Zinc dust (790310) is produced by vapor condensation and consists of very fine, roughly spherical particles. Zinc powders and flakes (790390) are made by mechanical processes such as milling or stamping. The distinction matters for duty purposes, and the supplier's production method documentation supports correct classification.

Importers should check whether specific origin-country combinations are subject to antidumping or countervailing duty orders, as these can apply at the tariff-line level. Consulting the relevant CBP and Commerce Department orders for the specific subheading and country of origin is advisable before entry.