How to use the initial drying crack resistance tester

The initial drying crack resistance tester is primarily used to determine the resistance of architectural coatings (such as wall paint and putty) to cracking during the initial drying process. It is a device for testing coating performance.

Pre-Test Preparation

Sample Preparation

Stir the test sample thoroughly according to the coating product standard. If the sample is too thick, add thinner in the specified proportion (dilution is not recommended unless otherwise specified).

Prepare a clean test panel (usually asbestos cement board, glass, or tinplate, with standard dimensions, such as 150mm × 70mm × 3mm). Sand the surface of the test panel with sandpaper and clean it to ensure it is free of oil and dust.

Instrument Inspection

Check the level of the tester and adjust it using the bottom leveling screws to ensure it is stable.

Check the temperature and humidity control functions of the drying oven (or constant temperature and humidity device) and set the test environment according to the standard (usually a temperature of (23±2)°C and a relative humidity of (50±5)%. Special coatings require adjustments according to the product standard).

Prepare coating application tools, such as a wet film applicator (select the appropriate wet film thickness according to the standard, such as 100μm or 200μm) and a scraper. Ensure that the tools are clean and free of residue.

Environmental Calibration

Start the drying oven. After the temperature and humidity stabilize at the set values, maintain the temperature for at least 30 minutes to ensure that the environmental parameters meet the test requirements.

Test Procedure

Coating the Sample

Place the prepared test panel horizontally. Use the wet film applicator to evenly coat the test sample on the panel, ensuring a uniform coating thickness (maintain consistent coating direction to avoid bubbles or uneven thickness caused by repeated coating).

If multiple panels are to be tested in parallel (typically three parallel panels), ensure consistent coating conditions (thickness, speed, and direction) for each panel.

Place the Sample

After coating, immediately place the test panel horizontally in the tester's sample holder (with at least 50mm between panels to prevent interference with drying). Record the start time.

Ensure the test panels are located within the effective working area of ​​the drying oven, away from direct airflow or localized temperature fluctuations.

Observation and Recording

Observe the test panels at the specified time intervals (e.g., 1 hour, 2 hours, 4 hours, 8 hours, 24 hours, depending on the product standard) and record whether cracks appear in the coating (including the number, size, and distribution of cracks).

Avoid touching the test panels or disturbing the test environment during observation. Use a magnifying glass (e.g., a 10x magnifying glass) to observe for minor cracks.

If no cracks appear within the specified time, continue observation until the test endpoint specified in the standard (usually 24 hours). If visible cracks appear before the specified time, record the time of crack onset.