A minimum of five specimens of each fiber sample having width x length (W x L) of 0.5 x 6.0 inch (12.7 x 152.4 mm) were cut from bulk fiber. Specimens were held at one end in a horizontal position and tilted at 45° with marks at 1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 inch from the free end. A flame was applied to the free end of the specimen for 30 seconds or until the flame front reached the 1 inch mark. If combus­tion continued, the duration was timed between each 0.5-inch mark. A thin metallic wire was inserted to support the specimen.

For the composite samples, five specimens having WxL of 0.5×6.0 inch (12.7×152.4 mm) were cut from the 3 mm thick composite plaque. Specimens were held at one end in a horizontal position and tilted at 45° with marks at 1, 2.0, 3.0, 4.0, 5.0 inch from the free end. A flame was applied to the free end of the specimen for 30 seconds or until the flame front reached the 1 inch mark. If combustion con­tinued, the duration was timed between each 1.0-inch mark.

11.3.4 VERTICAL BURNING TEST (VC-2)

A Govmark VC-2 chamber was used to conduct burning tests for some composites. This chamber is widely cited through out the USA and internationally to measure the ignition resistant properties of aircraft and transportation materials, tents and protective clothing.

For phenol formaldehyde composite samples, three specimens having width x length (WxL) of 3×12 inch (76.2×304.8 mm) were cut from the 3 mm thick compos­ite plaque. Specimens were held at one end in the vertical position. The flame was applied for 60 seconds and then removed until flaming stopped. The combustion time and burning length was recorded. If the specimen has burning length and burn­ing time less than 8 inch and 15 seconds, respectively, it is considered to be passed the standard (self-extinguished) Each separate set of specimens prepared for testing will consist of at least three specimens (multiple places).