Why Steel Wool Burns But Steel Doesn’t Steel wool and solid steel are both primarily composed of iron, but their flammability differs due to physical structure. Steel wool consists of extremely fine filaments, dramatically increasing its surface-area-to-volume ratio. This allows for rapid oxidation, as more iron atoms are simultaneously exposed to oxygen. Additionally, the low thermal mass of each strand enables it to reach iron’s ignition temperature (~900°C) with minimal energy input, such as