Control of leachable mercury in fluorescent lamps

This invention relates to mercury vapor discharge lamps and more particularly to fluorescent lamps. Still more particularly it relates to lamps that can be landfilled without leaching potentially damaging mercury into the environment. A method for inhibiting the leaching of mercury from a mercury vapor discharge lamp wherein at least a part of the mercury is present as ionic mercury includes depositing a coating of SnOon an interior surface of the lamp envelope. The SnOcoating is substantially free of a substance which would cause electrical conductivity of the coating. Further included within the lamp is a quantity of oxidizable iron in an amount equal to at least 1 gram per kilogram of lamp weight.