NCIDQ IDFX Practice Exam

What fabric continues to burn even after removal from flame?

1. Cotton

2. Polyester

3. Wool

4. Nylon

The correct answer is: Cotton

Cotton is known to have a high rate of flammability and, importantly, it tends to continue burning even after the source of the flame has been removed. This is a characteristic of natural fibers, particularly cellulose-based ones like cotton. The composition of cotton allows it to sustain combustion under certain conditions, leading to the potential for it to continue smoldering or even burning until all of the oxygen is consumed or the material is fully charred. In contrast, fibers such as polyester, wool, or nylon exhibit different flame-retardant properties. For instance, polyester and nylon are synthetic fibers that tend to melt rather than continue burning when a flame is removed, which can sometimes aid in preventing further combustion. Wool, being a protein-based fiber, is naturally more flame-resistant and often self-extinguishes when the flame source is removed due to its ability to absorb moisture and its high nitrogen content. Understanding the combustion characteristics of different textiles is crucial for selecting appropriate materials for various applications, particularly in interior design and furnishings where fire safety is a concern.