Decrease in Tone Value |
 |
What is it?
The reduction of the halftone dot in the print when compared to the original (film orprinting plate) is referred to as a decrease in tone value. In essence – abrasion of the printing plate.
How does it happen?
This phenomenon may already arise in prepress. In addition, various factors can also have a bearing on abrasion of the printing plate:
- Normal plate wear and tear
- Powder deposits on the blanket
- Unsuitable plate cleanser (a mixture of abrasive material)
- A pH-value in the dampening solution that is too low may slightly etch the edges of the halftone dots
- An alcohol content that is too high corrodes the plate film
- Rapidly volatizing cleansing solutions may damage the printing plate
Remedy:
- Use appropriate printing plates
- Use a suitable plate cleanser and certified cleaning solution when maintaining the printing plate
- Avoid using abrasive spray powder (calcium carbonate) use a based starch powder such as Superdot
- Always prepare dampening solution according to instructions (pH-value, alcohol concentration); the ideal dampening solution has a water hardness of 8 to 12°dH, a pH-value of 4.8 to 5.5, and a temperature ranging from 10°C to 15°C (50°F to 59°F)
|
|
|
|
|
|
|
|
|
 |
|
Tips & Tricks
Find out more Tips & Tricks here.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|