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Cocoons are sorted according to color and texture. For reeling, the unpierced cocoons that are stifled by heat are used. Cocoons are soaked in a basin of water at 140° F to soften the silk gum, or sericin. Filaments from several cocoons are grouped together.

Fibers are threaded through a small hole or eye in the reeling frame and then are twisted with several fibers and threaded through another eye. Further twisting occurs when the yarns are wound, or reeled. But the filaments adhere together because of the natural gum secreted by the silkworm. In this condition the thread is too thin and weak to be used without further twisting - called throwing. Sometimes single strands of thread are doubled and twisted. For example, yarns to be used for lengthwise or warp yarns of a fabric must be very strong to withstand the strain of wear. Accordingly a silk warp yarn is made of several single yarns twisted (with a left-hand twist) to the right. Twisting increases the strength of a yarn. Yarns made of reeled-silk threads twisted together are called thrown silk.

Each woman works at a copper bowl of hot water, into which cocoons are plunged. Several sharp dabs with a brushwood brush loosen the coarse outer covering. Then the tiny strands of silk are reeled off, passing through glass guides on their way to the reels in the background and in the process of being twisted with from 2 to 6 other strands. These yarns are wound on spools or in skeins, ready for the weavers. To facilitate handling, oils may be added to the gum weight by the throwster.

Before silk can be reeled from the cocoon, long, tangled ends must be removed so that an end can be found with which to start the reeling process. The tangled ends are put aside because they cannot be reeled. Likewise, when most of the fiber has been reeled from a cocoon, there may be short lengths. These short pieces are laid aside also. Only about half of the silk of a cocoon is fit to be reeled. The rest is used in inferior silk cloth.

When yarns are prepared for weaving, the skeins of yarn are boiled in a soap solution to remove the natural silk gum or sericin. The silk may lose from 20 to 30 per cent of its original weight as a result of boiling. As silk has a great affinity for metallic salts such as those of tin and iron, the loss of weight is replaced through the absorption of metals. Tannin may also be used as a weighting material. Thus, a heavier fabric can be made at a lower price than that of pure silk. Heavily weighted silk may not wear as long as pure unweighted silk, because sunlight and perspiration weaken or destroy the fibers. Furthermore, heavy weighting causes silk to crack. The long treatment of silk in the weighting process may also have a weakening effect on the fibers. Silk containing no metallic weighting is called "pure silk."