All three are mechanical processes that retain most of the wood's lignin, yielding high-bulk, opaque fiber suited for newsprint and magazine papers. TMP uses heat to soften fibers before refining, and CTMP adds a mild chemical pre-treatment, both improving strength over stone groundwood. For US customs purposes, all three classify under 4701000000 — the distinctions are commercial and affect pricing and end-use suitability, not the tariff line.

Woodpulp is typically traded and valued on an air-dry weight basis (approximately 90% dry content), and customs entries should reflect this convention. Importers should confirm whether the commercial invoice weight matches the air-dry standard or a bone-dry basis, as discrepancies can affect both valuation and any weight-based statistical reporting.