[Special topic of film performance and measurement knowledge] - Determination of film washability

Determination of the scrub resistance of the coating film is a method to evaluate the stability performance of the coating during the scrubbing process. It is mainly used to test the durability and scrub resistance of the coating during the scrubbing process. Especially for wall coatings and wood coatings, etc.

Determination of the scrub resistance of the coating film is usually tested by the scrub test, which can place the coating sample in the scrub instrument and perform multiple scrub cycles to test the durability and scrub resistance of the coating during the scrub process. During the test, parameters such as brush head material, brush head hardness, and scrubbing speed can be adjusted to simulate different scrubbing environments. During the test, changes in properties such as appearance, color, adhesion, weight and hardness of the coating sample are detected to evaluate the scrub resistance of the coating.

The determination of the scrub resistance of coating films can be used to evaluate the durability and stability of various types of coatings, such as wall paints, furniture paints, packaging and printing coatings, etc. By measuring the performance change of the coating during the scrubbing process, the durability and life of the coating can be predicted, and basic data can be provided for formulating coating maintenance and improvement programs.

The following are the steps for the determination of the scrub resistance of the coating film:

Sample preparation: Apply the paint on a suitable substrate. After the paint is dry, use fine sandpaper to polish the surface of the film to clean the surface.

Scrubbing solution preparation: Prepare the scrubbing solution as a standard solution. Usually a soap solution or an aqueous solution of sodium dodecylbenzenesulfonate is used.

Scrubbing: Apply the scrubbing solution evenly on the surface of the sample, and scrub with a certain force and speed. Generally, the washing time is 1 minute, and the number of washings is 10 times. Rinse the surface of the sample with clean water after each wash, and wipe the surface clean.

Inspection: Check whether the surface of the sample has peeling, discoloration, etc., and record the number of times of washing and the time when the phenomenon occurs.

Evaluation: To evaluate the washing resistance of the coating film, it can be evaluated according to the phenomenon on the surface of the sample and the number of times of washing. Generally speaking, a paint that can withstand 10 times of washing without peeling off, discoloration, etc., can be considered to have good washing resistance.

Determination of scrub resistance of coating film 

The national standard "GB9266-88 Scrub Resistance of Architectural Coating Coatings" stipulates that a scrub test machine should be used during the test. After the test plate is fixed with clips, use a bristle brush to rub back and forth on the surface of the paint film at a fixed reciprocating frequency per minute, while continuously dripping Detergent, the test is carried out continuously until the bottom of the paint film is exposed, or the number of times specified in the product standard. It is recommended to use the scrubbing-resistant instrument.