This article is part of the FLEXO FLAW FIXING series

In the world of flexo printing, achieving the perfect colour balance is paramount to producing high-quality prints. However, printers are sometimes faced with the challenge of colour strength that appears too high or intense in flexo printing.

This phenomenon can detract from the overall appearance of the print, causing problems ranging from aesthetic imbalance to physical damage to the printed material. Identifying the causes and implementing effective remedies are critical steps in addressing this issue.

Causes and Remedies

High Volume Transfer from Anilox Roller
  • Cause: Overly vivid colours are often caused by the anilox roller transferring too much ink. This excessive transfer results in a saturation that overshadows the intended colour balance.
  • Remedy: Switching to an anilox roller with a reduced cell volume can alleviate this problem and provide lighter ink transfer. Regular inspection and cleaning of the screen roller will also prevent ink buildup and maintain consistent ink transfer.
Ink Viscosity Too High
  • Cause: High viscosity in ink can prevent it from spreading evenly, causing some areas to show more intense colour than intended.
  • Remedy: Adjusting ink viscosity by adding solvents or mixing inks can result in more uniform distribution. Consistent monitoring of ink consistency prior to printing can prevent viscosity-related problems.
Too Strong Ink Recipe
  • Cause: Sometimes the initial ink formulation is too strong, resulting in too much pigment in the print.
  • Remedy: Diluting the ink mixture by adjusting the pigment concentration can produce a more balanced colour. Implementing a protocol for testing ink formulations on small samples prior to full production runs can help identify and adjust overly strong formulations in a timely manner.
Incorrect Doctor Blade Settings
  • Cause: Incorrectly adjusted doctor blade pressure and angle can result in inconsistent ink application, contributing to intense colour patches.
  • Remedy: Fine-tuning the doctor blade settings will result in a more uniform layer of ink. Routine checks for wear and proper doctor blade alignment can help maintain optimal ink application.
Material and Press Adjustment Discrepancies
  • Cause: Using inappropriate substrates or improper machine settings can exacerbate the colour saturation problem because not all materials react to ink in the same way.
  • Remedy: Selecting substrates known to work well with the chosen ink types and adjusting the printer settings to match the material properties can greatly improve colour balance. Pre-test runs with new materials can identify potential discrepancies prior to production.

Conclusion

The problem of high colour strength in flexo printing is multifaceted and influenced by a variety of operational and material factors. The key to overcoming this challenge is a thorough understanding of the potential causes and the implementation of strategic remedies.

By taking a proactive approach that focuses on equipment maintenance, material selection, and ink formulation, printers can maintain the delicate balance required to produce prints with perfect colour intensity. Ensuring the beauty and integrity of flexo prints requires not only attention to detail, but also an ongoing commitment to quality and precision.