Tall oil, also called "liquid
rosin" or
tallol, is a viscous yellow-black odorous liquid obtained as a
by-product of the
Kraft process of
wood pulp manufacture when pulping mainly
coniferous trees. The name originated as an anglicization of the
Swedish "tallolja" ("pine oil"). Tall oil is the third largest chemical by-product in a Kraft mill after
lignin and
hemicellulose; the yield of crude tall oil from the process is in the range of 30 – 50 kg / ton pulp. It may contribute to 1.0 - 1.5% of the mill's revenue if not used internally.