A series of screws found in the ink fountain on a printing press used in offset lithography. The fountain keys, which can either be hand-turned or motor-driven, adjust the gap that exists between the fountain blade and the fountain roller. The width of this gap determines how much ink is allowed to pass from the fountain to the rest of the inking system. The fountain keys are lined up in a series across the width of the ink fountain, and can be adjusted one by one, depending on which portions of the plate require more or less ink. A plate that needs additional ink in its center requires that the fountain keys in the center of the fountain be loosened, for example. Resetting fountain keys should be done carefully, and typically moving from the center to the edges, to avoid mechanical warping or other distortion of the fountain blade. (See Inking System: Offset Lithography and Offset Lithography.)
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