Overview
ISO 16532-2:2007 specifies a surface repellency test to determine the grease resistance of paper and board. The method establishes an approximate level of grease resistance by assessing surface repellency and anti-wicking behavior of materials that are internally or surface sized with organophobic treatments (for example, fluorocarbons). It is intended for applications where surface staining from fats, oils or greases is aesthetically unacceptable (e.g., food and pet-food packaging). This part covers the kit-drop test only - it does not measure grease permeability through the sheet (see ISO 16532-1 for permeability testing).
Key topics and requirements
- Principle: Apply drops of numbered Kit test solutions (castor oil diluted with toluene and n‑heptane) to the paper surface; the highest-numbered solution that does not cause darkening (wetting) is the Kit rating.
- Kit solutions: Mixtures of castor oil, toluene and n‑heptane are prepared per Annex A (solutions numbered 1–12). Weight is used for castor oil; volumes for solvents. Stock and test bottles must be tightly closed and solutions renewed regularly.
- Reagents & safety: Castor oil, n‑heptane, toluene (analytical grade). Warning: solvents are highly flammable and pose health hazards - follow laboratory safety procedures.
- Apparatus: Balance, graduated cylinders, glass test bottles with droppers, absorbent tissue, conditioned bench/area with bright uniform lighting.
- Sampling & conditioning: Sample selection per ISO 186; condition samples at 23 °C ±1 °C and 50 % ±2 % RH (ISO 187).
- Test pieces & procedure: Cut at least ten pieces (≥50 × 150 mm). Carry out at least five determinations per side: from ~10 mm height release a drop, time 15 s, wipe excess, inspect immediately for darkening. Determine Kit rating for each piece and compute the mean (rounded to the nearest even number), plus min/max.
- Precision: Repeatability and reproducibility were evaluated in an interlaboratory study; mid-range Kit ratings show greater interlaboratory variability due to subjective end-point detection.
Applications and users
- Packaging converters and manufacturers assessing grease resistance of food-contact cartons, pet-food bags, bakery or confectionery wraps.
- Quality control and test laboratories performing routine surface repellency tests.
- Product developers and specifiers selecting surface treatments (e.g., fluorocarbon sizing) to reduce grease spotting.
- Procurement and compliance teams specifying acceptance criteria for packaging materials.
Related standards
- ISO 16532-1 - grease permeability method (measures permeation rather than surface repellency)
- ISO 186 - sampling to determine average quality
- ISO 187 - standard atmosphere for conditioning and testing
Keywords: ISO 16532-2:2007, grease resistance, surface repellency test, Kit rating, paper and board, castor oil, toluene, n‑heptane, packaging testing, food packaging.