Introduction

Corona treatment should produce a stable, uniform electrical discharge across the full width of the web. When that discharge becomes unstable—visible sparks, crackling sounds, or excessive ozone odor—the process is no longer controlled.

This condition is known as arcing, and it is one of the most damaging and misunderstood corona treatment failures. Arcing does not simply reduce surface energy—it creates unpredictable treatment, accelerates equipment wear, and often leads to sudden adhesion failures.

This article explains what corona treater arcing really means, why it happens, how to identify it correctly, and how to eliminate it before it causes rejects or equipment damage.

This article is part of our complete guide:
5 Signs Your Corona Treatment Isn’t Working (And How to Test It)

What Corona Treatment Should Look Like

Under normal operation, corona discharge appears as:

• A uniform blue-violet glow
• Evenly distributed along the electrode length
• Accompanied by a steady, high-frequency hum
• With a mild, clean ozone scent

This indicates controlled ionization and consistent surface oxidation.

Arcing is the opposite.

What Arcing Looks Like in Practice

Common symptoms include:

• Bright white or blue “lightning” sparks
• Crackling, popping, or snapping sounds
• Strong, sharp ozone smell
• Dark zones where no corona is visible
• Fluctuating power readings on the control panel

When arcing occurs, some areas of the web are over-treated, others under-treated, and some not treated at all.

Why Corona Treater Arcing Happens

1. Carbon Buildup on Electrodes

Over time, corona electrodes accumulate carbonized residue from:

• Polymer vapors
• Additives
• Environmental contaminants

Carbon buildup creates high-resistance spots, forcing the discharge to jump as arcs instead of spreading evenly.

2. Worn or Damaged Electrodes

Electrodes exposed to repeated thermal and electrical stress may develop:

• Pitting from arc erosion
• Cracks or warping
• Uneven surfaces

These defects distort the electric field and promote arcing.

3. Insulator or Ceramic Failure

Ceramic or insulating components can fail due to:

• Micro-cracks
• Carbon tracking
• Moisture absorption

Once insulation degrades, electrical discharge escapes uncontrollably.

4. Environmental Conditions

High humidity and airborne particles increase arcing risk:

• Relative humidity above 70% lowers air breakdown voltage
• Dust particles act as arc initiation points
• Moisture films form on electrodes and substrates

5. Material-Related Issues

Certain material conditions promote arcing:

• Thickness variations that change the effective gap
• Conductive contaminants on the film surface
• Excessive moisture content

How to Identify Arcing Correctly

Visual Inspection (Most Effective)

1. Operate the treater in a darkened area.
2. Observe the discharge pattern:
   • Uniform blue-violet glow → Normal
   • Bright white sparks → Arcing
   • Dark zones → No treatment

Audio Cues

• Steady hum → Normal
• Crackling or popping → Arcing

Ozone Odor

• Light ozone smell → Normal
• Sharp, acrid smell → Excessive arcing

Electrical Indicators of Arcing

Monitor power behavior:

• Normal: ±5% power fluctuation
• Problem: >10% fluctuation or declining output at constant settings

Unstable power is a strong indicator of uncontrolled discharge.

Confirming Arcing with Surface Energy Mapping

Test surface energy in short machine-direction intervals (e.g., every 4 inches).
Arcing often creates a striped or patchy dyne pattern that correlates with visible discharge irregularities.

How to Stop Corona Treater Arcing

Immediate Actions

1. Reduce power temporarily
   • Prevent further electrode damage
2. Clean electrodes
   • Use manufacturer-approved solvents
3. Inspect insulators
   • Look for cracks or carbon tracking
4. Verify grounding
   • Poor grounding promotes unstable discharge

Preventive Maintenance Schedule

Replacement Criteria (Do Not Delay)

Replace components when you observe:

• Pitting deeper than 0.5 mm
• Carbon buildup that cannot be removed
• Cracked or tracking ceramics
• Electrode distortion greater than 0.2 mm

The Cost of Ignoring Arcing

• Electrode replacement: $800–2,500
• One rejected production run: $15,000–50,000
• Lost customer confidence: immeasurable

Arcing accelerates wear and often turns a minor maintenance issue into a major failure.

Why Arcing Is Often Misdiagnosed

Arcing is frequently blamed on:

• Material quality
• Ink formulation
• Operator error

In reality, arcing is almost always an equipment condition, not a material problem.

Prevention Checklist

• ☐ Inspect corona discharge daily
• ☐ Clean electrodes before carbon becomes visible
• ☐ Control humidity in the treatment area
• ☐ Track power stability over time
• ☐ Replace electrodes proactively

Key Takeaway

Corona treater arcing is a warning signal, not a cosmetic issue. It indicates loss of control in the treatment process and leads directly to inconsistent surface energy, adhesion failures, and accelerated equipment wear.

Early detection and routine maintenance transform arcing from a production crisis into a manageable maintenance task.

Related Reading

• 5 Signs Your Corona Treatment Isn’t Working (And How to Test It)
• Uneven Corona Treatment Across Web Width: Causes, Testing & Fixes
• Why Corona Treatment Decays Over Time (And How to Measure It Correctly)