Kapok finds use in bedding and upholstery industries, in the production of life-saving equipment, and in the construction of thermally insulated and soundproof covers and walls. On account of its buoyancy, freedom from water-logging and weight-bearing capacity, it is the material par excellence for the manufacture of lifebuoys and belts, waistcoats and other naval life-saving appliances. The buoyancy of kapok is about five times as great as that of cork and about three times that of reindeer hair. During the war, kapok was employed for insulating tanks, for lining aviation suits, for filling floats of army assault-bridges, and generally for replacing cork wherever lightness, moisture-resistance and floating power were needed.
The kapok fiber once used in floatation vests and has been used as building insulation has a hollow fiber and looks like glass fiber under the microscope. The hollow fiber has air inside allowing combustion deep inside the material. Smoldering fire and open flame travel quickly within the material.