Procedure 2)Carry out the determination in duplicate at room temperature. Prepare a 10 % (m/m) suspension of the material under test, using the distilled water (clause 3), in the glass container (4.1). Stopper the container and shake it vigorously for 1 min. Allow it to stand for 5 min, remove the stopper and determine, to the nearest 0,1 unit, the pH value of the suspension. If the material does not disperse easily in water, a wetting agent should be used; in the case of materials not soluble in ethanol, up to 5 ml of ethanol may be used but care should be taken to ensure that the minimum quantity is used and that it is neutral and free from pyridine. In the case of pigments soluble in ethanol, a neutral non-ionic wetting agent such as 10 ml of a 0,01 % (m/m) solution of an ethylene oxide condensate should be used. The neutrality of the wetting agent should be checked by making a blank determination. If a wetting agent is used, the volume of the water should be reduced so that a 10 % (m/m) suspension is obtained. The type and quantity of wetting agent used shall be stated in the test report. (NOTE With pigments and extenders of relatively low density, it may be necessary to use a suspension of less than 10 % (m/m). In such cases the concentration of the suspension used should be stated in the test report.) Record the pH values to the nearest 0,1 unit and record the temperature2) of the suspension to the nearest 1 °C. If the duplicate determinations of pH differ by more than 0,3 unit, the procedure shall be repeated.
Freshly distilled water, boiled before use to remove carbon dioxide, or water otherwise prepared of at least equivalent purity. The water shall be boiled and cooled in a vessel made of chemically resistant glass, immediately before use. It shall be boiled for 5 to 10 min only, in order to avoid an increase of its pH value due to alkali dissolved from the glass vessel. Because water rapidly absorbs carbon dioxide, the cooled water shall be protected from access to the atmosphere and shall be stored for not more than 30 min. The closed container should be protected by a soda asbestos tube or similar device
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