1. Water spots. According to the principle of oil-water incompatibility, if there are water droplets on the paper, a water spot will be left on the print. Cause analysis:Analysis On The Aauses Of Printing Dirty

(1) If the air pump is in the environment of high temperature and humidity, and the offset press is placed in the air-conditioning workshop, the moisture in the humid air will be blown to the cool environment through the air pump, and the salty water droplets will be condensed and blown to the paper through the presser foot and paper separation nozzle.Analysis On The Aauses Of Printing Dirty

(2) The bucket of many offset presses is made of iron sheet or copper-plated iron sheet. Because the acidic wetting solution is corrosive, over time, the bucket will be gradually corroded to form sand holes. Analysis On The Aauses Of Printing Dirty

      Some sand holes are very small and can only drop two or three drops of water a minute. In this way, there will be occasional water spots on the prints. Therefore, the operator needs to carefully check the water bucket against the light and solder it firmly with tin if sand holes are found.Analysis On The Aauses Of Printing Dirty

(3) The maintenance of some offset presses is not perfect, and the operators never clean the water bucket. In addition, when cleaning the ink roller, the ink on the ink roller splashes everywhere with the cleaning agent, and the ink thrown into the water bucket forms scale together with the fluff of the water roller. Analysis On The Aauses Of Printing Dirty

      With the rotation of the water bucket roller, it accumulates between the water bucket roller and the water bucket wall, forming hard slag over time.Analysis On The Aauses Of Printing Dirty

       When the bucket roll rotates, the hard slag will drip down the bucket wall from time to time with the water on the bucket roll, forming water spots on the print.Analysis On The Aauses Of Printing Dirty

(4) When the printing plate needs emergency water supply due to small water paste, the bucket roller will transfer a large amount of water to the water transfer roller, and the excess water will drip down during the transmission and extrusion of the water transfer roller A water baffle is installed under the water bucket of J2108 machine,Analysis On The Aauses Of Printing Dirty

       which has a good effect, but it is necessary to avoid dripping due to too much water. J4104 and other models do not have water baffle, so there should be enough for emergency water supply.Analysis On The Aauses Of Printing Dirty