Causes of bubble formation:

1. The surface tension of the ink is relatively high, making it greatly affected by the resins and solvents used in the ink. Sometimes, high ink viscosity also easily leads to bubble formation.

2. Defects in the ink tank or circulation device. A large number of bubbles are caused by poor ink flow in the ink tank or circulation pump. When using an ink pump to circulate ink, the ink flows from the ink tank into the circulation bucket. Due to the drop and the agitation caused by the high-speed rotation of the printing plate cylinder, bubbles will form in the ink.

3. On printing presses with direct ink supply, a bent magnetic ink stirring rod jumps around in the ink tank, causing bubbles.

4. Add an appropriate amount of defoamer. Specialized defoamers exist, but most have adverse effects on ink properties and improper use can actually cause bubbles, so they should not be used excessively.