Tall oil is explicitly excluded from 3804 and classified separately. Residual lyes under 3804 are the aqueous byproduct streams from pulping — primarily lignin sulfonates from sulfite processes — whereas tall oil is the fatty-acid-rich fraction skimmed from kraft black liquor. The exclusion is stated in the heading text itself.

Concrete admixture manufacturers use lignin sulfonates as water-reducing plasticizers; animal feed producers use them as pellet binders; and mining and road-construction companies use them for dust suppression. The same chemical can serve multiple industries, so end-use declarations may be relevant for certain duty drawback or downstream processing programs.