerances:
  • Load measurement accuracy: ±0.5 mN (5–100 mN) and ±0.5% above 100 mN, data acquisition ≥ 10 Hz.
  • Stylus geometry and specimen holder dimensions are defined (stylus bend 0.25 ± 0.002 mm, stylus length 5 ± 0.05 mm; rectangular frame weight 500 mN).
• Calculations:
  • COF at each point µi = Fi / 50 (Fi = frictional force in mN).
  • Average COF and mean absolute deviation computed per specimen (N ≥ 200 data points) then averaged over 10 specimens.
  • Reporting precision: µ and M to two significant figures; standard deviation to three significant figures; coefficient of variation (COV) to one significant figure.
• Conditions and sampling: Conditioning per ISO 187; lot sampling per ISO 186. Precision and interlaboratory performance documented in Annex B.

Applications and users

ISO 12625-18:2022 is used to:

• Characterize surface slip, feel, and handling behavior of toilet tissue, facial tissue, kitchen towels, and converted tissue products.
• Support product development, quality control, acceptance testing, and supplier specifications where surface friction affects performance (e.g., dispensing, stacking, multi-ply cohesion). Primary users:
• Tissue manufacturers, converters and R&D labs
• Quality assurance teams and testing laboratories
• Equipment and instrument manufacturers developing friction testers
• Procurement/specifications teams requiring standardized COF data

Related standards

• ISO 12625 series (other tissue test methods)
• ISO 186 - Sampling to determine average quality
• ISO 187 - Standard atmosphere for conditioning and testing
• ISO 5725-2 - Determination of repeatability and reproducibility (used for precision data)

Keywords: ISO 12625-18:2022, surface friction, coefficient of friction, tissue paper testing, contact-type surface tester, stylus test, MD/CD, test method.