Causes and Solutions for Irregular Small Dots After Plate Baking
Problem Description:
Before baking, the printing plate appears clean with almost no stains. However, after baking, many small and irregular dirty spots appear. These spots are often invisible to the naked eye until the plate is mounted on the press and printing begins.
Possible Causes and Solutions:
Excessive washing pressure or uneven coating Excessive pressure during plate washing can cause water droplets to splash onto the plate, leading to uneven coating of the baking gum and the formation of fine spots after baking. Solution: Reduce washing pressure and avoid water droplets on the plate surface before applying the gum.
No baking gum or protective solution applied If the plate is baked without a layer of baking gum or protective coating, oxidation or dust contamination can occur under high temperature. Solution: Always apply a uniform layer of baking gum or protective solution before baking to protect the plate surface.
Incorrect baking temperature or duration Overheating or overbaking may damage the surface layer of the plate and cause contamination. Solution: Control the baking temperature and time carefully. Generally, 220°C for less than 5 minutes is recommended (adjust according to the plate type).
Uneven application of baking gum If the baking gum is applied unevenly, areas with thicker coating may heat differently and cause stains. Solution: After applying the gum, use a blade to gently smooth the surface for an even and consistent layer.
