Mixtures of Natural and Synthetic Rubber

The HTS does not specify a minimum natural rubber content threshold; classification as a mixture under heading 4002 depends on whether the product is a deliberate blend of natural rubber (heading 4001) with synthetic rubber (heading 4002) or factice. A product that is predominantly synthetic rubber with only incidental natural rubber content may still classify as a pure synthetic rubber. Importers should document the formulation and consult a licensed customs broker or seek a binding ruling when the blend ratio is near a classification boundary.

Factice is a rubber-like material produced by treating vegetable or animal oils with sulfur or sulfur chloride. When blended with natural or synthetic rubber, the resulting mixture still classifies under heading 4002 (specifically 4002800000) provided it meets the general definition of a rubber mixture in that heading. Factice alone, without rubber, classifies elsewhere, so the presence and proportion of factice relative to rubber content should be clearly stated in product documentation.