BS 1955:1981 pdf free download.Method for Determination of dimensional changes of wool-containing fabrics during washing.
1. Scope
BS 1955 specifies a method for the determination of relaxation dimensional change. felting dimensional change and total dimensional change during washing. It is applicable to wool-containing fabrics. including the fabric of complete articles of which the dimensions are less than the specified specimen size (see appendix B).
2. References
The titles of the standards publications referred to in BS 1955 are listed on the inside back cover.
3. Definitions
For the purposes of BS 1955 the following definitions apply.
3.1 relaxation dimensional change. The change that occurs in a fabric after a static soak and a short period of agitation as specified in 9.3.
3.2 felting dimensional change. The change that occurs
in a relaxed fabnc when it is sublected to a period of
agitation as specified in 9.4.
3.3 total dimensional change. The change that occurs in
a fabric after it has been subjected successively to the
conditions specified in 9.3 and in 9.4.
4. Principle
Relaxation dimensional change is determined by recording the changes in dimensions that occur in a fabric during a static soak followed by a short period of agitation in the Cubex under specified conditions. Initial and final dimensions are measured and the relaxation dimensional change in each dimension is calculated by subtracting the initial from the final dimensions.
Felting dimensional change is determined by recording the changes in dimensions that occur in a relaxed fabric during agitation in the Cubex under specified conditions. It is calculated by subtracting the dimensions of the specimen after the relaxation treatment from its dimensions after the felting treatment.
Total dimensional change is determined by recording the total changes in dimensions that occur during the relaxation and felting procedures. It is calculated by subtracting the initial dimensions from the dimensions after the felting treatment.
5. Apparatus and reagents
The following apparatus and reagents are required:
5.1 Cubex international shrinkage testing apparatus (see
appendix C).
5.2 Makeweights (see appendix C) in the form of square pieces with sides measuring 300 ± 30 mm and having a mass of 35 ± 3 g. Each piece shall be made from two layers of knitted polyester fabric sewn together at the edges.
5.3 Steel rule graduated En millimetres.
5.4 Means of producing the atmospheres specified in clause 6
5.5 Buffer solution (pH 7) containing 4.5g anhydrous sodium dihydrogen phosphate plus 8.0 g anhydrous disodium hydrogen phosphate per litre corrected to pH 7. Distilled water is not essential but hard water (i.e. total hardness as CaCO3 greater than 1 00 mg/litre) shall not be used.
5.6 Wetting agent. e.g. sodium dioctyl sulphosuccinate.
6. Atmospheres for conditioning and testing The atmospheres required are those specified in BS 1051 as follows:
(a) for pre-conditioning. an atmosphere of relative humidity not higher than 10 % and of temperature not higher than 55 C.
(b) for condItioning and measuring. the standard atmosphere for testing textiles. i.e. of relative humidity 65 ± 2%andoftemperature20 ± 2°C.
7. Test specimens
7.1 Selection. Specimens shall be selected to be as representative as possible of the sample under test and may be cut from the piece or the garment (if Cut from garments. avoid areas containing trimming, seams, etc.; see B.1 for small articles). Knitted fabrics shall be tested using single thickness specimens unless otherwise agreed between the parties concerned.
7.2 Dimensions. Specimens each having final dimensions of 300 mm (width direction) x 400 mm (length direction) shall be used.
8. Preparation of test specimen
8.1 Treatment of free edges The free edges of double-thickness specimens shall be sewn with dimensionally stable thread (e.g. No. 40 polyester thread) using a chain stitch and stitch length of 2 mm to 3 mm NOTE. If there is a possibility of the fabnc unravelling during agitation, leave about 30 mm of the specimen unsewn in one corner, turn the specimen inside Out and sew the gap.
8.2 Marking of specimen. Place the specimen on a smooth, flat surface and mark it for measurement by using pairs of suitable indicators (see appendix D) 250 mm apart, symmetrically spaced along the width and length of
the specimen. Mark three separate measurements in each direction (see figure 1). Indicate the length direction by means of a suitable mark. See B.2 for the method of marking small articles. It greater accuracy is required, both sides of the specimen can be marked and measured. Place the marks not less than 25 mm from the edges of the specimen.
9. Test procedure
9.1 General
9.1.1 Pre-conditioning. Expose the specimen to the atmosphere specified in clause 6(a) until at is brought to approximately constant mass.
9.1.2 Conditioning and measuring. Expose the specimen to the standard atmosphere for testing textiles as specified in clause 6(b) for at least 4 h or until it reaches equilibrium. Conduct all measurements in this atmosphere.
9.1.3 Method of measuring. Lay the specimen flat and remove wrinkles gently without stretching the specimen. Measure the distance between the centres of each of the pairs of marks to the nearest millimetre.
9.2 Initial measurement. Measure the conditioned specimen using the procedure described in 9.1.3.
9.3 Relaxation dimensional change Place in the Cubex
25 litres of butter solution (5.5) containing sufficient wetting agent (5.6) to ensure adequate wetting without causing foaming
NOTE Approximately 005 % (V/V) wetting agent should suffice. Add the load of mass 1000 ± 10 g, made up of specimens plus makeweights (5.2). not more than half the load being specimens. Ensure that the temperature of the liquor plus load is 40 ± 2 °C at the beginning of the test.
Subject the specimens and makeweights to a static soak for 15 mm. followed by agitation for 5 mm.
Remove the specimens by folding the corners of each to the centre in such a way that the whole specimen can be supported in the hand. Rinse the specimens with as little agitation as possible in three successive baths of clean water at 40°C. Transfer each specimen from bath to bath giving one gentle squeeze to express excess liquor.
Hydroextract the specimens using a laboratory or domestic spin drying apparatus. Fold each specimen as described above and lay it flat against the side of the drum to avoid stretching during spinning. Continue the hydroextraction until no further water is lost.
Dry each specimen by laying it flat on a surface of low frictional characteristics. e.g. smooth plastics or metal. Elevated temperatures may be used if desired, but shall not exceed 55 °C. If air flow is employed, the air velocity shall not be so high as to cause agitation of the specimens during drying.
Condition each specimen according to the procedure described in 9.1.1 and 9.1.2. Measure the specimen according to the procedure described in 9.1.3.