GB/T 22856-2018Gambiered canton silk fabrics (English PDF)

3.1 Original gambiered canton silk fabrics

Fabric made from mulberry silk fabric that, after being soaked repeatedly in the juice of the dye yam (Dioscorea cirrhosa), is processed by traditional handcraft such as river-mud coating and sun drying, with a glossy black face and a coffee-brown back, the two sides differing in colour.

3.2 Multicolour gambiered canton silk fabrics

Fabric obtained by printing or dyeing original gambiered canton silk; or fabric first printed or dyed and then processed by the traditional gambiered canton silk handcraft.

3.3 Gambiered speckle on the reverse side

A dark coffee-coloured colour difference formed on the back and along both edges of the gambiered canton silk, at places where too much dye yam juice accumulated during soaking and sun drying, or where the selvedges, not smoothed out and turned over during sun drying, were exposed to direct sunlight for too long.

3.4 Gambiered speckle on the face

A glossy dark black colour difference formed on the face after mud coating, at places where too much dye yam juice accumulated during soaking and sun drying.

3.5 Mud speckle

Normally produced original gambiered canton silk differs in colour on its two sides, black on the face and coffee-brown on the back. A mud speckle is a black defect formed when river mud accidentally adheres to the back during the mud-coating process, which cannot be removed by subsequent finishing operations such as washing, sand washing or printing and dyeing.

3.6 Tussah gambiered canton silk fabrics

Original or multicolour gambiered canton silk made from tussah silk fabric by the traditional gambiered canton silk handcraft.

4.1 Content of requirements

The internal quality requirements of gambiered canton silk comprise seven items: breaking strength, fibre content tolerance, seam slippage, tearing strength, dimensional change on washing, dimensional change on dry cleaning and colour fastness. The appearance quality requirements comprise three items: colour difference (compared with the standard sample), width deviation and appearance defects.

4.2 Grading

4.2.1

The internal quality of gambiered canton silk is graded by batch and the appearance quality by piece.

4.2.2

The grade of gambiered canton silk is determined by the lowest grade obtained for internal quality and appearance quality, and is divided into superior grade, first grade and second grade; products below the second grade are off-grade.

4.2.3

The grade of the greige silk fabric used as raw material for gambiered canton silk shall meet the requirements of the second grade or above specified in GB/T 15551.

4.3 Basic safety performance

The basic safety performance of gambiered canton silk shall comply with GB 18401.

4.4 Grading of internal quality

The grading of the internal quality of gambiered canton silk is given in Table 1.

Table 1 - Grading of internal quality (superior / first / second grade):

Breaking strength (a), N >= 200 (all grades)

Fibre content tolerance, %: shall comply with GB/T 29862 (all grades)

Seam slippage (a) (fixed load 67 N), mm <= 6 (all grades)

Tearing strength (a), N >= 5 (all grades)

Dimensional change on washing, %, warp: +1.0 to -3.0 / +1.0 to -4.0 / +1.0 to -5.0; weft: +1.0 to -2.0 / +1.0 to -3.0 / +1.0 to -4.0

Dimensional change on dry cleaning, %, warp: +1.0 to -2.0 / +1.0 to -3.0 / no value given; weft: +1.0 to -2.0 / +1.0 to -3.0 / no value given

Colour fastness (b), grade >=, to water: change in colour 3-4 / 3 / 3; staining 3-4 / 3 / 3

Colour fastness (b), grade >=, to perspiration: change in colour 3-4 / 3 / 3; staining 3-4 / 3 / 3

Colour fastness (b), grade >=, to soaping: change in colour 3 / 3 / 3; staining 3 / 3 / 3

Colour fastness (b), grade >=, to dry cleaning: change in colour 4 / 4 / 3-4; staining 4 / 3-4 / 3

Colour fastness (b), grade >=, to dry rubbing: staining 3-4 / 3 / 3

Colour fastness (b), grade >=, to light: change in colour 4 / 3 / 3

(a) Not assessed for gauze, sheer (xiao) and devore fabrics.

(b) Colour fastness is not assessed for original and multicolour gambiered canton silk greige fabrics that have not undergone finishing.

4.5 Assessment of appearance quality

4.5.1

The grading of appearance quality is given in Table 2.

Table 2 - Grading of appearance quality (superior / first / second grade):

Colour difference (compared with the standard sample), grade >= 4 / 3-4 / 3

Width deviation, %: ±2.0 / ±3.0 / ±4.0

Limit of the total score of appearance defects, points/100 m2: 30 / 60 / 100

4.5.2

The scoring of the appearance defects of gambiered canton silk is given in Table 3.

Table 3 - Scoring of appearance defects (1 point / 2 points / 3 points / 4 points):

1 - Gambiered speckle, streak (a): 30 cm and below / over 30 cm to 50 cm / over 50 cm to 80 cm / over 80 cm to 100 cm

1 - Gambiered speckle, patch (b): 10 cm and below / over 10 cm to 30 cm / over 30 cm to 50 cm / over 50 cm to 80 cm

2 - Mud speckle, streak (a): over 5 cm to 30 cm / over 30 cm to 50 cm / over 50 cm to 80 cm / over 80 cm to 100 cm

2 - Mud speckle, patch (b): over 2 cm to 10 cm / over 10 cm to 30 cm / over 30 cm to 50 cm / over 50 cm to 80 cm

3 - Dyeing and finishing defects: 8 cm and below / over 8 cm to 16 cm / over 16 cm to 24 cm / over 24 cm to 100 cm

4 - Stains and damage defects: - / 1.0 cm and below / - / over 1.0 cm

(a) Long narrow defects with a width of 2 cm or less.

(b) Long patch-shaped defects with a width of more than 2 cm.

4.5.3

Notes on the scoring of the appearance defects of gambiered canton silk:

a) appearance defects are scored cumulatively, within limits;

b) spot-shaped mud speckles below the 2 cm starting point for scoring are scored 1 point in total when 3 of them occur within 1 m; dense spot-shaped mud speckles are scored as patch-shaped mud speckles according to the size of the area they cover visually;

c) mud speckles caused by the workers' fingers when gripping the fabric edge during mud coating, and gambiered speckles on the face or on the reverse side along the selvedges, are not scored when they lie within 4 cm of either edge;

d) inspection is carried out on the side agreed in the contract; where the contract does not specify, the poorer side is inspected;

e) where original gambiered canton silk shows inconspicuous gambiered speckles or other continuous defects throughout the piece, the batch can only be graded as second grade;

f) the cumulative score within 1 m in the warp direction is at most 4 points; a score above 4 points is counted as 4 points;

g) serious continuous defects are scored 4 points per metre; where they exceed 3 m, the piece is downgraded to off-grade;

h) natural crackle and uneven crackle on the fabric are normal features and are not assessed as defects;

i) colour difference within the same piece (uneven shade) of grade 4 or below of GB/T 250 is scored 4 points for each 1 m or less.

4.5.4

The grading score of each piece of gambiered canton silk is calculated by Formula (1), and the result is rounded to an integer in accordance with GB/T 8170:

c = q / (l × w) × 100 ... (1)

where:

c - grading score of the appearance defects of each piece, in points per hundred square metres (points/100 m2);

q - actual total score of the appearance defects of each piece, in points;

l - length of the piece, in metres (m);

w - effective width, in metres (m).

5.1 Test methods for basic safety performance

The basic safety performance of gambiered canton silk is tested in accordance with GB 18401.

5.2 Test methods for internal quality

5.2.1 Test method for breaking strength

In accordance with GB/T 3923.1.

5.2.2 Test method for tearing strength

In accordance with GB/T 3917.2.

5.2.3 Test method for dimensional change

In accordance with GB/T 8628, GB/T 8629-2017 and GB/T 8630. Washable products are tested with procedure 4G of GB/T 8629-2017, and drying is by method A (line drying) of GB/T 8629-2017. Dimensional change on dry cleaning is determined in accordance with GB/T 19981.2; the "sensitive materials" dry-cleaning procedure is selected, and finishing is carried out with a steam iron.

5.2.4 Test methods for colour fastness

5.2.4.1

Colour fastness to soaping is tested in accordance with GB/T 3921-2008, using test condition A(1).

5.2.4.2

Colour fastness to water is tested in accordance with GB/T 5713.

5.2.4.3

Colour fastness to perspiration is tested in accordance with GB/T 3922.

5.2.4.4

Colour fastness to rubbing is tested in accordance with GB/T 3920.

5.2.4.5

Colour fastness to light is tested in accordance with method 3 of GB/T 8427-2008, exposing to the first stage.

5.2.4.6

Colour fastness to dry cleaning is tested in accordance with GB/T 5711.

5.2.5 Test method for seam slippage

In accordance with GB/T 13772.2. The specimen width is 75 mm and the load is set at 67 N.

5.2.6 Test method for fibre content

Qualitative fibre analysis is carried out in accordance with FZ/T 01057 (all parts), and quantitative analysis in accordance with GB/T 2910 (all parts) and FZ/T 01026.

5.3 Inspection of appearance quality

5.3.1 Inspection conditions

For inspection on a warp-direction inspection machine, daylight fluorescent lamps are used as the light source, the average illuminance on the table is 600 lx to 700 lx, and ambient light is kept below 150 lx. Weft-direction inspection may use natural north light, with an average illuminance of 320 lx to 600 lx.

5.3.2 Test method for width

In accordance with GB/T 4666.

5.3.3 Inspection method for appearance defects

5.3.3.1

Inspection may be carried out on a warp-direction inspection machine or on a weft-direction inspection table. Referee inspection is carried out on a warp-direction inspection machine.

5.3.3.2

When a warp-direction inspection machine is used, the machine speed is (15 ± 5) m/min. The speed of weft-direction inspection is about 15 folds/min.

5.3.3.3

The inspector's eyes are about 60 cm to 80 cm from the centre of the fabric surface. Products with a width of 114 cm or less are inspected by 1 person; products wider than 114 cm are inspected by 2 persons.

5.3.4 Test method for colour difference

A D65 standard light source or natural north light is used, with an illuminance of not less than 600 lx. The parts of the specimen being compared shall be aligned in the warp and weft directions, the incident light shall be at an angle of about 45° to the specimen surface, and the inspector's line of sight shall be approximately perpendicular to the specimen surface at a distance of about 60 cm. The assessment is visual, by comparison with the GB/T 250 grey scale.