DIN EN ISO 1 2625-3 - 2005 Tissue paper and tissue products, Part 3: Determination of Film thickness, Expanded Film thickness and apparant volume Density The standard specifies three measurement methods for the physical performance of tissue paper and related tissue products, including Film thickness, Expanded Film thickness and apparant volume Density. The standard provides specific operating procedures applicable to these tests, ensuring the accuracy and repeatability of measurement results. Film thickness determination is suitable for paper under normal conditions, while Expanded Film thickness is the film thickness of the tissue that changes after exposure to moisture. The apparant volume Density test evaluates the tightness and fluffiness of paper towels by calculating the mass per unit volume. This standard is widely used in the quality control and Product Research & Development process of paper products to help ensure the conformity and functionality of paper tissue products.