Pre-treating the chicken feathers in various concentrations of alkali at 90 °C for 30 min dissolved the feathers and provided keratin solution with viscosity of 1.5 mPas compared to 2 mPas for PVA. The viscosity of the keratin solution was considerably lower than that of chitosan (20–140 mPas) suggesting that higher concentrations of keratin solution could be used for sizing (Stegmaier et al., 2008).