The ISO 19399 standard specifies the method for determining the thickness of Paints and varnish coating films, namely the wedge cutting method (scribing and drilling method). This method uses the difference in film thickness formed by the wedge cutting to determine the thickness of the coating by scribing or drilling holes on the film surface. The standard describes in detail the test steps, required equipment, operating techniques, and accuracy requirements for measurement. This method is suitable for coatings with large film thicknesses, especially for accurate measurement of coating delamination or local film thickness. Through this standardized method, the conformity and repeatability of film thickness measurement can be ensured, providing a scientific basis for Coating quality control and technical evaluation.