How dental floss is made

Nylon replaced silk in floss during World War II because it resisted abrasion better and came in great lengths.

stations: 7
things upstream: 35
raw sources: 12
steps from the ground: 6

The short version

Nylon floss starts as polymer poured out in a ribbon and chopped to chips, which are remelted and pumped through spinnerets into filaments. The filaments gather into yarn and are twisted 2.5 to 3.5 turns an inch, which stops fraying. Baths add wax and flavor. It is wound on bobbins, usually placed in cases by hand and threaded around a metal cutter.

Chop the polymer

Nylon salt polymerizes and pours out as a ribbon, which is cut into chips, flakes or pellets and blended.

Goes in
Nylon
Spin the filaments

Remelted chips are pumped through spinnerets. As the fine streams cool they solidify and regather into a yarn.
Twist the strand

The ends of the filaments combine into one strand with 2.5 to 3.5 turns per inch. That twist adds strength and greatly cuts fraying and breaking. PTFE floss skips this as a single stretched filament.
Pull through coating baths

The strand runs through emulsion baths of wax, flavor and other coatings at a steady speed. Patents add drying heat so the coating holds the floss in shape.

Goes in
Paraffin wax
Wind the bobbins

The coated strand is wound in cylindrical or roll-shaped bobbins. Cylindrical ones hold more yardage.
Mold the case

The common case is an angled two-piece polypropylene shell with an insert to hold the spool. Some newer ones are one-piece clamshells with a window.

Goes in
Polypropylene
Assemble by hand

Workers usually cut bobbins apart and place them in the container, thread the floss around a metal cutting clip, and close the cover.

Goes in
Steel

End of the lineDental floss

Worth repeating

Levi Spear Parmly, a New Orleans dentist, recommended running waxed silk thread between the teeth in 1819.
Johnson & Johnson received the first patent for dental floss in 1898, using the same silk doctors used for stitches.
Nylon floss was developed during the war by the physician Charles C. Bass.