A metal, chrome-, or aluminum-plated roller found in the dampening system of a printing press used in offset lithography. In an intermittent-flow dampening system, the fountain pan roller rotates at a set rate in the water pan where it picks up a film of fountain solution on its surface. An alternating ductor roller contacts the fountain pan roller, picks up a quantity of fountain solution, then separates from the fountain pan roller to contact an oscillator roller. The amount of dampening solution sent to the ductor roller can be adjusted by controlling the rate at which the fountain pan roller turns (the faster it turns, the more of its surface is coated with the fountain solution), the length of time the ductor roller spends in contact with the fountain pan roller (the longer the two are in contact, the more of the surface of the ductor roller that is covered with solution), or by adding water stops. In continuous-flow dampening systems, the fountain pan roller is replaced with a metering roller, which is in constant contact with a transfer roller. (See Dampening System.)
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