In flexographic printing, a clean anilox roller is essential for consistent print quality, stable colour, and predictable press performance. But one common misunderstanding still causes problems in many print shops:
You can’t truly tell if an anilox is clean just by looking at it.
The short answer? You can sometimes see that an anilox is dirty - but you can’t reliably confirm that it’s clean with the naked eye.
Let’s break down why.
There are surface-level signs of contamination that are easy to spot. If you’re seeing obvious buildup, the anilox is already past the point of needing attention.
You may notice dried ink or coating, a shiny or glazed appearance, streaks or banding, visible colour staining, or adhesive and varnish residue. These symptoms indicate that the roller is not clean and likely affecting print performance.
The real issue often hides inside the anilox cells. Without magnification, it’s impossible to inspect the microscopic structures where ink or coating residue tends to accumulate. This challenge has become even more critical with modern aniloxes featuring increasingly fine cell structures (1000+ LPI), making visual inspection far less reliable than with older, coarser rollers.
A roller may appear clean on the surface while still having 10–50% of its cells plugged. Even 20% cell plugging can result in noticeable colour shifts and print quality issues. Dried ink can settle at the bottom of the cells or bridge the walls, all of which contribute to volume loss - and that’s completely invisible to the eye.
As a result, an anilox might look fine but still cause problems on press: weak or inconsistent colour, dirty print, poor solids, or fading highlights. These issues may not be immediately linked to cleanliness, but often, the root cause is hidden cell contamination.
Visual checks can help catch major problems, but they should never be relied on as confirmation that the roller is clean.
The most effective way to verify cleanliness is with magnification. A handheld microscope or cell volume scanner allows you to inspect inside the cells, identify partial plugging, and track performance over time.
But even without a microscope, there are better options than just looking:
Apply water or cleaning foam to the surface of the anilox. If it beads up or pulls away unevenly, there’s likely still residue in the cells.
You should also watch for early warning signs like faded colours, dirty highlights, or uneven ink coverage. These can point to issues with cell volume or cleanliness, even if the roller looks clean.
Capatch.com offers a disposable liquid volume testing tool for anilox rolls, full coating gravure rolls, and tri-helical rolls. It is a single-use, contact-based tool that is applied directly to the roll surface.
Professional anilox cleaning machines use controlled pressure, specialised cleaning liquids, and precise timing to ensure complete cell evacuation, something manual cleaning often cannot achieve. These automated systems deliver consistent, deep cleaning that removes contamination from even the finest cell structures, reducing the need for cleanliness verification after every cleaning cycle.
Not all ink types leave the same residue. Water-based inks can dry in the cells, UV inks may form a glaze, and solvent-based inks can leave stubborn films. Each system needs its own inspection habits and cleaning frequency.
Aniloxes should be thoroughly cleaned after every job change, with deep cleaning performed using automated cleaning systems, so you can be sure the result is consistent and repeatable every time.
High-volume operations or challenging ink systems may require more frequent professional cleaning to maintain optimal performance.
Inadequate anilox cleaning has real business consequences. It leads to increased waste, longer setup times, more frequent colour adjustments, and potential premature anilox replacement costs. In a fast-paced Flexo environment, relying on eyesight alone just isn’t enough.
A roller that looks clean can still cause performance problems and increase downtime, waste, or customer complaints. A consistent, well-verified cleaning routine helps ensure reliable colour, faster changeovers, and fewer press disruptions.
Important Safety Note: Always follow proper handling procedures and safety guidelines when using cleaning liquids and equipment. Ensure adequate ventilation and use appropriate personal protective equipment.
Don’t let hidden contamination compromise your print quality. If you’re experiencing unexplained colour variations or print issues, consider having your anilox cleaning process evaluated by cleaning technology specialists who can recommend the most effective solutions for your specific operation.