First special grade castor oil is produced by refining commercial grade castor oil by undergoing bleaching and filtering process. Bleaching is done using bleaching earth and activated carbon, which helps to reduce color and moisture content. It is light yellow viscous oil in appearance with colour max: 2.2 yellow & 0.3 (1"cell on lovibond scale), f.f.a : 1.00% max, m.i.v.: 0.25% max.