Heading 8311 applies specifically to wire and rods that incorporate flux or filler material — either as a core inside the wire or as a coating on the outside. Bare wire without any flux or filler classifies under the wire headings of the relevant base metal chapter (e.g., Chapter 72 for steel wire), not under 8311.

Brazing rods and soldering materials that have a base metal substrate with flux — even if they contain silver or other precious-metal alloys as part of the filler composition — generally classify under 831130 based on their function as soldering or brazing consumables. However, if the precious-metal content is dominant and the article is primarily a precious-metal product, classification may shift; consult a licensed customs broker for high-silver-content alloys.