Paint Adhesion Failure: Understanding Causes and Solutions

Paint Adhesion Failure can quickly damage an otherwise successful finishing project. Cracking, peeling, and flaking coatings not only affect appearance but can also lead to costly repairs, production delays, and customer dissatisfaction.

At GreenLight Coatings®, we have helped many manufacturers identify and solve coating challenges by looking beyond the surface problem. One of the most effective solutions is Application Specific Advanced Coatings™ (ASAC™), a technology developed by Van Technologies, Inc. under the GreenLight Coatings® brand.

ASAC™ coatings are designed around specific customer requirements by combining the correct chemistry with proper application methods. Achieving a reliable finish requires the right balance between coating formulation, equipment settings, and process conditions.

This approach is known as “Chemechanics” — the combination of coating chemistry and finishing mechanics.

Understanding Paint Adhesion Failure in Real Applications

A customer approached GreenLight Coatings® after experiencing serious coating problems on pre-primed door casing profiles. The issue involved cracking and flaking in recessed and transition areas after installation in two housing developments.

The applied material was a waterborne-UV curable coating applied through a reciprocating flatline spray process.

Initially, the finishing team believed the coating itself was responsible because the issue disappeared after switching to another paint material.

However, further investigation showed that the problem was more complex.

A proper coating evaluation required analyzing not only the paint but also the entire finishing system, including application equipment, production conditions, and operator practices.

Diagnosing the Root Cause

To determine the real cause of the Paint Adhesion Failure, GreenLight Coatings® performed a complete technical investigation.

The team began by collecting retained liquid samples from the original production batch and testing them in the quality laboratory. The returned coating material from the finishing operation was also analyzed and compared against the original control batch.

Additional inspections were performed at the construction locations where the failures occurred. These inspections included:

• Surface adhesion testing
• Review of finishing line operations
• Operator interviews
• Sample collection from production materials
• Detailed laboratory analysis

The goal was to identify whether the problem came from coating chemistry or the application process.

Key Findings From the Investigation

The analysis confirmed that the adhesion issue was real, but it was only occurring in specific areas along the profile.

The coating was performing correctly in other sections, which suggested that the material itself was not the main cause.

Microscopic inspection revealed that certain failure areas had excessive coating thickness, approximately 73% higher than expected.

A primer layer was also discovered beneath some removed coating flakes.

However, laboratory testing showed that the coating material met all required specifications. Chemical comparisons between the problem coating, control samples, and other production batches showed no significant differences.

This proved that the failure was not caused by defective coating chemistry.

The Real Cause Behind the Failure

The investigation revealed that the issue was related to a mechanical problem in the finishing process.

The repeated pattern of failure locations provided the key clue. The damaged areas appeared at regular intervals of approximately 8 to 9 inches along the profile.

This spacing matched the conveyor speed and movement pattern of the spray equipment.

The actual cause was determined to be a faulty air cap and/or fluid tip in the reciprocating spray system. The equipment was applying excess coating in repeated strips.

This extra material created conditions where “mud cracking” occurred as the coating dried.

The stress placed on the underlying primer layer caused it to separate, leaving partial primer residue on removed flakes.

The Importance of Chemechanics

This case demonstrates why Paint Adhesion Failure cannot always be solved by simply changing materials.

The performance of coating chemistry depends heavily on the mechanics used to apply it.

A high-quality coating can only perform properly when equipment, process settings, and operator practices are working together.

GreenLight Coatings® believes successful finishing requires understanding the complete system — not just the coating itself.

By identifying equipment issues early, manufacturers can prevent defective products, reduce waste, and avoid expensive corrective actions.

Proper maintenance of spray equipment, attention to process details, and understanding Chemechanics can make the difference between a reliable finish and a costly failure.

GreenLight Coatings® continues helping manufacturers develop better coating processes through technical expertise, advanced chemistry, and practical problem-solving.