What causes color ghosting in flexo printing and how to avoid it? | Keshenglong&Shinko Guide

What Causes Color Ghosting in Flexo Printing and How to Avoid It?

Professionals in the flexo printing industry often encounter the challenge of color ghosting, where faint or unwanted images appear on prints. This article explores the core causes of flexo printing color ghosting and provides practical tips for preventing it, ensuring better print quality and system efficiency.

Common Causes of Color Ghosting in Flexo Printing

Ink Transfer and Substrate Issues

- Ink Over-penetration: Excess ink passes through the substrate, creating unwanted images.

- Substrate Absorbency: Inconsistent substrate materials can cause uneven ink absorption (Source: FTA, Flexography: Principles & Practices).

- Surface Treatment: Inadequate substrate surface treatment results in poor ink adhesion.

Mechanical & Press Settings

- Impression Pressure Misalignment: Uneven nip pressure can force ink into non-image areas.

- Plate Bounce: Excessive press speed or plate mounting errors lead to vibration and ghosting.

- Worn or Defective Plates: Damaged flexo plates promote subpar ink transfer.

Ink Formulation and Drying

- Slow Drying Inks: Prolonged wet ink transfer increases the chance of image repetition.

- Improper Ink Viscosity: Incorrect ink viscosity disrupts even transfer (Source: Sun Chemical White Papers).

- Solvent or Water Imbalance: Incorrect solvent/water mixtures prevent proper ink setting.

Printing Plate & Anilox Roller Issues

- Inadequate Plate Cleaning: Residual inks or dust on plates produce ghost images.

- Damaged Anilox Rollers: Non-uniform cell volume affects ink delivery and distribution.

Preventing Color Ghosting in Flexo Printing

Optimize Ink & Substrates

- Select inks tested for fast drying and proper transfer on chosen substrates.

- Ensure substrates receive recommended surface treatments, like corona or plasma.

Maintain Equipment

- Regularly inspect and replace worn flexo plates and anilox rollers.

- Calibrate press impression settings for balanced pressure across the web.

Fine-Tune Press Settings

- Adjust press speeds to avoid excessive plate bounce/vibration.

- Monitor ink viscosity with reliable viscometers for every print run.

Implement Consistent Cleaning and Maintenance

- Schedule routine plate and roller cleaning before each shift or job change.

- Use ultrasonic cleaning equipment for thorough debris removal.

Data-Driven QC & Process Control

- Utilize spectrophotometry for real-time color consistency monitoring (Source: FTA Resources).

- Review print samples at regular intervals to catch early signs of ghosting.

Additional Recommendations

- Adopt process audits using standardized test forms from industry organizations.

- Train operators on the effects of substrate and ink parameters.

- Partner with suppliers who offer technical support and process optimization guidance.

References:

- Flexographic Technical Association (FTA), *Flexography: Principles & Practices*

- Sun Chemical, *Ink Formulation White Papers*

- TLMI Technical Resources

Optimize your flexo printing performance by understanding and preventing color ghosting. For solutions tailored to your operation, connect with Keshenglong&Shinko’s flexo experts.