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7.1   Re-reeling

Re-reeling is a process of reeling the raw silk from small reels onto large (standard) reels with a circumference of 150 cm, adjusting the width and weight of skein uniformly. The object of re-reeling is to make standard sized hanks or skeins for marketing purposes. Skeins should have a circumference of 150 cm in accordance with International Standards. Secondly, re-reeling eliminates defects, which might have occurred during reeling.

7.1.1 Re-reeling machine and apparatus

Basically the re-reeling machine consists of various parts and instruments such as the grand reel, reel revolution and stop motion equipment, traverse bar and guider and drying pipe, double thread checker and accessory utensil (see Appendix, Figure 24). The circumference of the grand reel is 1,50 cm and length of the reel rib to be used for five skeins is usually 0.67 meters.

7.1.2 How to re-reel raw silk

1)     Pre-treatment

To obtain best results from the re-reeling process, the sericin gummed at the rib edge of the small reel should be swollen and softened through a dipping process.

  1. Infiltration method by vacuum tank 203 times infiltration with 30-35 C water under 40-60 cm Hg is recommended (see Appendix, Figure 23).
  2. Bath method. Dipping time normally 10-30 minutes, but should be changed depending upon the temperature and concentration of the chemicals used. Currently emulsified oil is recommended for use as a chemical for re-reeling.
  3. Damping method. It is sometimes desirable that the hard gummed raw silk on the small reel be covered with a wet cloth.

2)    Dipping during the re-reeling process

In the case of a double skein, additional water is occasionally needed when there has been inadequate wetting of the raw silk on the small reel. This is accomplished by use of water spray, dipping and wet cloth, for instance.

3)   Re-reeling process

There is a tendency that re-reeling velocity is closely related to the number of breaks of the raw silk, re-reeling efficiency and generation of the gummed skein. Optimum velocity recommended for re-reeling is 150-170 rev./min. for 21-denier and 130-160 rev./min. for 14-denier raw silk. The best temperature and relative humidity of re-reeling is around 41 C, 36 percent R.H. Under this condition the moisture content of raw silk skein immediately after re-reeling reaches 6.2 percent and the raw silk skeins are not stuck together (Table 24).

Table 24. Temperature and humidity of re-reeling in the machine
(S. Kimura, 1964)

Temperature ( C)

Relative humidity

Moisture content of raw silk skein after re-reeling (%)

Appearance of raw silk skein












Over dried

Raw silk should have about 6-8 percent moisture in it after the re-reeling process is finished. The number of grand reels per labourer should be around 15-20 grand reels for 21-denier and 20 grand reels for 14-denier. This will change if the raw silk size, re-reeling velocity and number of thread breaks are not within expected bounds.

7.1.3 Re-reeling efficiency

The standard of the re-reeling velocity (Re.V.) and the re-reelable quantity of the raw silk can be calculated according to the following formula.

For example, 130 x 9 000 20.6/8 x 30 x 1.5 = 158 rev./min.

For the calculation of the re-reelable quantity of raw silk by a grand reel for 8 hours, the following formula should be used.

7.1.4 Silk end tying and skein lacing

The tie end of the raw silk should be tied with cotton year, to find the silk thread end easily during the preparation process for weaving. This is known as silk end tying. Skein lacing keeps the diamond cross originally in the skein place. Five interlacings each at three places on the skein are suitable to prevent tangling (see Appendix, Figure 25).

7.2 Booking and packing

In order to provide proper moisture to the raw silk, the skein should be kept between 20-23 C and 65 to 75 percent relative humidity for several hours prior to booking of the skein.

Standard of skein size:     There are two standard skeins, the 70g known as a single skein and the 125-135g size known as a double skein. The double skein is the preferred version.

Booking of the skeins:     With the bleached cotton rope doubled with 74 plies of 10s yearn, the 30 skeins must be bundled into a book if they are single skeins (5 line 6 stairs). In the case of double skeins, a book consists of 20 skeins.

Packing of a lot:                One bale contains 22-30 books and the standard weight is about 60 kg.

7.3   Storage of silk

Raw silk is vulnerable to heat and sunlight, which may alter its colour, while moisture may cause fungal attack. Thus, precautions must be taken to store raw silk. The storeroom must maintain control over temperature and humidity. BHC powder, chloropicrin, naphthalene and other repellents should be utilized to counter damage from insects. Open skeins should not be stored over long periods; properly packed books and bales can be stored for extended periods under strict atmospheric conditions with no deterioration to the raw silk quality. 

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