Which test is commonly used to identify natural and synthetic fibers in carpets?

The burn test is a well-established method used to identify the composition of fibers in carpets, distinguishing between natural and synthetic materials. When a small sample of fiber is subjected to an open flame, it will react differently depending on its chemical structure. For instance, natural fibers such as cotton and wool will burn and produce specific characteristics, such as ash or a particular smell, while synthetic fibers like polyester or nylon will melt, creating a bead-like residue.

This test is effective because it utilizes the distinctive combustion properties of each type of fiber to aid in identification. In contrast, other tests, like the colorfastness test, evaluate how well a carpet retains its color when exposed to various conditions, and are not focused on fiber identification. The density test measures the compactness of the fibers but does not provide insights into their composition, and the friction test assesses the wear resistance of carpets, which is also unrelated to fiber identification. Thus, the burn test stands out as a reliable and straightforward method in the context of determining whether fibers are natural or synthetic.