FZ/T 70009-2021Test method for relaxation dimensional change and felting dimensional change to washing of wool textiles (English PDF)

7.1 Specimen size

7.1.1 Knitting and braided yarns

7.1.1.1 The knitted fabric according to Appendix A is folded with the front side facing outwards to form a double-layer test specimen, and the three sides are seamed firmly with dimensionally stable sewing threads. The size of the specimen shall at least meet the requirements of 7.1.2.1.

7.1.1.2 The knitting yarn and braided yarn fabric shall be washed using the 1×4G washing program and dried according to 8.4 before testing.

7.1.2 Knitwear

7.1.2.1 The knitted fabric is folded with the front side facing outwards into a double- layer test specimen with an area of approximately 300 mm×400 mm, and a minimum area of not less than 225 mm×300 mm. The ratio of the transverse to the longitudinal direction shall be 3.4.The edges of the test specimen are firmly seamed with dimensionally stable sewing threads.

NOTE. For knitted fabrics without any post-treatment, the specimen shall be washed using the 1×4G washing program and dried according to 8.4 before testing.

7.1.2.2 Sweaters, vests, woolen trousers, woolen skirts, woolen knitted patchwork

garments, socks, small pieces of clothing, etc. are to be tested as a whole piece.

7.1.3 Woven fabrics

The specimen size is 500 mm×500 mm. Fold at 40 mm from the edge of the fabric in the warp and weft directions with the front side facing outwards, press and iron to form a folded edge, and then seam with a chain stitch at 30 mm~35 mm from the crease.

7.2 Marking the specimen

7.2.1 Mark with a knot of sewing thread or a non-fading pen.

7.2.2 The knitting yarn and braided yarn fabric and knitted fabric shall be marked at least 25 mm away from the edge of the specimen, with three groups of marks in the it according to 8.4 and 8.5.

8.3 Felting dimensional change test

8.3.1 The total test load and specimen mass are the same as those in 8.2.1.

8.3.2 Place the load that has undergone the relaxation dimensional change test procedure into the washing machine.

8.3.3 The operation on detergent is the same as 8.2.3.

8.3.4 Carry out the 4G or 4N washing procedure specified in GB/T 8629-2017, and the number of cycles shall be in accordance with the relevant product standards.

NOTE. If multiple washing procedures are required, fresh detergent shall be added according to 8.3.3 before each washing.

8.3.5 After the washing process is completed, remove the specimen, dry it and measure it according to 8.4 and 8.5.

8.4 Sample drying

Use a drying oven for drying, carefully smooth out the wrinkles on the specimen, and lay it flat in the oven specified in 5.2 until it is dry.

8.5 Conditioning and measurement of dried specimens

8.5.1 Spread the dried specimen flat and place it in a standard atmosphere for conditioning for 24 hours.

8.5.2 Measure the distance between each group of marks and calculate the average

value of the dimension in each direction as the relaxed or felted dimension.

8.5.3 Woven fabrics may be ironed flat with a household steam iron weighing 1.0 kg~2.0 kg before conditioning according to 8.5.1.However, if there is obvious felting, ironing is not required.

8.5.4 For routine tests in the factory, wet measurements may be used. The specimens before and after the relaxation or felting washing process shall be placed in a water tank specified in 5.5 filled with 20 mm deep cold water for wet measurements.