Overview
EN ISO 9117-3:2010 - Paints and varnishes - Drying tests - Part 3: Surface-drying test using ballotini (ISO 9117-3:2010) is a standardized laboratory method published by CEN/ISO for determining the surface-drying characteristics of coatings that dry by air action or by chemical reaction. The method is expressly not intended for stoving products and can be used either as a “go/no-go” compliance check after a specified time or to determine the surface-drying time by repeated assessment.
Key topics and requirements
- Principle: A coated test panel is assessed by pouring small transparent glass spheres (ballotini) onto the surface and lightly brushing them away. The coating is judged “surface-dry” if the ballotini can be removed without damaging the surface.
- Ballotini specification: Glass spheres must be sieved so that none pass a 125 µm sieve and all pass a 250 µm sieve (nominal sizes).
- Test quantities and handling:
- Use approximately 0.5 g of ballotini per test, poured from a height of 50–150 mm (a glass tube ~25 mm internal diameter is recommended to control spread).
- After ~10 s, tilt the panel to ~20° and brush lightly with a soft-haired brush.
- Apparatus: ballotini, soft-haired brush, stopwatch (0.1 s), balance (0.01 g).
- Test specimens and preparation:
- Prepare panels per ISO 1514 and sample per ISO 15528; coating thickness measured in micrometres per ISO 2808.
- If required, apply agreed primer/undercoat and dry as specified before testing.
- Test modes:
- Go/no-go: check surface-dry state after a specified time to evaluate compliance.
- Time-to-dry: test at intervals (using separate panels or distinct panel areas) until surface-dry time is reached.
- Reporting: include product ID, test conditions, substrate preparation, application method, dry film thickness, result (surface-dry at specified time and/or surface-drying time), anomalies, deviations and test date.
Applications and users
This standard is practical for:
- Coatings manufacturers and R&D teams validating formulations and drying additives.
- Quality control and independent test laboratories performing routine acceptance tests.
- Specifiers, contractors and procurement to verify handling, recoating and packaging readiness.
- Regulatory and compliance teams requiring a repeatable method to document surface-drying performance.
Use cases include production acceptance, batch verification, formulation comparison, and determining appropriate handling or recoating windows.
Related standards
- ISO 1513 - Examination and preparation of test samples
- ISO 1514 - Standard panels for testing
- ISO 2808 - Determination of film thickness
- ISO 15528 - Sampling of paints, varnishes and raw materials
Keywords: EN ISO 9117-3:2010, ISO 9117-3, paints and varnishes, drying tests, surface-drying test, ballotini, surface-drying time, coating quality control.
