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T 211 om-93
TENTATIVE STANDARD – 1933 OFFICIAL STANDARD – 1934 OFFICIAL TEST METHOD – 1980 REVISED – 1985 REVISED – 1993 © 1993 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and the Association assume no liability or responsibility in connection with the use of such information or data, including but not limitedto any liability or responsibility under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published.

Ash in wood, pulp, paper and paperboard: combustion at 525°C
1. Scope

This method for determination of ash can be applied to all types and grades of wood pulp paper, and paper products. For the determination ofash by combustion at 900°C, see TAPPI T 413 "Ash in Wood, Pulp, Paper and Paperboard: Combustion at 900°C." 2. Summary

A test specimen is ignited in a muffle furnace at 525°C. A separate test specimen is analyzed for the percentage moisture. The resulting weight of ash and moisture level in the sample are used to calculate the percentage ash present at 525°C on a moisture-free sample basis. 3.Significance

3.1 The ash content of the sample may consist of: (1) various residues from chemicals used in its manufacture, (2) metallic matter from piping and machinery, (3) mineral matter in the pulp from which the paper was made, and (4) filling, coating, pigmenting and/or other added materials. The amount and composition of the ash is a function of the presence or absence of any of thesematerials or others singly or in combination. No specific qualitative meaning is attached to the term "ash" as used in this test method. Where a further qualitative examination of the ash is desired, this method may be used in combination with TAPPI T 421 "Qualitative (Including Optical Microscopic) Analysis of Mineral Filler and Mineral Coating of Paper," and major components of the ash identified.3.2 The combustion of cellulose to form volatile combustion products occurs at about 300°C. For papers or pulp containing no added fillers or coatings, ignition at either 525°C or 900°C will yield essentially identical results of a few tenths percent ash or less. Examples of such papers include "ashless" filter papers manufactured for chemical analysis, or dissolving grade pulps. 3.3 For samplescontaining fillers, coatings or pigments which undergo negligible change in weight upon ignition of either 525°C or 900°C, such as the oxides of silicon or titanium, and where other fillers, coatings or pigments are known to be absent, ignition at either temperature may be taken as a semi-quantitative measure of the percentage of such material present in the sample. 3.4 In most cases, the ashcontent of paper and paperboard will contain inorganic residues from the pulp, inorganic residues from paper making chemicals, and loading or filling materials deliberately added. In such cases, the significance of the ash level determined will vary depending upon which ashing temperature is used and the identity of the materials added.
Approved by the Chemical Properties Committee of the Process andProduct Quality Division TAPPI

T 211 om-93

Ash in wood, pulp, paper and paperboard: combustion at 525°C / 2

3.5 For papers containing only cellulose and calcium carbonate, ignition at 525°C will remove cellulose, and moisture, but will leave as ash the calcium carbonate essentially intact. Ignition at 900°C will convert the calcium carbonate to calcium oxide. In such cases, these methodsmay be used in conjunction to provide a good estimate of added calcium carbonate levels. 3.6 For papers containing cellulose and clays or materials of indefinite composition and/or variable thermal decomposition, significance of ash level may require significant confirmation regarding the materials added, qualitative analysis of the ash as described in T 421, or both, and even then care in...