CHAPTER 11
RAW SILK TESTING 

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11.1    Introduction

Silk weaving has reached a very high standard of industrial efficiency. In fact, today a number of varieties of silk fabrics are produced on handlooms and sophisticated power looms. This requires different qualities of raw silk. In order to assist the weaving industry in the selection of the required raw silk, it must be first tested and classified. Further, the raw silk reeling industry requires well-defined standards, which can only be achieved by silk testing. As the demand for silk is global and a number of countries compete in the trade of raw silk, it is necessary that there should be industry standards for raw silk quality so as to enable buyers to purchase raw silk at internationally accepted grades. This is the reason why all raw silk produced should be classified following testing.

The testing of raw silk is based on the procedure laid down by the International Silk Association (I.S.A.). This procedure is quite conservative and the equipment used is consistent with traditional patterns when compared to procedures followed for general textile products. The traditional method has been widely preferred in silk producing and consuming countries of the world. The mechanical testing procedure is similar everywhere, but the compilation of test results and standards for various grades differs slightly from country to country.

In 1914, an essay competition was held in New York for quality silk goods. During 1921-1927, silk classification committees were set up. In 1928 and 1929, International Technical Conferences were held in Yokohama and New York, respectively. All silk producing countries such as Japan, China, Russia, France, Italy, etc., and silk consuming countries such as the United Kingdom and the United States, were represented. The organization of the International Silk Association and the organization of the third International Technical Raw Silk Conference in Zurich in 1949 followed by a fourth one in New York in 1950, contributed to placing silk technology and silk research on a global basis. In 1949-1950, a Bulletin was issued by the International Silk Association (I.S.A.) on International Standard Methods for Raw silk Testing and Classification. In 1961 a revision was made and it was decided to divide them into three categories. A second amendment was made in raw silk testing and classification in 1974. Recently, an electronic testing system was introduced into I.S.A.’s methods.

Two main tests are usually applied, namely the conditioned weight test and the test for quality. The quantity tested from a consignment depends on the total weight. Usually, 5-10 bales of 60 kg each or 20 bales of 30 kg each is the unit of testing used for the export of raw silk.

11.2    Quality test

11.2.1    Visual Inspection

This test is conducted on the whole lot of raw silk, which has to be classified. This is carried out in an inspection room, which is well illuminated. There are three main factors that have to be tested. These are:

11.2.2    Uniformity

In this test, the entire lot is inspected to assess the uniformity of colour, lustre and feel. The result is not recorded in the I.S.A. method, but is classified as good, fair and inferior under the Japanese method.

11.2.3    General finish

Here, considering the presence and degree of a number of defects assesses the general finish of the lot. These defects are:

    1. Re-reeling. Gummed skeins; gummed spots on skeins; double ends; irregular traverse and partial flack of traverse.
    2. Finish. Tangled filament, defective lacing, filament out of place in skein (pulled filaments loose).
    3. Arrangement. Lacing of booking card through skeins; non-uniform skeins; wrong twisting; raised filament; streaky filament; cut ends; discoloured skeins; foreign matter on skeins; irregular skeins on book; knots on skeins; skeins or books of different types.
    4. Damage. Books of irregular shape; gummed books, soiled filaments; frayed skeins; insect attached skeins; musty skeins, etc.

The results are expressed in terms such as good, fair, poor or inferior. Outstanding defects are mentioned in the Test Certificate.

11.2.4    Nature

The degrees of Colour and Lustre and the Smoothness or Hand of the lot are inspected and indicated in the following manner:

    1. Colour: light, medium or deep
    2. Lustre : bright, medium or dull
    3. Hand : smooth, medium or rough

11.3 Sample test

After completion of the test on the whole lot, the following tests have to be conducted. To conduct these tests, it is necessary to take out 50 skeins off the lot if the skeins weigh below 120 g. Alternatively, 25 skeins are taken if the skeins weight over 120 g. Having extracted the required number of skeins, the following test is carried out:

11.3.1     Winding test

Equipment required:

Number of sample skeins drawn out for this test should be 40 skeins out of 50 skeins for a lot which weighs approximately 70 g each and 20 skeins out of 25 skeins drawn out for each skein weighing approximately 140 g.

When winding is started only the top half of the sample skeins should be wound. The winding should be carried out at a predetermined speed for a specific duration. The number of breaks that occur should be counted and noted. When breaks occur, it is necessary to note the cause of each break and this should be recorded.

Table 34. Average speed and winding period for winding test

Size under test

Preliminary winding

Average speed (metre/min.)

Winding period (minutes)

      70 g skeins 140 g skeins
12 denier or finer

10

110

60

120

13-18

10

140

60

120

19-33

10

165

60

120

34-69

5

165

30

60

70 or coarse

5

165

20

40

 

The winding speed and duration of winding has also to be adjusted according to the denier of the raw silk being tested. For reference purposes, the different time and speed and other requirements are shown in Table 34.

11.3.2    Size deviation test

Equipment required:

Only a fixed length from each skein is taken for the testing. The highest degree of deviation is noted and compared with the average size deviation of the conditioned weight. When testing raw silk of 33-denier or finer in size, 200 skeins of 450 metres each are taken out by picking out four skeins out of each of the 50 sampling skeins taken from the testing lot. In the case of 34-denier and over, 400 sizing skeins are extracted by picking eight skeins of 112.5 metres in length each from the 50 sample skeins (total length 45 000 metres).

Test

The entire lot of sizing skeins should be in ten separate lots.

Each sizing skein should be weighed on a quadrant scale in each lot separately. The total weight of all the skeins in each lot is therefore obtained. Table 35 indicates the size deviation of the skeins being tested. This table covers the number of skeins in a lot, the graduation in the scale for weighing each skein and all the skeins of a lot together.

Table 35. Number of skins in a lot and graduation in scale

 

Sizes

No. of skeins in a group

Accuracy of scale

Permissible range of denier

For 1 skein

For group

330 denier or finer
        33-49 denier
        50-99 denier
100 denier or coarser

20
40
40
40

0.5 denier
1.0 denier
2.0 denier
5.0 denier

0.5 denier
2.0 denier
2.0 denier
2.0 denier

1.5 denier
4.0 denier
8.0 denier
19.0 denier


If there is a difference in weight beyond the permissible denier indicted in the above table when the weight of the individual skeins are totalled and compared with the result obtained by weighing all the skeins together, the weighing operations both of single skein and the whole lot must then be repeated. The number of individual sizing skeins of each denier size should be noted in the table of frequency distribution.

The size deviation can be obtained by the following formula:

Where tI, t2, t3 ……., tn are the sizes of the sizing skeins in a denier; f1, f2, f3 ……., fn are their frequencies.

N is the total number of sizing skeins.

M is the calculated average size.

The results of the size deviation test are calculated down to two decimal places.

Table 36. An example for size deviation test



Denier

Frequency of each 20 skeins group

Deviation

(x)



fx



fx2

1

2

3

4

5

f

16-1/2

11

 

1

 

1

2
2

-10
-9

-20
-18

200
162

17-1/2

1

1
11

 

11

1
1

3
5

-8
-7

-24
-35

192
245

18-1/2

1
1

1

11
1

11
111

1
11

6
8

-6
-5

-36
-40

216
200

19-1/2

1

1
11

11
1

1
1

1
11

4
7

-4
-3

-16
-21

64
64

20-1/2

11
1

111
11

11
1

1
1111

1
11

9
10

-2
-1

-18
-10

36
10

21-1/2

11111
111

111
111

1111
1

1111

1
11

17
9

0
1

0
9

0
9

22-1/2

1

 

1
11

1
1

1
1

3
5

2
3

6
15

12
45

23-1/2

1

11

 

1
1

11

5
2

4
5

20
10

80
50

23-1/2

1

   

1

1

2
1

6
7

12
7

72
49

 

Group

Sum of 20 skeins

Denier wt. of group

Sum of fine deviations        -238
Sum of coarse deviations   +79
             Sfx                    -159
            ( Sfx )2                 25281
              Sfx2                    1706
Middle of deniers               21D Deviation of class               0.5D
No. of total skeins             100pcs

1
2
3
4
5
sum
mean

406.0D
403.0
409.0
399.5
403.0
2,020.5
20.205

404.5D
404.5
410.0
400.0
402.0
2,021.0
20.21


Maximum size deviation (denier) =

11.3.3    Evenness test

The test is carried out with test samples of a fixed length using a Seriplane. These test samples represent fine passages and coarse ones, divided into 3 groups (Evenness Variation, I, II and III ) according to the degree and fequency of size variations.

Evenness Variation I:   The intensity of variation greater than the V0 panel but does not exceed V1 panel of the Standard Variation Photographs.

Evenness Variation II:    The intensity of variation greater than the V1 panel but does not exceed the V2 panel of the Standard Variation Photographs.

Evenness Variation III:  The intensity of variation, which includes all the variations greater than the V2 panel of the Standard Variation Photographs.

Panel - A panel is a section of raw silk 127 mm wide by 457 mm long uniformly wound from a bobbin on to an inspection board.

In the Japanese method, Variation I is applied not for the major test or auxiliary test but for the optional text.

Apparatus and equipment: Seriplane (127 x 457 mm), Standard Photographs and Illumination room.

Sample: The sample for the test consists of a total of one hundred panels from 50 test samples taken at the rate of two panels from each test sample.

The thread is spaced on the inspection panel according to the size under test as follows:

        9 denier or finer ……………………..133 threads per 25.4 mm
        10 to 12 denier ……………………...114        "              "
        13 to 16 denier ……………………...100        "              "
        17 to 26 denier ……………………. ...80        "              "
        27 to 36 denier …………………….....66        "              "
        37 to 48 denier …………………….....57        "              "
        49 to 68 denier …………………….....50        "              "
        69 to 104 denier ……………………...40        "              "
        105 to 149 denier …………………….33        "              "
        150 to 197 denier …………………….28        "              "
        198 denier or coarser …………………25        "              "

Test:

The test is conducted by the estimator from a position of about 2 metre distance directly in front of the inspection panels, which are placed in such a way that the panel receives the same intensity of light by indirect lighting, over the entire board. On any one side of the inspection board, each stripe found on each panel is carefully compared with the standard variation photographs and the intensity of variation is determined. The frequency of evenness Variation I, II and III found with the 100 panels is recorded separately. The record shows each total frequency of variations grouped in Evenness Variation I, II and III.

The evaluation of evenness in the Indian method (Table 41) is indicated by percentage. Percentage is indicated to the nearest 5 percent starting from 100 percent to 50 percent.

Below 50 percent, it is made to the nearest 10 percent. The record then shows the estimated evenness percentage of each panel, the average evenness percentage of a total of one hundred panels and the low evenness percentage of low panels corresponding to one-quarter of the total panels inspected.

11.3.4    Cleanness test

This test is conducted to ascertain Super Major Defects, Major Defects and Minor Defects. Each defect carries penalty points and the difference of the total penalty points from 100 gives the test result.

Definitions

Cleanness Defects:    These are categorized into three general groups, viz., Super Major Defects, Major Defects and Minor Defects                               .

Super Major Defects: All major defects in length or size which are ten times larger than the minimum size of Major Defects are named Super Major Defects.

Major Defects:                These are divided into five as follows:

  1. Waste. This is a mass of tangled cocoon filaments or fibres attached to the yarn.
  2. Large slugs. These are somewhat thickened places in the thread 7 mm and above in length, or very badly thickened places shorter than 7 mm.
  3. Bad casts. These appear as abruptly thickened places in the yearn due to the cocoon filaments not properly adhering to the raw silk yearn, or caused by feeding more than one cocoon filament at a time.
  4. Very long knots. These are knots, which have loose ends, 10 mm and over, or those made by incorrect tying of threads.
  5. Heavy corkscrews are places in which one or more cocoon filaments are longer than the rest, and give the appearance of a very coarse and large spiral.

Minor Defects: The minor defects are subdivided into four as follows:

  1. Small slugs, which are considerably thickened places in the thread from 2 to less than 7 mm in length, or extremely thickened places less than 2 mm in length.
  2. Long knots are knots, which have loose ends below 10 and more than 3 mm in length.
  3. Corkscrews are places in which one or more cocoon filaments are longer than the remainder, and give the appearance of a thick spiral.
  4. Long loops or loose ends are loops or split ends, 10 mm and above in length, when measured along the filament.
 Various cleanness a)Waste, b) Slug, c) Bad casting, d) Split ends, e) Large loop

Figure 18. Various cleanness
a)Waste, b) Slug, c) Bad casting, d) Split ends, e) Large loop

 

Apparatus and equipment: Standard Photograph for cleanness, Seriplane and lighting equipment.

Sample: The same as given under Evenness test.

Test

In this test the inspector stands in a position of about 0.5 metres (2 feet) directly in front of the inspection panels, under the same conditions of lighting as for the cleanness test. The actual number of cleanness defects of each class and kind of defect described above, are counted on the yarns on both sides of the inspection panel, omitting the parts on its edges. The class and kind to which each defect belongs is determined by comparing it with the Standard Photographs for cleanness defects. The record should indicate the number of defects in 100 panels found by testing and also show the cleanness percentage, which is determined by deducting from 100 percent the total penalty calculated by penalizing each defect with the following rate:

For each super major defect …………. 1.0 percent
For each major defect ……………….. 0.4 percent
For each minor defect ……………….. 0.1 percent

11.3.5    Neatness test

Neatness defects : Imperfection in raw silk yarn, which are smaller than those described as minor cleanness defects are known as neatness defects. Nibs are small thickened places or spots in the yarn less than 2 mm in length. Loops are small open places in the yarn caused by the excessive length of one or more cocoon filaments, less than 10 mm in length when measured along the filament. Hairiness and fuzziness are the conditions of yarn, which show small loose ends of less than 10 mm and fine particles of cocoon filaments protruding from the yarn. Small knots are knots, which have loose ends, less than 3 mm in length. Fine corkscrews are places in which one or more cocoon filaments are longer than the remainder and give the appearance of a spiral.

Apparatus and equipment: The Standard Photographs for neatness defects, Seriplane and lighting equipment.

Sample: The same as given in the Cleanness test.

Test

The test is conducted by the inspector, from a position of about 0.5 metres (2 feet) distance directly in front of the inspection panels, under the same conditions of lighting as for the neatness test. Each panel on any one side of the inspection board is carefully compared with the Standard Photographs for neatness defects and its neatness value is estimated in percentages. From 100 to 50 percent, the estimate should be to the nearest 5 percent. Below 50 percent, it should be made to the nearest 10 percent. The record should indicate the estimated neatness percentage of each panel, the average neatness percentage of a total of one hundred panels and the low neatness percentage represented by the average percentage of the low panels, i.e. on fifth (20 panels) of all panels examined. In the Japanese method, Cleanness and Neatness is represented as a mixed item by deducting the rate of Neatness results from the Cleanness percentage as shown in Table 37.

Table 37. Deducting points by Neatness results

Neatness

Deducting points

Neatness

Deducting points

Above 80
75
70
65
60
55

0
0.25
0.5
0.75
1.0
1.25


50
40
30
20
10


1.5
2.0
2.5
3.0
3.5


11.3.6    Tenacity and elongation test

To test the strength of the raw silk, the breaking point (g per denier) and the degree of elongation (percentage) is carried out on the Serigraph. This test is conducted in a room, which is maintained at a standard temperature of 20C and a humidity of 65 percent.

               Apparatus: Serigraph, sizing reel and scale.

Sample: Ten test pieces taken out of 50 test pieces. From each one of these ten test pieces, ten sizing skeins shall be prepared for tenacity and elongation test.

Test

The sizing skeins to be tested are placed in a room, where standard humidity can be maintained, for a sufficient amount of time to allow them to become adjusted to standard conditions.

Each sizing skein is then tested for tenacity and elongation using the serigraph, which is placed in the room under the same standards of humidity. The tenacity is expressed in grams per denier, while the elongation is expressed in percentage of total stretch of the portion tested. The result is indicated by the average results of ten sizing skeins. The result of tenacity is calculated by omitting the figures after the second decimal.

11.3.7    Cohesion test

By means of the Duplan cohesion tester, the number of frictions required to split silk thread for the purpose of examining the state of cocoon filaments sticking together, can be counted. This test is conducted in a room kept at standard temperature and humidity.

               Apparatus: Duplan cohesion tester.

Sample: the sample for the test should consist of 20 test pieces taken out of 50 test pieces. The yarn should be free from any cleanness defect or apparent evenness defect in the portion, which is to be tested.

Test

The test is performed in a room where standard humidity can be maintained during the test. The maximum speed of stroke should be 140 strokes per min. The machine should be stopped after every ten strokes and every single yarn inspected very carefully to see if there are any open places. As soon as ten different open spaces, 6 mm long and above are observed, they are recorded against the number of strokes which should be considered as the strokes of the thread opened. The record of the test is the average number of strokes of 20 test pieces. The result of cohesion is recorded by omitting the decimal.

11.4   Quantitative test

11.4.1   Conditioned weight test

When weighing the gross weight and the dried weight of raw silk, the conditioned weight is calculated by adding 11 percent (International Standard Regain) to the dried weight.

The conditioned weight of raw silk is obtained as follows:

All skeins of raw silk for the test are put into a room with a constant temperature and humidity for 12 hours. 20 skeins are picked up for a test unit and are then weighed separately as the original weight.

Two skeins are selected from the sample for the conditioned weight test.

The sample skeins are dried in an oven one by one with the drying temperature at 140C. The drying is continued until the different at every weighing (every 5 minutes) is within 0.1 g.

Moisture regain is calculated as follows:

If the different between both skeins in moisture regain is over 0.5%, another one is tested again.

The total conditioned weight of the unit could be obtained from the total original weight multiplying by the following coefficient.

The coefficient of the conditioned weight is obtained by:

Notice:

Where, W is the original weight and W’ is the dry weight.

11.5   Raw silk classification

11.5.1 Grades

For classification purposes, raw silk is divided into three categories according to their sizes:

             1st category : 18 denier and below
             2nd category : 19 to 33 denier
             3rd category : 34 denier and above

The grades are expressed in the following order in all categories of raw silk:

             4A, 3A, 2A, A, B, in I.S.A. Standard (Table 38-1, 2,3)
            and 5A, 4A, 3A, 2A, A, B, C, D in Japanese method (Table 40-1, 2,3)

11.5.2   Grading with the major tests

The grade of a lot in sizes 33 denier and finer (categories I and II) are determined according to the lowest respective percentage of its Size Deviation, Evenness I, Evenness II, Cleanness, Average Neatness and Low Neatness. Whereas the grad eof a lot in sizes 34 denier and coarser (category III) are determined according to the lowest respective percentage of its Size Deviation, Maximum Size Deviation, Evenness I, Evenness II, Cleanness, Average Neatness and Low Neatness as tabulated in the classifications table for each category.

Should any one or more of these results fall below the minimum limits prescribed for a grade, the lot is relegated to the lowest grade.

11.5.3   Degrading with the auxiliary tests

  1. If any one of the Maximum Size Deviation, Evenness III, Winding, Tenacity, elongation or Cohesion tests of a lot in sizes 33 denier and finer, or if any one of the Evenness III, Winding, Tenacity or Elongation tests of a lot in size 34 denier or coarser, is found to be lower than the required value listed in the class of auxiliary tests, then the grade provisionally established in accordance with the preceding paragraph is lowered by as many grades as the difference that exists between the required auxiliary test class and the class actually found. Any difference that is more than one class is deemed as one class is deemed as one class difference with respect to the Maximum Deviation and Evenness Variation III of a lot in sizes 33 denier and finer and Evenness Variation III of a lot in sizes 34 denier and coarser. In case two or more auxiliary test classes are found to be lower than the corresponding values listed in the classes of the auxiliary tests, then the lot is declassed to the lowest auxiliary test class actually found.
  2. In case the result of the visual inspection of a lot is found to be "Slightly Inferior" in its general finish and/or the result of the skein finish inspection in the Winding test of a lot is found to be "Poor", the grade of the lot is the one below that as has been determined in accordance with the preceding paragraphs.
  3. In case the result of the visual inspection of a lot is found to be "Inferior" in its general finish, or in case the number of breaks in the Winding test exceed the limits mentioned below, the lot is determined as B grade (D grade in the Japanese method).

12 denier or finer......…..............breaks 50(75)
13 to 18 denier …………..........breaks 40(65)
19 to 25 denier …………..........breaks (60)
19 to 33 denier …………..........breaks 35
26 to 33 denier …………..........breaks (55)
34 to 69 denier …………..........breaks 25(45)
70 denier or coarser …………..breaks 20(35)

11.6   Miscellaneous tests

11.6.1   Boil-off test for raw silk

a)          United States Method

            a) Boil-off kettle – A suitable receptacle for boiling off the silk.

            b)Oven – Conditioning oven with forced ventilation efficient to dry the skeins within the time specified, positive value control,
               capable of drying the sample skeins at 140C. The conditioning ovens should be equipped with a balance arranged to weigh
               the skeins with an accuracy of one centigram while suspended within the drying chamber, the hold of the skeins to be of such
               type as to insure free access of the dry air to all skins.

Chemical requirements

Moisture and volatile matter at 105C, max. percent …………..10.0
Sum of free alkali or free acid, total insoluble matter in
alcohol, and sodium chloride, max. percent …………................4.0
Free acid calculated as oleic acid, max. percent ………….........0.2
Free alkali, calculated as NaOH, max. percent …………...........0.2
Insoluble matter in water, max. percent …………......................1.0
Titer of mixed fatty acids prepared from soap …………............16 to 26C
Anhydrous soap content, min. percent ………….......................85.0

b)       European Method

    1. Boil-off kettle – A suitable receptacle for boiling off the silk.
    2. Oven – Conditioning even with forced ventilation, positive valve control, capable of drying the sample skeins at 140C. The conditioning ovens should be equipped with a balance arranged to weigh the skeins with an accuracy of one centigram while suspended within the drying chamber, the holder of the skeins to be of such a type as to insure free access of the dry air to all skeins.
    1. Ten skeins, not more than one skein from any one book, are taken to represent a five or ten bale lot. Approximately 10 g is removed from each skein. The silk removed from the original skeins is grouped into two parts of approximately 50 g each and marked, part number 1 and part number 2.
    2. In the case of a single bale, five skeins, not more than one skein per book, should be taken. Two samples of approximately 10 g each are removed from each skein. These ten samples are grouped into two parts, as in (a) above.

               Weight of soap : 25 percent of net weight of silk.

Concentration : 8 g soap per litre of water which
should be demineralized, or at least at 0
(hydrotimetric)

Volume of solution : 35 times the weight of silk.

Carbonate sodium (CO3Na2) : 0.3 g per litre of water in the solution.

                First bath: To consist of demineralized water (or water at 0 Hydrotimetric) at 60C with addition of 2 or 3 g of
                CO3Na2 per litre. The volume of water must be at least five times the weight of the silk.

                Second bath: To consist of water at 60C without carbonate of soda.

11.7  Exfoliation test for raw silk

Approximately twenty-four litres of water are put into the degumming and dyeing tank and the water is heated. Sixty g of sodium metasilicate are thoroughly dissolved in one litre of hot water and poured into the tank. Thirty g of dye are thoroughly dissolved in another litre of hot water and poured into the tank. The solution in the tank is then stirred thoroughly. A special dye known as United States Testing Company Sky blue S due is used. The thermometer should be left suspended in the solution at all times. When the temperature of the solution has risen to 195-200F, the racks holding the frames are placed in the solution and left there for 20 minutes. During the 20minute period, the temperature of the solution should be maintained between 195-200F. The same solution may be used a second time for one or two additional lots (four or eight frames). If the same bath is used a second time, tem g of due are added to the solution, but no additional sodium metasilicate is required. The added dye must be dissolved thoroughly in one-half () litre of water before being poured into the solution. Sufficient hot water should be added to the solution to maintain the level of the solution high enough to cover the frames. The same solution should not be used for more than two degumming and dyeing operations. It is necessary that the tank be drained and thoroughly rinsed at the end of every day even though the solution has been used for only one degumming and dyeing operation. After 20 minutes, the rack is removed from the degumming and dyeing solution and the frames are rinsed in the rinsing tank to remove excess dye. The rinsing tank is filled with warm water and rinsing is carried out by dipping the rack containing the frames up and down in the warm water three or four times. The silk on the frames is then dried thoroughly. The silk can be dried at room temperature or exposing the silk on the frames to a warm air blast or dried on the frames in a suitable warm oven. If the silk is dried in an oven, care must be taken not to scorch the silk.

Perfect                95 and higher
Excellent             85 to 94.99
Good                  75 to 84.99
Fair                     65 to 74.99
Poor                   50 to 64.99
Very poor          10 to 49.99

Dye for exfoliation test, United States method

United States Testing Co., "Sky Blue S. Dye". This dye has the following formula:

  Class Colour Index
Alphazurine A : 16 percent acid 714(NAC)
Wool Violet 4BN : 15 percent acid 698(NAC)
Glauber Salt : 69 percent    

The two (2) dyes (Alphazurine A and Wool Violet 4BN) are strong colours. For this Exfoliation test, Glauber salt could be omitted and less dye required to obtain the desired colour for the test. In that case, the following proportions are suggested:

  Class Colour Index
Wool Violet 4BN : 48 percent acid 698(NAC)
Alphazurine A : 52 percent acid   714(NAC)

 Table 38-1-ISA classification table for raw silk of category I (18 denier and finer)

classification table for raw silk of category I (18 denier and finer)

 Table 38-2-ISA classification table for raw silk of category II

classification table for raw silk of  category II

 Table 38-3-ISA classification table for raw silk of category III (34 denier and coarser)

classification table for raw silk of category III (34 denier and coarser)

  Table 39 - Chinese classification table for raw silk

Chinese classification table for raw silk

 Table 39 - Chinese classification table for raw silk (continued)

Chinese classification table for raw silk (continued)

 Table 40-1 Japanese classification table for raw silk of category I (18 denier and finergif)

Japanese classification table for raw silk of category I (18 denier and finergif)

 Table 40-2 Japanese classification table for raw silk of category II (19 to 33 denier)

Japanese classification table for raw silk of category II (19 to 33 denier)

  Table 40-3 Japanese classification table for raw silk of category III (34 denier and coarser)

Japanese classification table for raw silk of category III (34 denier and coarser)

 Table 41-1 Indian classification table for Class I raw silk (2.0 tex (or 18 denier) and finer)

Indian classification table for Class I raw silk (2.0 tex (or 18 denier) and finer)

  Table 41-2 Indian classification table for Class I raw silk (2.1 to 3.7 tex or 19 to 33 denier)

Indian classification table for Class I raw silk (2.1 to 3.7 tex or 19 to 33 denier)

 Table 41-3 Indian classification table for Class I raw silk (3.8 tex or 34 denier and coarser)

Indian classification table for Class I raw silk (3.8 tex or 34 denier and coarser)

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