Causes and Solutions for Irregular Small Dots After Plate Baking

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In offset printing, even a seemingly clean plate can develop small, irregular dirty spots after baking. These defects often remain invisible until the plate is mounted on the press, which can affect print quality and waste materials. Understanding the main causes and applying proper solutions can help maintain consistent results.

Common Causes and Solutions

1. Excessive Washing Pressure or Uneven Coating
High washing pressure may cause water droplets to splash onto the plate, resulting in uneven baking gum application and tiny spots.
Solution: Reduce washing pressure and ensure the plate surface is completely dry before applying the gum.

2. No Baking Gum or Protective Layer
Without a protective coating, oxidation or dust can form during high-temperature baking.
Solution: Always apply a uniform layer of baking gum or protective solution before baking.

3. Incorrect Baking Temperature or Duration
Overheating or prolonged baking can damage the plate surface, causing stains.
Solution: Maintain a temperature around 220°C for less than 5 minutes, adjusting according to the plate type.

4. Uneven Application of Baking Gum
Uneven gum thickness can result in inconsistent heating and small dirty spots.
Solution: Smooth the gum evenly with a blade after application.

Even minor imperfections can impact the quality of book printing. By carefully controlling washing, coating, and baking procedures, printers can achieve cleaner plates and sharper prints.

For professional printing tips, techniques, and high-quality custom solutions, visit printing in China.

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