Spray tanning involves applying DHA, or dihydroxyacetone, to the skin using an air mist delivery system. DHA interacts with amino acids in the skin to produce the golden brown color.
Most spray tan solutions contain a bronzer that gives instant color once it is applied to the skin. The bronzer will wash away after your first rinse and will have no affect on your tan. The amount of DHA in a solution is what creates a darker tan, not the amount of bronzer. DHA is approved for cosmetic application by the FDA.