This test method is useful in determining the approximate amount of nonvolatile inorganic material in wet blue. This may be in the form of salts or oxides of the elements. In a mixed-chrome tannage, the approximate percentage of other elements in the wet blue may be determined by subtracting the chromic oxide that may be conveniently determined on the ash. (See Test Method D 6714.)

The specified temperature of 600°C is high enough to produce a reproducible result but it does not completely dehydrate such oxides as aluminum oxide (Al₂O₃) and chromic oxide (Cr₂O₃). Likewise, such salts as sulfates and phosphates may be incompletely dehydrated, and if alkalis and chromium are present simultaneously, oxidation to chromate may occur. Therefore, caution is advised in drawing conclusions based on quantitative relations of the elements.

1.1 This test method covers the determination of total ash in wet blue and wet white.

1.2 For total ash in wet white, the procedure is identical; substitute wet white for wet blue in the standard.

1.3 Total ash in wet blue may be reported upon a number of different bases (for example, fat-free, moisture-free, as received, excluding chromium, and so forth). Before proceeding with any tests, it is very important to determine upon which basis that the total ash is to be reported and to identify all other test methods that will be required to be executed in order to achieve the determined reporting method.

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

1.5 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.