Common Issues in Plate Making and Solutions

Posted on 05-17-2024 by

Common Issues:

In addition to blurred images and dirty plates, common issues in plate making include:

1. Shallow Images:
    .Causes:
       .Overexposure.
       .Overdevelopment.
       .Insufficient density of the plate-making film.
       .Coarse plate surface texture, making dots easily damaged.

2. Disappearing or Shrinking Images/Dots:

    .Causes:
       .Long exposure time.
       .Negative exposure used for dot plates in overall composition.
       .Low density around certain film texts or dots, causing images to shrink after exposure.
       .Inconsistent thickness of the PS plate coating.

3. Enlarged Dots:

    .Causes:
       .Underexposure.
       .Underdevelopment.

4. Abnormal Plate Color:

    .Causes:
       .Plates stored for too long.
       .Plates exposed to strong light after development.

5. Abnormal Color after Baking:

    .Causes:
       .Insufficient or excessive baking time.

6. Abnormal Plate Base Color:

    .Causes:
       .Unqualified plate base.

Solutions:

 1. Shallow Images:

       .Printing factories can use ladder scales or signal strips to determine the exposure time.
       .Different PS plates require different development times and conditions; follow the manufacturer's formula.
       .Choose plates with fine, sharp textures that are less likely to be damaged during development.
       .Disappearing or Shrinking Images/Dots:

2. Determine the exposure time correctly, using the same batch of PS plates for testing and ensuring stable lighting during exposure.
    .Avoid using negative exposure for dot plates.
    .Pay attention to the issue of frayed edges around text and dots in films from older laser phototypesetters.
    .When selecting plates, ensure surface quality is good, with even coating and normal color.

3. Enlarged Dots:

       .Set exposure time based on plate conditions and consider any variable factors.
       .Understand the type of developer, its usage, temperature conditions, and other factors that may change after development. For instance, low temperatures in winter can reduce the developer's temperature.

4. Abnormal Plate Color:

       .Avoid using plates on dot or print products if they have been stored for too long and the quality is poor; replace the plate if necessary.
       .After development, store plates in a dark place or apply black ink to protect them from light.

5. Abnormal Color after Baking:

       .Pay attention to temperature and time during baking. Generally, bake at a constant temperature of 230°C-250°C for 6-8 minutes. The plate surface should turn reddish-brown if baked correctly.

6. Abnormal Plate Base Color:

       .Pay attention to the quality of the plate base, especially with recycled PS bases. Some may have unqualified metal components, and others may show fluorescent colors after development, indicating low durability. Such plates should be avoided to prevent affecting print quality.