What Causes Fish Eyes in Paint: Identifying and Preventing Auto Paint Imperfections

Fish eyes in paint are a common issue that many of us in the painting industry encounter. These small, crater-like imperfections occur during or immediately after the application of paint and can be quite frustrating to deal with.

The underlying cause of fish eyes is contaminants on the surface that repel the wet paint, preventing it from adhering and causing the paint to pull away, leaving behind small circular voids.

A paint can with fish eyes forming on the surface due to contamination or improper mixing

Common contaminants that lead to fish eyes include:
  • Oils and grease
  • Silicone
  • Wax
  • Water
  • Dust

These materials often originate from waxes, polishes, or even the environment itself.

Whether you’re an automotive professional or a DIY enthusiast, understanding what causes fish eyes and how to prevent them is critical for achieving a flawless finish.

To combat this, we ensure that surfaces are scrupulously cleaned and prepped before painting, as even tiny amounts of contaminants can cause significant defects in the paint film.

Identifying Paint Defects

When we talk about paint defects, two terms come up frequently: fisheyes and craters. Both are imperfections in the paint film that can significantly detract from a finish’s appearance and durability. Understanding their causes and characteristics is essential for diagnosing and preventing these issues.

Analyzing Common Issues: Fisheyes and Craters

Fisheyes are small, circular depressions that interrupt the smooth surface of a paint film. They occur when a contaminant, often silicone or oil, repels the wet paint. This contamination can originate from a variety of sources, including dirty air lines, improper surface cleaning, or even transfer from a worker’s skin.

Look for:

  • Small circular indentations in the paint surface.
  • Areas where the paint has receded, potentially exposing the undercoat or substrate.

Craters, much like fisheyes, are defects that present as depressions in the paint. However, they tend to be larger in size and may not be circular. Caused by similar contaminants that create fisheyes, craters can also result from particulate matter landing in the wet paint film.

Differentiating Fish Eyes, Craters, and Orange Peel

Understanding the distinction between fisheyes, craters, and orange peel is fundamental for any paint correction strategy. While fisheyes and craters are types of depressions in the paint film, orange peel is a texture issue characterized by a surface that resembles the skin of an orange.

Fisheyes:

  • Typically a few millimeters in diameter.
  • Result from contamination from oily substances.

Craters:

  • Larger than fisheyes.
  • Can be caused by contamination or particulate matter.
Defect Fisheyes Craters
Appearance Small, circular depressions. Larger, irregular depressions.
Cause Contamination from substances like oil or silicone. Contamination or foreign particles in paint.
Surface Texture Recession in paint film. More pronounced indentation than fisheyes.

Orange Peel:

  • An uneven texture that does not reflect light uniformly.
  • Caused by improper paint viscosity, poor application technique, or inadequate drying time.

Preparation and Prevention Strategies

To ensure a smooth and defect-free finish, we must pay careful attention to preparation and prevention strategies. This approach helps us to avoid paint flaws such as fisheyes.

Surface Preparation and Undercoating Techniques

Emphasis on Substrate Cleanliness:

Before we apply any undercoats or primer, it is crucial to start with a substrate that is free from contaminants.

Our first step involves sanding the surface to create a smooth base. Sanding not only removes imperfections but also promotes better adhesion of the undercoat.

Thorough Cleaning:

We must thoroughly clean the surface after sanding, ensuring that all dust, grease, and oil residues are removed.

This can be accomplished using a solvent cleaner designed for this purpose, rather than generic thinners. Here is a simple list to follow:

  1. Sand the surface to eliminate existing imperfections.
  2. Use specific solvent cleaners to thoroughly clean the surface.
  3. Apply an appropriate undercoat or epoxy primer to properly seal the substrate.

Preventing Paint Defects in the Work Environment

A Clean Workspace:

To prevent paint defects, we must maintain a clean and controlled work environment.

The presence of airborne contaminants like dust, oil, or silicone can easily result in fisheyes. Therefore, we regularly clean and filter the air in our painting area.

Equipment Maintenance:

Clean painting equipment is just as important as a clean environment.

We always ensure that our painting tools and airless guns are free of residues from previous jobs that could introduce contaminants into our new paint job.

This includes checking for residual fisheye eliminator additives that could cause problems when overused.

The Application Process for a Flawless Finish

Achieving a flawless finish in painting requires precise application of both basecoat and topcoat. This section shares our tips for ensuring a smooth application that helps to prevent paint defects like fisheyes.

Step-by-Step Guide to Applying Basecoat and Topcoat

Preparing the Surface

Before we begin, we ensure the surface is clean, dry, and free from contaminants.

Any grease, wax, or silicone residue can cause fisheyes, so we use a degreaser and follow it with a tack cloth to pick up any remaining dirt.

Applying the Basecoat

  1. After thorough preparation, we apply the basecoat. It’s crucial to mix the paint correctly and to check for the paint’s recommended application conditions.
  2. We use a spray gun for even application, holding it about 6-8 inches from the surface and moving in a consistent, controlled manner.
Layering the Topcoat

Once the basecoat is dry, we apply the topcoat.

It’s important to ensure the basecoat is completely dry to avoid reactions between the layers.

  1. We apply the topcoat with smooth, even strokes to prevent runs and sags.
  2. Multiple light layers are often better than one thick layer, as this helps to avoid defects and ensure a smooth finish.

Techniques for Achieving a Smooth Paint Finish

Consistent Spray Technique

Maintaining a consistent distance and motion while spray painting is key. We overlap each pass by about 50% to ensure complete coverage without heavy buildup.

Avoiding Over-application

Applying too much paint can cause runs and an uneven finish.

We carefully regulate pressure and paint flow, keeping our movements steady.

Advanced Solutions and Fixes

In addressing fisheyes in paint, it’s vital to utilize dedicated products and professional techniques for the most effective repair and prevention. Let’s explore specific strategies that will help rectify this problem.

Using Fish Eye Eliminator and Other Specialized Products

When fisheyes occur, applying a fisheye eliminator to the affected area can be a highly effective solution. This compound is specifically formulated to lower the surface tension, allowing the paint to level properly.

It is crucial to follow the manufacturer’s guidelines when adding the fisheye eliminator, as using too much or too little can affect the outcome.

For environments plagued by silicone or oil-based contaminants, moisture in the air supply may contribute to fisheyes. Here, investing in an advanced air filtration system designed to remove such impurities can prevent fisheyes from reoccurring.

Troubleshooting with Professional Techniques

Using solvents to meticulously clean the painting equipment and the surface before painting can significantly reduce instances of fish eyes.

It’s also beneficial to acquire training or watch instructional videos on the correct application of paints and use of equipment to ensure best practices are adhered to.

Cleaning a contaminated airless gun thoroughly or opting for silicone-free products can also be a part of the professional approach to avoid fisheyes in the paint job.
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