Silicone sealants that function as caulking compounds or mastics — used to seal joints and gaps — generally fall under 321410. If a product is instead formulated as a nonrefractory surface coating applied to walls or floors for finishing purposes, it may fall under 321490. The product's primary function and formulation, as described in the heading text and any applicable chapter notes, govern the classification.

Yes — painters' fillings under 3214 are specifically used to prepare surfaces before painting (filling cracks and imperfections), whereas paints and varnishes in the adjacent chapter are applied as a final decorative or protective coat. If a product both fills and coats, its principal function and composition determine which heading applies; a binding ruling from CBP can resolve borderline cases.