Steel wool

[2] Steel wool is commonly used by woodworkers, metal craftsmen, and jewelers to clean and smooth working surfaces and give them shine.

Steel wool is often used for professional cleaning processes on glass and porcelain because it is softer than those materials and is able to scrape off deposits without scratching the underlying surface like common abrasives.

Small holes are plugged with coarse grade steel wool, which, if gnawed on by rodents, causes extreme pain in the mouth and, if ingested, severe internal damage may lead to death.

When steel wool is heated or allowed to rust, it increases in mass due to the combination of oxygen with iron.

Very fine steel wool can also be used as tinder in emergency situations, as it burns even when wet and can be ignited by fire, a spark, or by connecting a battery to produce joule heating.