Vegetable parchment is produced by passing paper through a sulfuric acid bath, which gelatinizes the surface fibers to create a dense, grease- and moisture-resistant sheet. Greaseproof paper achieves its barrier properties through intensive beating of the pulp and supercalendering, without acid treatment. The manufacturing process — not just the end-use barrier performance — determines which subheading applies.

Silicone-coated release liners are typically classified outside 4806 because the silicone coating constitutes a surface treatment that moves the product into the coated-paper headings elsewhere in Chapter 48. Glassine used as a release-liner base stock before coating may enter under 480640, but once coated it generally reclassifies. The nature and extent of the coating is the controlling factor.