The IMO A.471 certification is the International Maritime Organization’s criteria for the flame resistance of vertically supported textiles and films, including curtains, draperies, and other free-hanging fabric. Certification can also be done through IMO A.563.
The scope of testing involves subjecting a vertically oriented test specimen to a small flame along the lower portion of the material. The test is repeated five times along both the warp and weft. After the specimens are extinguished, a minimum of ten samples—five burned along the weft, and five burned along the warp—are examined. Products are deemed unsuitable if they are observed with any of the following characteristics:
- An afterflame that continues for more than five seconds
- Burns from the center to any edge of the specimen
- Ignition of cotton wool placed below the specimen
- An average char length that exceeds 150 mm
- Even without charring the material, if a surface flash that exceeds 100 mm from the point of ignition is observed
If any of the samples are found to have the above characteristics, the product does not pass certification.