|1. Metering roller sensitivity. Alcohol substitutes sometimes cause the metering roller to become sensitive to ink. The ink is first picked up by the chrome roller and then distributed to the metering roller. Mix one ounce of phosphoric acid with thirty-two ounces of gum and use this solution to re-etch the chrome roller. Re-etching should restore the water-receptiveness of the metering roller.
2. Banding relating to a hard metering roller. Banding can occur when using an alcohol substitute with a metering roller of normal durometer (25-30). The water banding on the roller results in very fine light and dark streaks around the cylinder and on the print. The solution is to use softer metering rollers.
3. Maintaining proper dampening solution concentration. Since the water in the dampening solution evaporates but most alcohol substitutes do not, the substitute concentration can increase significantly with time. For some substitute solutions, this causes significant problems with ink/water balance, ink lay, and even coating adhesion. Since substitute concentration cannot be easily determined, the system must be drained and wiped at least once a week.
4. Overcooling the dampening solution. Overcooling the dampening solution makes the ink very tacky and can lead to picking and piling problems. The best temperature setting for the refrigeration unit for dampening solution is 50 – 55 F, although it is normal for the temperature to increase slightly in the fountain pan.
5. Roller stripping. Roller stripping sometimes occurs when the inking system is not thoroughly cleaned between uses of different alcohol substitutes. When stripping occurs, the common procedure of copperizing the inking rollers on older presses, presses equipped with nylon or Teflon covered oscillator rollers, flushing the ink rollers with white vinegar and warm water ( after the ink has been removed with solvent) may correct the problem.
6. Plugging. Plugging of halftone shadows or small reverse type sometimes results if there is too little alcohol substitute.
7. Deposit on metering roller. Some dampening solutions tend to cause a deposit of white materials (salts) to build up on the metering roller. These white deposits can become sensitive and take on ink. The buildup usually occurs when the press stands idle overnight. To overcome this, the metering roller should be backed away from the chrome roller and washed with the proper cleaning solutions to clean and desensitize the metering roller.