This document describes how to test the ash residue (ash content) of paper, cardboard, pulp and cellulosic nanomaterials at 525 ° C. This document applies to all types of sample paper, cardboard, pulp and cellulosic nanomaterials. This document provides measurement procedures for obtaining a measurement precision of 0.01% or better for a residue (ash content) at an ashy of 525 ° C. The test method for residue (ash content) at 900 ° C ashes of paper, cardboard, pulp and cellulosic nanomaterials is described in ISO 2144. In the context of this document, the term "cellulosic nanomaterials" refers specifically to cellulose nanomaterials (see 3.2 to 3.4). . Due to their nanometer-scale dimensions, these cellulose nano-objects can have different intrinsic properties, behavior or functions than those associated with paper, cardboard and pulp.