Standard International Trade Classification
U.S. exports of Unsaturated Polyesters, Primary Forms (N.E.S.) (SITC 57434) totaled $26.3M in August 2026.
Importers of Unsaturated Polyesters, Primary Forms (N.E.S.) paid $986K in duties in August 2026, an average duty rate of 6.12% — duty actually collected as a share of the imports that cleared customs, not the published tariff schedule. Unsaturated Polyesters, Primary Forms (N.E.S.) imports of $16.1M in August 2026 ran 11% above the year-to-date monthly average of $14.6M.
Last updated: August 2026 dataUnsaturated polyesters in primary forms — those not elsewhere specified — are reactive thermosetting resins that cure when combined with a monomer such as styrene, making them foundational materials for fiberglass-reinforced composites, marine hulls, automotive body panels, and construction laminates. The 'N.E.S.' designation means this code captures residual unsaturated polyester types not broken out under more specific headings such as alkyd resins or PET. Trade professionals should note that the reactive nature of these resins may trigger hazardous materials shipping regulations (IMDG/IATA) depending on inhibitor levels and peroxide content in the formulation. Proper safety data sheets and inhibitor certification are standard documentation requirements.
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425 import shipments a month
Because unsaturated polyester resins are often classified as flammable liquids or reactive materials under international transport regulations, importers typically need a current Safety Data Sheet (SDS), proper UN hazmat classification, and inhibitor concentration certification. Ocean shipments must comply with IMDG Code requirements, and air freight may be restricted depending on formulation.
The 'not elsewhere specified' qualifier means this code is a residual catch-all for unsaturated polyesters that do not meet the specific definitions of alkyds or other named polyester subheadings. Importers should first confirm the resin does not qualify under a more specific heading before defaulting to this code, as misclassification can affect duty liability and trade remedy exposure.
Basic heading 160 of 465 in section 5
Basic heading 57434 · $26.3M of $26.2B
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Exports · August 2026
destination
Canada and Mexico together take 90% of it.
customs district
Census does not publish district detail for this classification system.
origin
Census does not publish state detail for this classification system.
entry
Census does not publish port detail for this classification system.
ImportsExports
Imports
$16.1MYoY · free account
Exports
$26.3MYoY · free account
12-mo low · imports
Low · free accountOver the twelve months to August 2026, the U.S. imported $160.9M of Unsaturated Polyesters, Primary Forms (N.E.S.) and exported $283.7M.
Through August 2026. Source: U.S. Census Bureau.