Classification Mechanics for Pure Linen Woven Fabrics under Heading 5309
Classification under HS Heading 5309 requires verifying an 85% clean dry flax mass fraction after stripping non-cellulosic sizing and applying standard regain.
Pure Flax Fabric
Fiber Composition
Woven textiles constructed entirely from bast fibres harvested from Linum usitatissimum comply with strict unblended material classifications. Quality verification agencies certify woven goods as pure flax fabric only when microscopic fiber identification confirms absolute absence of secondary natural or synthetic fibers. Warp and weft yarn systems must contain one hundred percent flax structures without core-spun synthetic filaments.
Official inspection certificates state total cellulosic purity based on quantitative lab analysis.
Loom Specification
Fabric construction employs either long line wet-spun yarns or dry-spun tow yarns across warp and weft directions. Producing pure flax fabric requires dedicated weaving equipment free from cotton or synthetic lint contamination during beam preparation and weaving. Weavers adjust loom tension and relative humidity in weaving sheds to accommodate the low elasticity of pure flax yarns under shuttle movement.
Finishing processes like bleaching, dyeing, or mechanical softening alter fabric handle without compromising pure fiber composition. Quality control laboratories test sample swatches for structural integrity and chemical purity.
Labeling Rule
Pure material designations do not cover textiles containing decorative selvedge threads made from non-flax materials unless disclosed on trade documentation. Fabric containing even fractional percentages of viscose, cotton, or polyester must be sold under blended textile trade headings.