Various structures are disclosed to provide flat fluorescent lamps adapted to provide improved optical characteristics by reducing sodium elution from one or more glass plates. Related methods of manufacture are also provided. In one example, a flat fluorescent lamp includes a first plate and a second plate adapted to form a plurality of discharge chambers in combination with the first plate. A first elution preventive layer is provided on an inner surface of the second plate. A first fluorescent layer is provided above an inner surface of the first plate. A second fluorescent layer is provided above the first elution preventive layer. In another example, the first and second plates comprise sodalime glass. In another example, the elution preventive layer is adapted to prevent sodium eluted from the second plate from exceeding a predetermined sodium elution amount.