Subheading 370710 covers emulsions that are applied to a base material to create light-sensitive media — the emulsion is the active coating used in manufacturing photographic plates, film, or paper. Subheading 370790 covers all other photographic chemical preparations, including processing solutions (developers, fixers, toners) that act on already-sensitized media after exposure. The function in the photographic process — coating versus processing — is the key distinction.

Many photographic processing chemicals contain regulated substances subject to EPA reporting requirements under TSCA, and some silver-bearing waste streams from processing have hazardous-material handling implications. Importers should verify whether specific formulations require TSCA certification at entry and consult a licensed customs broker or environmental compliance counsel for shipments containing restricted chemical constituents.