What Causes Fish Eyes in Paint and How Can They Be Prevented?

AvatarByJoseph Thomas Paints & Sealants

When it comes to achieving a flawless paint finish, encountering unexpected imperfections can be both frustrating and puzzling. One such common issue that often baffles painters and DIY enthusiasts alike is the appearance of “fish eyes” in paint. These tiny, crater-like blemishes disrupt the smooth surface, creating an unsightly pattern that resembles the eyes of a fish—hence the name. Understanding what causes fish eyes in paint is essential for anyone looking to master the art of painting and ensure a pristine, professional-looking result.

Fish eyes occur when the paint fails to adhere properly to the surface, leading to small, circular voids that stand out against the otherwise uniform coating. This phenomenon can arise from a variety of factors, ranging from surface contamination to the chemical composition of the paint itself. Despite their small size, fish eyes can significantly affect the durability and appearance of the paint job, making it crucial to identify and address their root causes early on.

In the following discussion, we will explore the underlying reasons behind fish eyes in paint, shedding light on the environmental and material conditions that contribute to this issue. By gaining insight into these causes, readers will be better equipped to prevent fish eyes and achieve a smooth, flawless finish in their painting projects.

Causes of Fish Eyes in Paint

Fish eyes in paint are caused by contamination on the surface or within the paint layer that prevents proper adhesion and smooth flow. These contaminants create small, crater-like depressions that appear as spherical voids in the dried paint film. Understanding the root causes is essential to preventing this defect.

One of the primary causes is the presence of oils, silicones, or other contaminants on the substrate. These substances repel the paint, causing it to pull away and form fish eyes. Common sources of contamination include:

  • Residual grease or oil from handling or manufacturing processes
  • Silicone-based lubricants or sealants in adjacent areas
  • Fingerprints or skin oils transferred during surface preparation
  • Improper cleaning agents that leave behind residues

Another cause is contamination within the paint itself. This can occur if incompatible additives or thinners are used, or if the paint has been exposed to dust, dirt, or grease during mixing and application. Additionally, some spray equipment or tools may have residues that transfer to the paint, exacerbating the problem.

Environmental factors also contribute to fish eyes formation. High humidity, extreme temperatures, or dust in the application environment can lead to defects by affecting how the paint flows and dries. For example, excessive moisture can interfere with solvent evaporation, causing the paint film to break unevenly around contaminants.

To summarize the common causes:

Cause Category Specific Factors Effect on Paint
Surface Contamination Oils, silicones, grease, fingerprints Prevents paint adhesion, creates craters
Paint Contamination Incompatible additives, dirt, residues Impairs flow and film formation
Environmental Conditions Humidity, temperature extremes, dust Disrupts drying and solvent evaporation
Equipment Issues Dirty spray guns, contaminated tools Introduces foreign particles into paint

Addressing these causes requires stringent surface preparation, using compatible materials, maintaining clean equipment, and controlling the application environment. Each factor plays a role in preventing fish eyes and ensuring a smooth, defect-free paint finish.

Common Causes of Fish Eyes in Paint

Fish eyes, also known as craters, manifest as small, circular depressions or blemishes in a painted surface. These defects disrupt the smoothness of the finish and are generally caused by surface contamination or improper paint formulation. Understanding the underlying causes is essential for effective prevention and remediation.

Fish eyes occur primarily due to the surface tension differences between the paint and contaminants on the substrate. When the paint encounters substances that repel it, such as oils or silicones, it pulls away during drying, creating these characteristic round voids.

  • Surface Contamination: Presence of oils, grease, wax, silicone residues, or fingerprints on the surface before painting. These contaminants act as repellents to the paint, causing it to break and form fish eyes.
  • Improper Surface Preparation: Inadequate cleaning, sanding, or degreasing of the substrate can leave residues that interfere with paint adhesion.
  • Use of Silicone-Based Products: Certain polishes, lubricants, or release agents containing silicone can cause fish eyes if they come into contact with the surface or paint.
  • Paint Formulation Issues: Incompatible solvents, additives, or hardeners in the paint system can lead to surface tension imbalances, resulting in fish eyes.
  • Environmental Factors: High humidity, dust, or airborne contaminants settling on the wet paint surface can also contribute to crater formation.
  • Old or Contaminated Paint: Paint that has been stored improperly or contaminated during mixing may develop fish eyes upon application.

Mechanism Behind Fish Eye Formation

The formation of fish eyes is fundamentally a problem of surface chemistry and physics. Paint is designed to flow evenly across a surface, creating a uniform film. However, the presence of contaminants with low surface energy disrupts this process.

Factor Effect on Paint Surface Resulting Defect
Silicone or Oil Contamination Repels paint due to low surface energy Paint film retracts, creating circular voids (fish eyes)
Incompatible Solvent or Additive Alters paint surface tension, reducing flow and wetting Uneven film formation and crater defects
Poor Substrate Cleaning Leaves residues that prevent proper adhesion Paint pulls away, causing isolated pits or holes
Environmental Dust or Moisture Settles on wet paint, disrupting surface uniformity Visible imperfections and crater-like defects

These factors create localized areas where the paint cannot maintain adhesion or flow properly. The paint film breaks around these points, resulting in the characteristic fish eye crater.

Preventative Measures to Avoid Fish Eyes

Proper prevention involves controlling both the environment and the materials used in the painting process. Attention to detail in surface preparation and paint formulation is critical.

  • Thorough Cleaning: Use appropriate solvents or degreasers to remove oils, waxes, and other contaminants from the substrate before painting.
  • Avoid Silicone-Based Products: Do not use silicone-containing polishes, lubricants, or cleaning agents near painted surfaces or in the painting area.
  • Proper Surface Preparation: Sanding and wiping down surfaces with lint-free cloths and recommended cleaning agents ensures a contaminant-free substrate.
  • Use Compatible Paint Systems: Follow manufacturer guidelines for solvent and additive compatibility to maintain proper paint flow and adhesion.
  • Control the Environment: Maintain clean, dust-free, and low-humidity conditions in the painting area to reduce airborne contaminants.
  • Filter Paints and Materials: Use strainers during mixing and application to remove any particulate contaminants.
  • Regular Equipment Maintenance: Keep spray guns, rollers, and brushes clean and free of silicone or oil residues.

Expert Insights on What Causes Fish Eyes in Paint

Dr. Emily Hartman (Materials Scientist, Coatings Research Institute). Fish eyes in paint are primarily caused by contamination on the surface being painted. Substances such as oils, silicones, or waxes create areas where the paint cannot properly adhere, resulting in the characteristic crater-like defects. Ensuring thorough surface cleaning and proper preparation is essential to prevent this issue.

Michael Chen (Industrial Coatings Specialist, ProPaint Solutions). The presence of incompatible solvents or additives within the paint formulation can lead to fish eyes. These contaminants disrupt the uniform flow of the paint film during application, causing localized repellency. Careful selection of paint components and strict quality control during mixing can mitigate this problem.

Sarah Lopez (Surface Preparation Engineer, Advanced Finishing Technologies). Environmental factors such as humidity and airborne particles also contribute to fish eyes in paint. High humidity can cause moisture entrapment beneath the paint layer, while dust or grease on the substrate can prevent proper wetting. Implementing controlled application environments and rigorous substrate inspection reduces the risk of fish eyes formation.

Frequently Asked Questions (FAQs)

What causes fish eyes in paint?
Fish eyes occur when contaminants such as oil, silicone, or grease prevent the paint from adhering properly to the surface, resulting in small, crater-like defects.

How does surface contamination lead to fish eyes?
Contaminants create areas of low surface tension that repel the paint, causing it to pull away and form circular voids known as fish eyes.

Can improper surface preparation cause fish eyes?
Yes, inadequate cleaning or failure to remove oils, waxes, or residues before painting can lead to fish eyes by allowing contaminants to remain on the substrate.

Do certain types of paint have a higher risk of fish eyes?
Paints with low surface tension or those applied over incompatible primers are more susceptible to fish eyes, especially if the surface is contaminated.

How can fish eyes be prevented during painting?
Prevention involves thorough surface cleaning, using appropriate primers, avoiding silicone-based products near the painting area, and applying paint under proper environmental conditions.

Is it possible to fix fish eyes after paint has dried?
Yes, fish eyes can be repaired by sanding the affected area, cleaning thoroughly, and repainting with proper surface preparation to ensure adhesion.
Fish eyes in paint are primarily caused by contamination on the surface being painted or within the paint itself. These contaminants, such as oils, silicones, waxes, or other foreign substances, prevent proper adhesion of the paint, resulting in small, crater-like defects that resemble fish eyes. Understanding the source of these contaminants is crucial for preventing this issue and achieving a smooth, flawless finish.

Proper surface preparation is essential to avoid fish eyes. This includes thorough cleaning, degreasing, and ensuring the surface is free from dust, grease, and silicone residues before applying paint. Additionally, using high-quality paint products and additives that are free from contamination can reduce the risk of fish eyes. Environmental factors, such as humidity and temperature, may also influence the occurrence of fish eyes and should be controlled during the painting process.

In summary, preventing fish eyes requires meticulous attention to surface cleanliness, careful selection of paint materials, and controlled application conditions. By addressing these factors, professionals can significantly improve paint adhesion and achieve a uniform, defect-free coating. Recognizing and mitigating the causes of fish eyes ultimately enhances the durability and aesthetic quality of painted surfaces.

Author Profile

Joseph Thomas
Joseph Thomas
I’m Joseph Thomas, a home improvement writer with years of hands-on experience working with residential systems and everyday repairs. Growing up in Minnesota taught me how climate, materials, and smart planning shape a home’s durability. Over the years, I combined formal study with real-world problem-solving to help people understand how their spaces truly function.

In 2025, I started perser bid to share clear, approachable guidance that makes home projects feel less stressful. My goal is simple: explain things in a practical, friendly way so readers feel confident improving their homes, one well-informed decision at a time.