2. Bring to boil and then soak in water enclosures with caustic soda concentration 8% of the weight of the paper mulberry, Broussonetia papyrifera bark.5-6 hours, then rinse with clean water (3 times)
2. The shell water soaked and boiled with caustic soda concentration. 8% of the weight of paper mulberry bark for 5 - 6 hours, then wash with clean water (3. Times).