BS EN ISO 1520-2006 Coatings and varnish Cupping test is an international standard that specifies test procedures for evaluating the cracking and/or separation resistance of coatings, varnishes and related product coatings to metal substrates under standard conditions. Applicable to single or multi-coating systems, coatings can be assessed for compliance with specific requirements by measuring specific indentation depths, or by gradually increasing the indentation depths to determine the minimum depth of coating cracking and/or separation from substrates. This method facilitates quality control and product performance assessment, providing an important reference for the weathering resistance and use performance of Coatings.