Powder coating peeling can occur due to several reasons, primarily related to improper preparation or application. Here are the main causes and ways to improve adhesion:

Causes of Peeling

Inadequate Surface Preparation

The most common reason for powder coating to chip or peel is improper surface preparation. This includes:

• Insufficient cleaning or degreasing

• Failure to remove existing corrosion or sediment

• Lack of proper surface roughening

Incorrect Pre-Treatment

If the surface is not properly pre-treated, it can lead to poor adhesion. This involves:

• Cleaning the material

• Stripping away corrosion

• Degreasing (if applicable)

• Creating a surface that powder coating can adhere to

Improper Coating of Edges and Corners

Edges and corners are often challenging to coat properly, leading to chipping or cracking.

Incorrect Curing

Both under-curing and over-curing can cause adhesion issues. Under-cured coatings may chip easily, while over-cured coatings can show discoloration.

Incorrect Coating Thickness

Applying too little or too much powder can lead to adhesion problems. Too thin a layer may leave the surface unprotected, while too thick a layer can result in poor adhesion and cracking.

Environmental Factors

Extreme heat, cold, or exposure to harsh substances like dirt and salt can accelerate coating wear.

Improving Adhesion

Proper Surface Preparation

• Ensure thorough cleaning and degreasing of the surface.

• Use appropriate blasting or chemical pre-treatment methods.

Optimize Pre-Treatment Process

• For aluminum, consider using a dry-in-place nonchrome seal rinse or a chrome seal rinse.

• Ensure proper monitoring of all process parameters during pre-treatment.

Correct Curing

• Ensure the powder coating receives sufficient energy to achieve optimal properties.

• For two-layer systems, consider using a "green cure" method to enhance interlocking between primer and topcoat.

Proper Application Technique

• Pay special attention to edges and corners during application.

• Maintain correct powder thickness as per manufacturer specifications.

Quality Control

• Perform adhesion tests, such as the cross-cut test (ISO 2409) or boiling water adhesion test, to assess coating quality.

Hope this helps! 😊

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