"Roller powder", namely in the offset printing process, printing machine running a period of time, the roller appear powdery particulate matter, and ink deposition does not need areas (such as a roller) or roller inking ink transfer the bad phenomenon. This is mainly because the printing fault, powder particles on the ink rollers lipophilic or hydrophilic.

In the offset printing process, ink and water two substances are very important in the process of ink. The water fountain solution, ink is offset printing ink. Have a good transfer in water and ink only when printing prints can be fine. However, because the ink transfer is affected by many uncertain factors, making the ink control becomes a key problem in the most difficult to offset control. In the offset printing production process, there will be a variety of ink transfer fault, one fault is for roller sometimes powder, and lead to poor transfer of ink.

The fountain solution of water is the main ingredient in and around the water hardness is not the same, the general soft water total hardness is 0~30ppm and hard water total hardness in more than 60 ppm. When the quality of partial hard (i.e. ca+ content to be many), usually resulting in ca+ and printing ink resin contact to form calcium saponification, acid fountain solution acid contact with, will produce such as calcium citrate or calcium phosphate, calcium salt. Calcium saponification with lipophilic, will lead to ink deposition in the region do not need, the roller surface crystallization, transfer of water and ink undesirable phenomena; and calcium salt with a hydrophilic, will hinder the ink transfer and resulting in the ink roller inking. Therefore, fault solution is as much as possible to use soft water ca+ content is small to allocate or fountain solution dilution. At the same time, we should choose those can effectively reduce calcium deposition of the fountain solution to eliminate the influence caused by calcium ion.

In the offset printing process, mainly from the external continuously into the printing machine is the substrate material, ink and fountain solution. So these substances must be in powder particles by the three substances directly or indirectly zone.

In general, if the quality of the substrate surface is not good it is possible to powdery particulate matter directly into the printing ink system. Powder powder through for example, when the surface of the paper itself, with a lot of paper powder and other powder, the dirt with nano imprint lithography process printing plate is transferred to the ink transfer system, so as to lead to a "roller" fault occurs, the solution is by replacing the surface clean substrate for printing production; in addition, the paper surface itself is clean, but due to the paper surface coated tight enough in nano imprint lithography process off powder, hair loss, through the printing plate is transferred to the ink transfer system, the same will lead to a "roller" fault, this situation can reduce the speed, reduce the ink viscosity or replacement of better quality paper to solve.

In addition to the substrate directly to the powder particles into the printing system, the chemical reaction between the ink fountain solution and precipitation of calcium may occur, thus indirectly the powder particles into the printing system.