Basic knowledge of fountain solution (water bucket)

Basic knowledge of fountain solution (water bucket)

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.The main role of dampening solution:

- Cover the blank part of the plate with a thin and even water film to prevent the ink from spreading to the blank

- Supplemental layout hydrophilic layer

- Control the layout temperature to prevent the machine from overheating and the ink is too thin

· Currently common dampening methods:

- water velvet cover

- alcohol (ethanol or isopropanol)

- minus alcohol

- alcohol free

· Alcohol fountain solution:

1. dampening solution additive (usually <5%) + alcohol (recommended 10%-15%) + water

2. The role of alcohol

- Alcohol is a kind of surface active substance, which can reduce the surface tension of dampening solution, which is beneficial to the dampening solution and the printing plate. At the same time, it can reduce the amount of dampening solution; it evaporates quickly, takes away a lot of heat, and reduces the plate temperature.

3. pH value of dampening solution - acidity and alkalinity

- Recommended between 4.8-5.5, slightly acidic

- too low, corrosive plates and machines, ink drying slows down

- Too high, causing ink emulsification, dirty on the plate, destroying the graphic part of the plate

4. Conductivity of dampening solution - conductivity of dampening solution, affinity with printing plate

· Ink balance control (excessive moisture):

-The ink color of the print is light, even if the amount of ink is increased, the ink color does not deepen in time.

-The amount of ink accumulated in the ink roller increases, and the ink particles become thicker.

-The water on the front and back of the printed sheet is uneven, the paper is curled, and it is not easy to register.

- The surface of the ink film retains too much moisture, and the ink shovel has water drops when the ink is squeegee. The ink added to the ink fountain is not easily stirred evenly, and the transfer roller slips.

- There is moisture sticking at the tip of the blanket, and there are drops of water on both ends of the roller.

- Before and after the interruption of printing, the ink color contrast is large

- The layout is not dry after the shutdown