4.1 For the broad range of commercial rubber grade carbon blacks, tint strength is highly dependent upon particle size. Tint strength can be used as an indication of particle size; however, tint strength is also dependent on structure and aggregate size distribution. Therefore, differences in tint strength within grades of carbon black may reflect differences other than particle size.

Note 1: This test method was developed primarily for the characterization of N100, N200, and N300 series carbon blacks.

4.2 Tint strength values within the carbon black industry have been developed using a Automatic Muller apparatus which is used to prepare carbon black-zinc oxide pastes. A new mixing apparatus, SpeedMixer3 (DAC 150 FVZ), and a corresponding procedure have been extensively studied within D24 and shown to provide equivalent tint strength for all carcass or soft blacks and most tread blacks with the exception of higher surface area N100 types and specialty blacks. Therefore, it is the responsibility of the user of this alternate apparatus to ensure their products will adequately disperse. Disputes arising between a user and producer should be resolved using the Automatic Muller apparatus until ASTM develops adequate precision statements.

4.3 The term ITRB is used in the entire text for both, the original ITRB, used as the first reference material for tint testing, but which is now used up, and the successor reference material, ITRB2.

1.1 This test method covers the determination of the tint strength of carbon black relative to an industry tint reference black (ITRB).

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.