Vapo-Lock Encapsulating Agent works at the molecular level to form bonds around hydrocarbons, rendering liquids and vapors inert. It rapidly dissolves hydrocarbon sludge and residue, reducing the concentration of hydrocarbon vapors below their Lower Explosive Limit (LEL). Vapo-Lock quickly and safely returns the tank for inspections, repairs or general clean-out. It can be safely applied to all stainless steel, aluminum, or carbon steel tanks without harm. After a wash-out & rinse, Vapo-Lock does not leave a residue.