Keep the same amount of ink in the ink fountain by adding small amounts of ink frequently. Lithographic ink is thixotropic--it does not flow unless worked and does not replenish the ink used by the pan roller. The amount of ink in the fountain pan roller gap affects the ink feed as the weight of the ink pushes the ink through the fountain gap. As the amount of ink decreases against the ink fountain pan roller, the ink feed through the fountain gap slows causing the operator to increase the speed of the ink fountain pan roller. When fresh ink is eventually added, the sudden increase restores the feed to a higher flow and the press experiences a rise in solid ink density. This solid ink density shift is most noticeable on forms with heavy ink coverage. Use an ink agitator or manually keep pushing the ink against the fountain roller with an ink knife, adding fresh ink as needed. An automatic ink pump/replenishing system is useful to keep the same amount of ink against the pan roller.