Overview
EN ISO 9117-1:2009 - Paints and varnishes - Drying tests - Part 1: Determination of through-dry state and through-dry time (ISO 9117-1:2009) defines a standardized test method to assess whether a single coat or multi-coat coating has reached a through-dry state after a specified drying period. The procedure can also be used to determine the through-dry time (the elapsed time from application to through-dry). This European adoption by CEN provides harmonized laboratory conditions for quality control, product development and specification compliance.
Key topics and technical requirements
- Scope and purpose: Establishes how to determine if a coating is dry throughout its thickness under standard conditions; optionally used to find the time to reach that state.
- Test principle: A coated test panel is subjected to a controlled local load (gauze over a rubber disc) for a specified period and then rotated 90°; the film is examined for damage to judge through-dry state.
- Apparatus and materials:
- Baseplate and free-sliding plunger with plunger head (≥25 mm diameter).
- Rubber disc: ~22 mm diameter, ~5 mm thick, hardness ~50 ±5 IRHD.
- Woven monofilament polyamide gauze (specified thread/aperture), fresh for each test.
- Weights to give a total mass of approximately 1 500 g and a stopwatch.
- Test panels and sampling: Use representative samples per ISO 15528; prepare panels per ISO 1514 and ISO 1513. Typically three panels are used (six if both state and time are determined).
- Procedure essentials:
- Dry/age panels horizontally with free air circulation, shielded from drafts/direct sunlight under specified conditions.
- Apply gauze/plunger, load for (10 ± 1) s, rotate plunger head 90° in ~2 s, then inspect visually.
- Repeat on additional panels; report “through-dry state achieved” or “not achieved”.
- Reporting: Include coating method, dry film thickness, drying/stoving and aging conditions, and the test result. Film thickness measurement references ISO 2808.
Practical applications and users
- Who uses it: Paint and varnish manufacturers, QC/QA laboratories, coating formulators, industrial applicators, specifiers and certification bodies.
- Why it’s used:
- Routine quality control to confirm a batch or coating process produces a through-dry film.
- Comparative evaluation during product development and formulation optimization.
- Contract/specification compliance checks and acceptance testing for single- and multi-coat systems.
- Supporting data for performance claims (e.g., handling, stacking, further processing).
- Practical tips: Follow referenced standards for sampling, panel preparation and thickness measurement; use fresh gauze each test and ensure stable drying conditions as agreed between parties.
Related standards
Keywords: EN ISO 9117-1:2009, through-dry, through-dry time, drying tests, paints and varnishes, test method, coating quality control, film thickness.