This part of ISO 787 specifies a general method of test for determining the pH value of an aqueous suspension of a sample of pigment or extender. When this general method is applicable to a given pigment or extender, only a cross-reference to it should be included in the International Standard relating to that pigment or extender, with a note of any detailed modification which may be needed in view of the special properties of the material in question. Only when this general method is not applicable to a particular material should a special method for determination of pH value be specified.