· The main function of fountain solution:
-Cover the blank part of the printing plate with a thin and uniform water film to prevent the ink from spreading to the blank part
ï¼Supplement the hydrophilic layer
ï¼Control the plate temperature to prevent the machine from overheating and the ink is too thin
· Common dampening methods:
ï¼Water wool cover
ï¼Alcohol (ethanol or isopropyl alcohol)
ï¼Alcohol reduction
ï¼Alcohol-free
· Alcohol fountain solution:
1. Fountain solution additive (usually <5%) + alcohol (recommended 10% -15%) + water
2. The role of alcohol
ï¼Alcohol is a surface active substance, which can reduce the surface tension of the fountain solution, which is conducive to the affinity of the fountain solution and the printing plate, and at the same time can reduce the amount of fountain solution; fast volatilization, take away a lot of heat, and reduce the temperature of the plate surface
3. pH value of fountain solution-acidity and alkalinity
ï¼Recommended between 4.8-5.5, acidic
ï¼Too low, corrodes the printing plate and machine, and the ink drying slows down
ï¼Too high, causing emulsification of ink, dirt on the plate surface, destroying the graphic part of the plate
4. The conductivity of the fountain solution-the conductivity of the fountain solution, the affinity with the printing plate
· Ink balance control (expression of excessive water):
ï¼The ink color of the printed matter is light, even if the ink volume is increased, the ink color will not deepen in time
ï¼The amount of ink stored in the ink roller increases, and the ink particles become thicker
ï¼The amount of water on the front and back of the printed sheet is uneven, the paper is curled, and it is not easy to register
-Excessive water retention on the surface of the ink film, water droplets when the ink shovel scrapes the ink, the ink added to the ink fountain is not easy to stir evenly, and the ink transfer roller slips
ï¼Moisture sticks to the trailing edge of the blanket, and water drops drip from both ends of the roller
ï¼Before and after the printing is interrupted, the contrast of the ink color of the printed matter is large
ï¼The layout is not dry after shutdown
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