Silk that retains its natural sericin is called raw silk. The gelatinous nitrogenous protein is frequently left in place during much of the processing of silk fiber because it provides a certain amount of protection to the delicate strands. However, the sericin is usually removed in the yarn or fabric stage by subjecting the material to boiling water and soap. The result is a very soft, lustrous, semitransparent silk that may be reduced in weight by as much as 30 percent. Beautiful, relatively strong, and highly accepting of dyes, this final material is a popular choice for fine garments and textiles that are in high demand around the world.