Tow (Fibre): The Coarse Combed-Out Flax and Hemp Fibre

**Tow** is the short, coarse, tangled fibre combed out of flax or hemp during processing — as distinct from *line* fibre, the long, aligned, high-value strands that go on to be spun into linen yarn. ## Where it comes from Bast fibres are extracted from the stem in stages. Retting rots away the pectins binding fibre to the woody core. Breaking and scutching crush and beat off the woody shive. Heckling then draws the fibre through progressively finer combs, which aligns the long strands and pulls out everything short or tangled. What the combs pull out is tow. It is a by-product by definition, and cheaper than line fibre for that reason. The name is literal in more than one language: oakum comes from Old English *ācumba*, "off-combings", and Russian пакля names the same combed-out product. See Plumber's Hemp, Flax Tow, Oakum, Пакля: The Same Material Under Many Names. ## What it is used for - **Caulking ship seams.** Tow — traditionally picked from old tarred hemp rope, which is where the tarred form takes the name oakum — was driven into the seams between hull planks and payed with pitch. Picking oakum from old rope by hand was the archetypal Victorian workhouse and prison labour task. - **Sealing threaded pipe joints**, wound with a paste. See Sealing Pipe Threads with Flax Tow and Jointing Paste. - **Chinking log buildings** — packed between logs as an insulating, air-sealing filler. - **Coarse yarn, rope, sacking, and paper stock**, wherever fibre length is not critical. ## Why it suits sealing work The properties that make tow a low-grade textile make it a good gap filler. It is bulk material rather than a film or sheet, so it conforms to irregular geometry. Flax fibre swells appreciably when it absorbs water, so a packed joint tightens as it wets. And it is cheap enough to use in quantity. Its weakness is equally straightforward: it is organic, so unprotected fibre in a damp joint rots — which is why the paste in a pipe joint is a preservative as much as a sealant, and why organic fibre sits awkwardly with drinking-water material rules: Hemp Thread Sealing and Drinking Water: Approved in Germany, Banned in the UK.