After like has been subjected to tin-weighting, it is thicker and heavier in feel and has higher draping quality than non-tin-weighted silk without losing its excellent character. Therefore, silk has popularly been weighted with stannic chloride from ancient times To establish the most effective tin-weighting method, we investigated several effects for tile tin-weighted silk : the concentration of tin : the pass number : dyeability of acid dyes : diffusion coefficients : load-extension behavior : fastness for laundering. The results of the experiments can be summarized as follows: 1. The most properly treated conditions of tin-weighting of silk are 37% of stannic chloride conc., 15~2$0^{circ}C$ of temperature, 1 hr of treatment time. 2. Degree crystallization has scarcely chanced with various conto. of stannic chloride bit three pass and over, decree of crystallization was nearly broken. 3. When silk was treated with 37% of stannic chloride. tensile strength and elongation have decreased by 11% and 14% respectively. decrease of 2 pass of 17% stannic chloride ronr. Hat less than 20%. 4. Between denier and various conc. of stannic chloride, denier was thicker 18% than non tin-weighted silk at 37% of stannic chloride conc., but decreased at conc. of 37% upward. 5. Relation between dye absorbed of C.1. Acid Blue 82 and C.1. Acid Blue 140 of 2% (o.w.f.) dye conc and various stannic chloride conc. and various pass No. on weighting silk have scarcely changed, but C.1. Acid Blue 140 was more effective than C.1. Acid Blue 92 in dyeing.