The ISO 1518-1 standard specifies a test method for the scratch resistance of Paints and varnishes using a constant load method. This method assesses the scratch resistance of coatings under external force by applying a scribe of constant force to the surface of the coating to reflect its durability and surface strength. The standard describes in detail the test equipment, sample prepative, operation steps and result evaluation requirements to ensure the accuracy and repeatability of the test. This method is widely used in Coatings research and development, quality control and product performance comparison. It is particularly suitable for evaluating the performance of coatings under mechanical damage conditions. It provides an important basis for optimizing formulation design and improving coating durability.