The standard "ISO 776-2011 Pulp, Determination of acid-insoluble ash" provides a standard method for the determination of acid-insoluble ash content in pulp. Acid-insoluble ash refers to mineral residues that do not dissolve in acidic solutions, such as silicate and Miscellaneous inorganic matter. The method separates and weighs the insoluble residue by ashing the pulp sample and then dissolving the soluble components with acid, thereby determining its content. This standard is applicable to mass analysis of all types of pulp products and is an important tool for quality control and raw material evaluation in pulp production. Its accurate and reliable test method provides a unified reference for the paper industry, helping to optimize the production process and ensure product mass.