INTERNATIONALSTANDARD ISO787-3:2000(E) General methods of test for pigments and extenders : Part 3: Determination of matter soluble in water Hot extraction method 1 Scope boiling water, in a sample of pigment or extender. IsO 787-8 specifies a method for determining the percentage by mass of matter soluble in water by cold extraction. state clearly in a specification which method is to be used, and in the test report which method has been used. NOTE The general methods given in the various parts of IsO 787 are usually applicable to any pigment or extender. Thus onlya cross-reference tothe appropriatepart of isO787needs tobe included in the International Standardgiving the specification for that pigment or extender,indicating any detailed modification that may be needed in view of the specia 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of isO 787. For dated references, subsequent amendments to, or revisions of, any of these publications possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IsO and IEC maintain registers of currently valid International Standards. ISO 787-4:1981, General methods of test for pigments and extenders - Part 4: Determination of acidity or alkalinity of the aqueous extract. IsO 787-8:2000, General methods of test for pigments and extenders Part 8: Determination of matter soluble in water Cold extraction method. Iso 1042:1998, Laboratory glassware —One-mark volumetric flasks IsO 15528:2000, Paints, varnishes and raw materials for paints and varnishes — Sampling. 3 Reagent 3.1Water, freshly double-distilled or de-ionized, of pH 6 to 7. Other types of water may be used but only by agreement between the interested parties. 4 Apparatus 4.1 One-mark volumetric flask, of capacity 250 ml, complying with the requirements of ISO 1042. @ ISO 2000 - All rights reserved ISO 787-3:2000(E) 4.2 Membrane filter. Other types of filter may be used but only by agreement between the interested parties. 4.3 Evaporating dish, flat-bottomed, of glass, platinum, glazed porcelain or silica, dried to constant mass. 4.4 Water bath. 4.5 Oven, capable of being maintained at (105 ± 2) °C 4.6 Balance, accurate to 1 mg or better. 4.7 Desiccator, containing an efficient desiccant. 5 Sampling Take a representative sample of the material to be tested, as described in isO 15528. 6 Procedure 6.1 General Carry out the determination in duplicate. 6.2 Test portion The mass of the test portion used shall be chosen according to the type of material and the amount of water- soluble matter in the material. This is particularly important for materials that contain large amounts of matter severaldifferentlaboratories. 6.3 Determination Moisten the test portion in the beaker with a few millilitres of water (3.1). If the material does not disperse easily in water, use a wetting agent. In the case of materials which are not soluble ionic wetting agent such as 10 ml of a 0,01 % solution of an ethylene oxide condensate. If the wetting agent is non volatile under the conditions of test, an appropriate correction derived from a blank test shall be made Add 200 ml of boiling water (3.1) and stir. Unless a different period is specified for the material under test, boil the Cool rapidly to room temperature, transfer the solid and the liquid to the volumetric flask (4.1) and dilute to the mark with water (3.1). Mix thoroughly by shaking and inverting, and filter immediately through the membrane filter (4.2), returning the filtrate to the filter until the filtrate is clear. If the time between the end of the boiling and the beginning of the filtration is specified, it shall be indicated in the test report. Suspensionswhicharedifficulttofiltershallbecentrifuged 2 ISO 2000 - All rights reserved ISO 787-3:2000(E) (