The critical factor is whether the article is designed to withstand high industrial temperatures (refractory) or is intended for ordinary building construction. Refractory bricks are formulated with specific mineral compositions to resist furnace conditions; building bricks under 6904 are standard construction materials not engineered for extreme heat resistance. Composition, density, and the manufacturer's intended application all inform the classification.

Antidumping and countervailing duty orders have historically applied to certain ceramic bricks from specific origins. Importers should check current CBP and Commerce Department order lists for the applicable 10-digit tariff line and country of origin before filing entry, as orders can be added, modified, or revoked.