Knowledge

Flame Retardancy



  • Cut two representative samples of your fabric or film, each rectangle approximately 1" wide by 5" long (ed. note: NFPA 705 calls for 1’ wide strips, but 2” wider yields a test that more closely approximates the lab results).

  • The long side of the first cut sample should be oriented with the vertical (height) of your fabric. The other sample should be oriented with the horizontal (width) of your fabric. In other words, the second rectangular piece is cut at a 90° angle to the first.

  • Find a safe place for testing-the space and floor must be clear of burnable materials, particularly draperies, fabrics, paper, wood and sawdust. Also find a place free of drafts.

  • Have a fire extinguisher close at hand, a source of water (sink), or a bucket of water.

  • Suspend each sample vertically, the short edge at the bottom. Metal tongs or pliers work well to keep fingers out of the test.

  • Using a standard, wooden kitchen match, apply the tip of the flame to the center of the bottom edge of the suspended sample. Maintain the flame steadily in the initial position beneath the edge of the fabric for 12 seconds. The position of the flame should not move up to stay in contact with the edge of the fabric as it burns away.

  • Only if no wooden match is available, use a lighter. Lighters burn at much hotter temperatures than wood, but we find that we get similar results no matter the flame source

  • All fabrics burn to some extent. You should expect some burning. As the sample burns or chars (blackens) or melts, the tip of your flame remains stationary- do not move up the flame you are holding, as the material burns or melts away. Your match simulates the fixed position of a Bunsen burner from the lab-it does not move during testing.

  • After 12 seconds, remove the match and blow it out well away from the specimen sample.

  • Continue to observe your specimen. Any flame on the specimen must self­ extinguish within 2 seconds after you remove the match. If any flame has extinguished before the removal of the match, even better.

  • Any glowing (afterglow) along the burnt edge of the fabric or any generation of smoke must stop completely within 20 seconds after the removal of the match.

  • If either of these limits is exceeded, your material is not sufficiently flame resistant to be safe. You need to re-treat or replace it with something better.

  • If your first specimen passes, then repeat this test for the second specimen.

  • Frequently, particularly with synthetics, you will find that one direction passes, but not the other. FR treatment or re-treatment or replacement is still in order, if only one specimen passes but not the other.


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