What does a flame retardant do when applied to materials?

A flame retardant is a chemical substance that, when applied to materials, primarily functions to slow down or prevent the spread of fire. This capability is crucial in various applications, particularly in stagecraft and other environments where safety from fire hazards is paramount. By chemically altering the material's properties, flame retardants reduce the likelihood of ignition and help contain flames if a fire does occur.

Fire safety regulations often mandate the use of flame retardants in textiles, upholstery, and other materials used in public venues, ensuring that the risks associated with fire are minimized. This is especially important in stage production settings where multiple elements, including props, costumes, and scenery, may be in close proximity and subjected to heat or open flames.

In contrast, the other choices reflect characteristics that are not related to the primary function of flame retardants, such as increasing flammability or improving aesthetics, which do not contribute to safety. Similarly, waterproofing is not a function of flame retardants; it pertains to other treatments designed to repel water, highlighting the specific, safety-focused role that flame retardants play in material application.