This article is part of the FLEXO FLAW FIXING series

In the precision world of flexo printing, skip-out effect is like an unwelcome ghost haunting the presses with less-than-perfect prints. When areas of an image that should be covered with a smooth layer of ink appear patchy or incomplete, the phenomenon is known as skip-out. It’s a subtle but destructive flaw that can turn what should be a stunning piece of print into a rejected piece of waste.

Identifying Skip-Out Effect in Flexo Printing

Identifying skip-out is critical to maintaining flexo quality. It appears as missing dots or incomplete areas within a printed image where ink has failed to transfer or adhere properly. Unlike smudging, which adds unwanted ink marks, skip-out takes away, leaving a void where there should be ink or varnish. It occurs in vignettes, text and fine image detail, areas where precision is critical.

Causes and Remedies for Skip-Out

Every problem has a cause, and in flexo there are several factors that can lead to skip-out. Identifying these can help printers implement effective solutions.

Press Vibration and Stability
  • Cause: Excessive vibration from the press can cause minute disruptions in ink transfer, leading to skip-out.
  • Remedy: Ensuring the press is properly maintained and components are secure will reduce vibration and maintain stability, thus minimising skip-out.
Mechanical Misalignment
  • Cause: If printing components such as the plate and anilox roll are not aligned, or if the print settings are incorrect, this can cause uneven ink transfer.
  • Remedy: Routine inspection of mechanical alignments and pressure settings will ensure that the press is operating with the precision necessary to prevent skip-out.
Anilox Wear and Damage
  • Cause: Over time, anilox rolls can become worn or damaged, resulting in an uneven surface that does not transfer ink consistently.
  • Remedy: Regular anilox roll inspections and rebuilds can prevent the ink transfer inconsistencies that cause skip-out.
Plate and Backing Material Wear or Damage
  • Cause: The printing plate and backing materials can wear out or become damaged, resulting in poor ink transfer.
  • Remedy: Regularly replacing or refurbishing plates and backing foams can maintain ink transfer quality and prevent skip-out.
Improper Substrate Condition
  • Cause: Uneven or contaminated substrates can disrupt ink adhesion, resulting in areas of skip-out.
  • Remedy: Pretreating substrates to ensure they are clean and have uniform surface energy can improve ink adhesion and reduce the risk of skip-out.
Suboptimal Substrate Tension
  • Cause: Inconsistent tension in the web can cause the substrate to vibrate or wrinkle, resulting in skip-out.
  • Remedy: Precise web tension control throughout the printing process can stabilise substrate transport and reduce the incidence of skip-out.
Inadequate Ink Formulation
  • Cause: Using an ink formulation that isn’t compatible with the substrate can also result in poor transfer and adhesion.
  • Remedy: Customise ink formulations for specific substrate materials to ensure effective ink transfer and adhesion, thereby reducing skip-out.

By addressing these common and overlooked causes, printers can take a proactive stance against skip-out. Regular equipment maintenance, careful calibration, and a well-managed print environment are critical to combating skip-out. In addition, by tailoring ink and platemaking process parameters to specific jobs, printers can significantly reduce the incidence of this challenging defect.

There’s no single solution to preventing skip-out, but a combination of maintenance, vigilance, and the right technology. Printers who understand why skip-out occurs and how to fix it are well on their way to delivering flawless, skip-free prints every time.

Conclusion

The battle against skip-out in flexo is one of vigilance and precision. Recognising the causes is half the battle; implementing effective remedies is the victory. By rigorously monitoring every stage of the printing process, from platemaking to the run itself, and ensuring that environmental conditions are optimal, the incidence of skip-out can be drastically reduced. The result is cleaner, more reliable printing that satisfies customers and maintains the integrity of the flexo printing industry.