"JG/T 343-2011 Classification and Determination of water-absorption of exterior coatings" specifies the determination method of water-absorption of exterior coatings on porous substrates and the corresponding classification standards, including terms and definitions, measurement principles, required instruments and materials, specimen preparation, test procedures, result calculation, Accuracy, grading standards and test report requirements. This standard is applicable to exterior coatings used on porous substrates such as bricks, stones, mortars, and concrete in industrial and civil buildings to evaluate the resistance of coatings to water. During the implementation process, a number of necessary normative documents are cited to ensure the accuracy and comparability of the measurement results.