This test method allows the user to make a quick determination of the blueness or yellowness of the tint undertone of titanium dioxide pigments, versus a reference pigment agreed upon by the parties to the test. This is an important measure of tone, since it gives both a measure of effective particle size, and quick approximation of the blue/yellow undertone that can be expected when a coating containing the titanium dioxide is tinted.

Such matters as the vehicle for preparing the dispersions, and the black for tinting have been suggested. However, changes in the components may be made by agreement between the buyer and the seller.

The results obtained with a mechanical muller do not necessarily correlate directly with a practice where different dispersion conditions exist. However, dispersion with a mechanical muller is a quick and inexpensive way of evaluating the undertone of a titanium dioxide pigment.