Glassine achieves transparency and low porosity through supercalendering of the base sheet — no surface coating is applied. Papers that achieve transparency through a coating or impregnating agent would fall outside heading 4806 and into coated-paper headings. Importers should retain mill process documentation confirming the absence of surface coatings when classifying borderline products.

Glassine used as a release liner base is a purely industrial substrate and does not trigger food, drug, or agricultural admissibility review at entry. However, if the glassine is further processed with a silicone or other release coating before importation, the finished product may classify under a different HTS heading. Importers should confirm whether the product is imported as base glassine or as a finished coated release liner, as the classification and applicable duty rate differ.