These test methods are designed to broaden the scope of the earlier editions of the test method by the inclusion of tall oil and tall oil derived products as test materials and will be referenced in Test Methods D 803.

The acid number is an important property of naval stores products, tall oil, and the products obtained by the fractionation of tall oil. It is the test method widely used to determine the total free acid content of these products.

The potentiometric test method should be used when the most reproducible results are required.

1.1 These test methods are intended for determining the acid number of naval store products as defined in Terminology D 804 including tall oil products, wood and gum rosin, and other related materials. These test methods may not be applicable to all modified rosin products. Two test methods are covered, as follows:

1.1.1 Potentiometric method (referee), and

1.1.2 Internal indicator method (alternate).

1.2 The potentiometric method is suitable for use with both light- and dark-colored products. It should be considered the referee method. The internal indicator method is suitable for use only with light- and medium-colored products with a Gardner color of less than 12. It should be considered the alternate method.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.