Filter Paper and Paperboard, Uncoated, in Rolls or Sheets

Filter paper is characterized by a controlled, uniform pore structure designed to separate solids from liquids or gases. For classification under 4805400000, the paper must be specifically manufactured for filtration use — not merely absorbent or porous incidentally. Mill specifications showing pore size, filtration efficiency ratings, or flow-rate data are the most persuasive documentation for supporting this classification against alternative headings for absorbent or tissue papers.

Chapter 48 structurally separates kraft paper and paperboard into their own headings (48.04) based on the kraft pulping process, regardless of the paper's end use. A filter paper made from kraft pulp would therefore be evaluated under heading 48.04 rather than here. The exclusion in 4805400000 ('ex kraft') means importers must confirm the pulping process — sulfite, mechanical, or other non-kraft methods — to correctly place filter paper under this subheading.