The determination of the residue on ignition is carried out according to ISO 1762 (525 °C), ISO 2144 (900 °C) or DIN 54370 (525 °C and 900 °C).

The ash residue is also referred to as ash. It is the portion of the sample that is present after complete combustion of a sample and annealing of the residue under specified conditions until the mass is constant. It is a sum parameter of inorganic fractions in fibrous materials and papers.

The proportion of calcium carbonate can be calculated from the difference between the residue on ignition at 900 °C and 525 °C. The residue can be further quantified by further investigations, e.g. spectroscopically. The residue can be further quantified by further investigations, e.g. spectroscopically.