To synthesize transparent and homogenous sol-gel solutions for the fabric coating, the amounts of reactants and reaction conditions were carefully chosen according to the recommendations from the previous studies. The precursors OTES and GPTMS were used because this silane system can provide fabric with a soft handle after coating. Once coated, a transparent and well-attached silica coating layer was formed on the wool fabric. The amount of silica coating pickup on the fabric is given in Table 1.