Gelling agents are chemicals that, when added to oil, solidify the oil to create a rubber-like substance. Gelling agents are used to contain oil spills, as the rubberized material is easier to separate from water than oil. They can also be used for ground spills.
Gelling agents self-mix when applied to smaller oil spills, but larger spills must be mixed using high-pressure water streams to mix the agents thoroughly. The ratio of gelling agent to oil required for effectiveness is generally three parts agent to one part oil. Because of the large amount of gelling agent needed compared to the amount of oil, the agent cannot be applied to extremely large spills with volumes in the millions of gallons.