Introduction: The Hidden Cost of Failed Corona Treatment
You’ve invested in corona treatment equipment. Your operators run the material through treatment before every print run. Quality control signs off. Everything looks good—until the printed rolls come back with adhesion failures, delamination, or customer rejections. Corona treatment failure rarely happens suddenly—it develops gradually as equipment, materials, and conditions drift out of control.
The brutal truth? Corona treatment failure is often invisible until it’s too late.
A leading flexible packaging converter discovered this the hard way: after three months of intermittent adhesion problems, they traced the issue back to inadequate corona treatment. The cost? $127,000 in rejected material, rewrites, and lost customer confidence. The worst part? Simple surface energy testing would have caught the problem within 24 hours.
This comprehensive guide reveals the five telltale signs that your corona treatment system isn’t performing—and more importantly, how to detect and fix these problems before they impact your bottom line.
What you’ll learn:
- The 5 critical warning signs of corona treatment failure
- Precise testing protocols to verify treatment effectiveness
- Root cause analysis for each failure mode
- Preventive maintenance strategies that actually work
- When to repair vs. replace treatment equipment
Understanding Corona Treatment Basics
Before we identify failure modes, let’s establish what successful corona treatment should achieve.
What Corona Treatment Does
Corona treatment is an electrical surface treatment that increases the surface energy of plastic films and other substrates through oxidation. When working correctly, corona treatment:
- Increases surface energy from typically 30-32 dynes/cm (untreated polyethylene) to 40-46 dynes/cm
- Creates polar functional groups on the material surface
- Enables ink, coating, and adhesive adhesion that would otherwise fail
- Provides consistent, predictable results across the full web width
Target Surface Energy Levels
| Application | Minimum Surface Energy | Ideal Range |
| Water-based flexo inks | 40 dynes/cm | 42-46 dynes/cm |
| Solvent-based inks | 38 dynes/cm | 40-44 dynes/cm |
| UV inks | 40 dynes/cm | 42-46 dynes/cm |
| Adhesive lamination | 42 dynes/cm | 44-48 dynes/cm |
| Coating applications | 44 dynes/cm | 46-50 dynes/cm |
When corona treatment fails to achieve these levels, adhesion problems inevitably follow.
Sign #1: Inconsistent Surface Energy Across Web Width
The Symptom
You test surface energy at the edges of the web and get 44 dynes/cm—excellent. But the center of the web measures only 36 dynes/cm. Print quality varies dramatically from edge to center, with ink adhesion failing in specific zones.
Why It Happens
Cause: Uneven electrode gap or worn electrodes
Corona treaters use electrodes that must maintain a precise, uniform gap across the entire web width. Over time:
- Electrodes wear unevenly due to arcing
- Mechanical stress causes electrode distortion
- Gap spacing drifts from specification
- Power distribution becomes uneven
Typical gap specifications:
- Standard gap: 1.5-2.0mm (0.060-0.080 inches)
- Tolerance: ±0.1mm (±0.004 inches) across full width
- Critical impact: Every 0.1mm gap increase reduces treatment by approximately 2-3 dynes/cm
How to Test
Equipment needed:
- Dyne test pens (range: 32-46 dynes/cm in 2-dyne increments)
- Ruler or measuring tape
- Lab notebook for recording data
Testing protocol:
| Position | Distance from Edge | Surface Energy (dynes/cm) | Pass/Fail |
| Edge L | 2″ | 44 | Pass |
| Quarter L | 25% width | 42 | Pass |
| Center | 50% width | 36 | FAIL |
| Quarter R | 75% width | 42 | Pass |
| Edge R | 98% width | 44 | Pass |
Failure criteria: Variation >4 dynes/cm across web width indicates problem.
Conclusion: Transform Problems Into Preventable Events
Corona treatment failure doesn’t have to be a mystery. The five signs we’ve covered—inconsistent cross-web treatment, rapid decay, visible arcing, material-specific problems, and over-treatment damage—all have clear causes and documented solutions.
The key insight: Problems that seem sudden actually develop over days or weeks. Systematic testing catches them early, when they’re easy and cheap to fix.
Remember: A $400 investment in proper testing equipment prevents $50,000+ annual losses from adhesion failures.
The question isn’t whether you can afford to implement systematic corona treatment testing. The question is: Can you afford not to?
Resources and Further Reading
The Complete Guide to Dyne Test Pens: Surface Energy Testing for Print & Packaging Excellence
Why Ink Won’t Stick to Plastic: The Surface Energy Problem
ISO 8296: Dyne Test Pens for Accurate Surface Testing
About Kolorguide
We provide precision surface energy testing solutions and technical expertise for the packaging, printing, and converting industries. Our dyne test pens, technical guides, and consulting services help manufacturers eliminate adhesion problems and achieve consistent, predictable results.
Contact us for specific technical questions about your corona treatment application or to discuss customized testing protocols for your facility.
