[Film Properties and Measurements] - Determination of film water resistance

Coating water resistance measurement is a method to evaluate the stability of coatings in water. It is mainly used to test the durability and water resistance of coatings in water.

Coating film water resistance determination is usually tested using a water immersion test, which can place a coating sample in water to test the durability and water resistance of the coating in water. In the test, the coating sample is immersed in water and tested for a certain period of time. During the test, changes in properties such as appearance, color, adhesion, weight and hardness of the coating sample are detected to evaluate the water resistance of the coating.

Coating water resistance measurement can be used to evaluate the durability and stability of various types of coatings, such as automotive paints, architectural paints, wood paints, etc. By measuring the performance changes of coatings in water, the durability and life of coatings can be predicted, providing basic data for formulating coating maintenance and improvement programs.

The following are several commonly used methods for measuring the water resistance of coating films:

Flooding method

The sample of the coated substrate is placed in water to observe whether the coating film is damaged by water or foamed or peeled off after a certain period of time. Usually, different water immersion times and temperature conditions are set for testing according to the usage and requirements of the coating material. This method is simple and easy to implement, and is suitable for the initial evaluation of the coating.

Spray method

By spraying water on the surface of the coating, it simulates the water and rain weather environment under different conditions, and observes whether the surface of the coating film changes, such as foaming, cracking, falling off, etc. This method is closer to the actual use environment, and has higher reliability and accuracy for evaluating the actual performance of the coating.

Soaking method

After soaking the coating sample in an aqueous solution for a certain period of time, observe whether there are obvious changes on the surface of the coating film, such as foaming, discoloration, cracking, etc. This method can more deeply evaluate the water resistance of the coating, but it requires a certain period of soaking and the operation is more cumbersome.

Circular soaking method

After soaking the coating sample in the aqueous solution for a certain period of time, the sample is taken out of the water and air-dried, and then soaked in the aqueous solution again, and repeated many times to observe the changes on the surface of the coating film. This method is closer to the water erosion and soaking in the actual use environment, and has higher evaluation accuracy and reliability.

The above methods need to be carried out under certain test conditions, such as different water quality, water temperature, soaking time, etc. The specific test conditions need to be reasonably set according to the use environment and requirements of the paint. During the test, attention should be paid to the preparation and treatment of samples to ensure the accuracy and reliability of the test results.

For the normal temperature immersion method, according to the national standard "GB1733- (79) 88 Determination of Water Resistance of Paint Film", put 2/3 of the area of the painted sample into distilled water with a temperature of (25 ± 1) ℃, and take it out after reaching the soaking time specified in the product standard. Visually assess whether there is foaming, loss of light, discoloration and other imaginations, and instruments can also be used to determine the degree of loss of light and adhesion.