How Can I Tell If a Tube Is Teflon?

Teflon is a trade name for the solid thermoplastic that has the chemical name polytetrafluoroethylene (PTFE). It is a polymer, as the name suggests, built from single-bonded tetrafluroethethylene units (monomers), containing only the elements carbon and fluorine. PTFE has several remarkable properties that serve in numerous applications: lubricants, dielectrics, joints and seals, piping and non-stick cooking utensils, to name a few.

Usually it is possible to identify an unknown plastic by performing a series of simple tests.

• 1

  Grip the tube at both ends and apply outward, pulling force sufficient to stretch it. If it will not stretch, or if it stretches but fails to return to its original length when the force is released, go to step 2.

  If it stretches and returns to its original length when the force is released, the tube is made of an elastomer--it cannot be PTFE.

• 2

  Heat the soldering iron to 500 degrees F, with the aid of the thermometer, then press the iron into the tube. If the material remains rigid it is a "thermoset" plastic; it cannot be Teflon, a thermoplastic that would soften at 500 degrees F.

• 3

  Drop the tube in a glass of water. If it floats, it has a density less than water and cannot be Teflon; it is probably either polypropylene (PP) or polyethylene (PE).

• 4

  Dry the tube. Ignite the lighter and hold the flame to an end of the tube. If it begins to burn with a flame it is not a fluoropolymer (containing fluorine), and therefore cannot be Teflon.

  Quench the flame immediately in the water.

• 5

  Hold a flame to the tube for several more seconds. If the material drips, it is not PTFE; it is probably chlorotrifluoroethylene (CTFE) or fluorinated ethylene propylene (FEP).

  PTFE will soften in a flame, but will not drip.

• 6

  Note the smell of the plastic, very briefly, by wafting the air toward you with your hand. If the odor seems to have an acrid or acidic quality, then it is probably a polyvinyl plastic (PVF).

  If it smells like burnt hair, then very likely it is PTFE.