Question: I saw a fire extinguisher that...

Question: I saw a fire extinguisher that said it contained “light water.” What is light water and why is it used in a fire extinguisher?

Answer: Light Water is not an unusual form of water, but a trademarked fire-fighting agent produced by 3M Co. A combination of glycols, detergents and surfactants dissolved in water, it produces a foam when the extinguisher is operated. The foam floats on the surface of a burning liquid--hence the name “Light Water”--limiting evaporation and blocking the supply of oxygen. The surfactants also help the water penetrate into deep-seated or hard-to-wet fires that can occur with interior furnishings, compacted paper, heavy beams, rubber tires, coal, hay or cotton.