BS 3568:1988 pdf download.Determination of solubility of wool in alkali.
1 Scope
This British Standard describes a method for determination of the solubility of wool in alkali. This
procedure is applicable to wool textiles in any form, i.e. loose fibre, silver, roving, yarn or fabric, but is not applicable if the specimen has been dyed with any metallized dye.
NOTE The titles of the publications referred to in this standard are listed on the inside back cover.
2 Principle
A test specimen is immersed in a solution of sodium hydroxide of known concentration under specified conditions of time, temperature and volume. The loss in mass is determined as the difference between the dry masses of the test specimen before and after treatment.
3 Reagents
3.1 Sodium hydroxide solution, c(NaOH), 0.1 mol/L.
3.2 Acetic acid solution. Dilute 10 mL of glacial acetic acid, approximately 99.7 % (m/m), Ô approximately 1.06 g/mL, to 1 L with water (3.3).
3.3 Water, complying with grade 3 of BS 3978.
3.4 Petroleum spirit, boiling range 40 °C to 60 °C.
4 Apparatus
4.1 Soxhlet extraction apparatus, complying with BS 2071.
4.2 Water-bath, thermostatically controlled at 66 ± 0.5 °C.
4.3 Conical flasks, 100 mL capacity, fitted with stoppers.
4.4 Sintered-glass filter crucibles, 30 mL capacity, of porosity P160 complying with BS 1752.
NOTE If possible, these crucibles should have ground glass stoppers.
4.5 Filter-flask, filter-pump and adaptor
4.6 Ventilated oven, for drying specimens at 105 ± 3 °C.
4.7 Stoppered weighing bottles, for weighing the test specimens.
4.8 Balance, accurate to ± 0.0002 g.
4.9 Desiccator
5 Test specimens
Take a sample representative of the bulk and not less than 10 g, sufficient to provide wool for the
following test specimens:
a) one test specimen weighing approximately 1 g for determining the dry mass (see 6.2);
b) two test specimens each weighing approximately 1 g for determining the solubility in alkali (see 6.3).
NOTE 1 If it is suspected that the sample contains acid (see 6.4) two further test specimens each weighing approximately 2 g may be taken from the sample for determining acid content by the method described in BS 6981.
NOTE 2 Useful information on sampling is given in BS 2545. NOTE 3 The precision of results may be quite high given a very uniform sample, but, for example, with samples from bleached wool, or with samples having an alkali solubility of 20.0 % (m/m), the variations within the batch may be ± 2 % or more and fresh test specimens may be needed.
6 Procedure 6.1 Preparation of sample Extract the sample in the Soxhlet extraction apparatus (4.1) with petroleum spirit (3.4) for 1 h at a minimum rate of six cycles per hour. Allow the petroleum spirit to evaporate and then remove all vegetable and other obvious foreign matter. Disintegrate the sample into short lengths of approximately 10 mm and allow it to come to equilibrium within the laboratory atmosphere.BS 3568 pdf download.