Labelling Solutions
Achieving premium print quality: Tackling high coat weight challenges with GMX Anilox
By Stuart Mitchell, technical director print, Sandon Global A
s demand grows for premium label embellishments such as tactile fi nishes, metallics and heavy varnishes, converters are under increasing pressure to deliver standout results without compromising consistency. However, applying high coat weights across varied substrates presents a unique set of challenges in UV fl exo printing. For narrow web printers striving for repeatable, high-quality output, success hinges on a critical component: the anilox.
THE CHALLENGE OF HEAVY COATINGS Modern UV fl exo converters now have access to an expanding range of adhesives, coatings and speciality inks. These materials enable eye-catching and textured eff ects, that add shelf appeal, but can be diffi cult to manage on press, particularly when higher coat weights are needed. On substrates like coated and uncoated paper or fi lm, improper application can lead to common defects such as pin-holing, surface reticulation, mottling, or uneven laydown.
THESE ISSUES ARE OFTEN ROOTED IN ONE AREA: THE CHOICE OF ANILOX ENGRAVING. Each engraving consists of millions of microscopic cells that control the volume of material transferred to the substrate. If the cell structure isn’t optimised for the application, particularly with larger particle sizes or high-viscosity varnishes, the results can be unpredictable, wasteful and ineffi cient.
WHY STANDARD ANILOX ENGRAVINGS FALL SHORT
When it comes to heavy coatings, using a conventional deep cell anilox can create more problems than it solves. Many high-viscosity or particle-rich coatings contain particles up to 30 microns or more, signifi cantly larger than the typical 8-micron pigment found in process inks. These particles may become trapped in deep, narrow cells, causing plugging, inconsistent ink transfer and increased cleaning requirements.
Furthermore, excessive depth introduces variability. A plugged cell doesn’t just impact coat weight, it can reduce colour strength, aff ect varnish laydown and result in costly downtime. Standard engravings may also struggle to provide accurate coat weight control, especially when paired with diffi cult substrates.
THE SANDON GLOBAL SOLUTION: GMX ANILOX
Sandon Global’s patented GMX Anilox engraving (EP3408097B1 / US10994565) was developed specifi cally for high coat weight and tactile applications. Its wide, shallow and uniform cell structure enables smooth transfer of coatings with larger particle sizes, reducing the risk of cell blockage and ensuring consistent laydown.
Crucially, correctly calculating cell size relative to particle size is essential for good collection and release. If the cell is too small to accommodate the coating particles, the pigment and carrying medium can separate during doctoring. This results in inconsistent transfer, poor optical density and greater variability in print quality.
By removing multiple cell walls, GMX Anilox creates a fl at, open cell design that enhances evacuation and supports effi cient coating application. This unique cell geometry also improves ink release, reduces doctor blade friction and off ers more predictable dry coat weights. Its refi ned micro-fi nish minimises vibration and blade wear, contributing to better press stability and longer component life.
PREDICTABLE PERFORMANCE WITH COCAL However, anilox design is only one part of the equation. Sandon Global supports its GMX Anilox customers with its proprietary COCAL (Coat Weight Calculator) tool, which accurately predicts dry coat weights based on engraving characteristics, coating particle size and substrate behaviour.
With COCAL, converters gain data-driven insights
to fi ne-tune their print process, reducing overuse of consumables, improving effi ciency, and maintaining consistency across jobs. Even small optimisations in coat weight can result in signifi cant annual savings, particularly in high-volume operations.
PARTNERING FOR PRECISION
Flexo converters working with premium substrates and embellishment eff ects face increasing demands for precision and repeatability. Anilox specifi cation, while often overlooked, is one of the most decisive factors in determining print quality and process stability.
There’s no one-size-fi ts-all solution for heavy coatings. Variables such as substrate type, coating viscosity and particle size all play a role in selecting the right anilox. Sandon Global’s GMX Anilox provides a robust, tested solution that helps label printers reduce waste, avoid costly defects and maintain high standards in the face of growing print complexity.
By partnering with anilox engineering experts and selecting the right tools such as GMX Anilox and COCAL, converters can approach high-coat-weight applications with greater confi dence - ensuring that their labels not only look exceptional but perform consistently on every run.
20
July/August 2025
www.convertermag.com
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