SEPTEMBER/OCTOBER 2017 31 BULLE TIN NO. 761 By DLI's Education Department The Burn Test TECHNICAL OPERATINGInformation The Textile Fiber Product Identification Act requires textile product manufacturers to provide consumers with the generic name of the fiber, the percent of each fiber present, where the textile product was processed or manufactured, and the manufacturer’s registered name or number for each item. These labels only need to remain attached until the textile product is delivered to the consumer. Often, fiber content information is needed to determine the best process for an item. There are several methods used by textile technologists to identify fibers in a fabric. These methods include using the burn test, microscopic examina- tion, testing the solubility of fibers in various reagents, or staining fibers using dyes or reagents. The burn test is a helpful and simple test which can be used when no fiber content labeling is available. With this test, fibers can also be identified through the smell of the smoke they give off, and by the ash or melted bead that remains after burning. This test does not identify fibers specifically. It will indicate general fiber groupings such as cellulose, protein, mineral, and synthetic. This will help to determine appropriate care procedures and precautions. Limitations As stated, burn testing helps determine specific fiber groupings. Identification, however, can become even more difficult when a fabric or yarn is a blend of two or more fibers. Chemical finishes such as sizings or stain repellents may alter the burning properties of the fabric. For example, a flame retardant finish on a cotton fabric changes the flammability of the fabric. Also, the presence of some finishes may alter or mask the typical fume odor. When burn testing, follow these procedures: • Clip a small sample from an interior or unexposed/ hidden seam of the garment or item. • If necessary, such as with a blended fabric or yarn, unravel the sample fabric to test the yarns in each direction. Test each set of yarns separately. • Hold the yarns or small piece of fabric with tweezers. • Bring a flame just to the edge of the sample, without mak- ing direct contact. Observe how the yarn or fabric reacts. Synthetic fabrics may begin to curl or melt at this point. • Keep bringing the fabric closer to the flame until the fabric sample ignites. • Remove the fabric from the flame. • When the sample stops burning, smell the smoke. (You may need to blow the flame out with cellulose fibers). The three things to observe are: • How does it burn? (Does it burn rapidly? Does the flame go out quickly? Does it smolder? Does it melt?) • How does it smell when the flame goes out? • What does the residue/ash look like? (Is it hard or soft? Brittle? Fluffy?) A soft grey ash forms after burning a cotton sample. Many synthetic fibers form a hard, melted bead when burning.