13 July 2012
Scouring Process of Silk
Degumming
A major undesirable constituent part of silk
is ‘silk gum’ or ‘sericin’ about 25% of total mass. Sericin is removed
by degumming. Degumming is the process of removing the sericin, or silk
gum, from silk. Removing the gum improves the sheen, color, hand, and
texture of the silk. Because the gum can serve as a protective layer, it
is typically left on the silk until it is ready to dye. In some cases,
the fabric is woven to completion, and then degummed, to protect the
yarn from abrasion on the loom. The process involved to remove these
impurities is called ‘degumming’ or ‘scouring’ of silk.
 |
| Silk |
Fibroin - 70-80%
Sericin - 20-305
Waxy matter - 0.4-0.8%
Carbohydrates - 1.2-1.65
Inorganic matter - 0.7%
Pigment - 0.2%
The process of eliminating “Gum (sericin)” from raw silk is known as degumming of silk. Degumming of silk involves mainly the removal of sericin from the fibroin. Sericin is insoluble in water. It is comparatively easily hydrolyzed, whereby the long protein molecule of sericin, is broken down into smaller fractions, which are easily dispersed or solubillsed in hot water.
Typical Recipe for Silk Degumming:
Wetting agent……………………=0.5-1.0 g/l
Sequestering agent…………….=1.0-2.0 g/l
Antifoaming agent……………...=0.5-1.0 g/l
Natural soap…………………….=15.0-30.0 g/l
TSP/Soda ash…………………..=1.0-3.0 g/l
Detergent………………………..=1.0-3.0 g/l (not mandatory if use soda)
Temperature…………………….=90-95°C
Time………………………………=90-120 min
pH…………………………………=9.5-10.5
M:L………………………………..=1:10
Working Procedure:
- Set the bath with substrate at room temperature and add soap and other necessary auxiliaries.
- If necessary add trisodium phosphate (TSP) or soda ash to maintain desired pH 9-10.
- Raise the temperature to 95° and run for 2 hours for optimum removal of sericin gum.
- Cool down to 70°C and then drop the bath.
- Wash it with warm and cold water successively.
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