Fisheyes, splotches, weird textures, and small round defects are among the most frustrating issues encountered when working with epoxy resin. While similar to dimples, these defects are almost always a direct result of contamination—a localized surface tension failure where the liquid epoxy retreats and pulls away, leaving a crater-like defect that often exposes the substrate underneath.

Understanding and controlling contamination is the key to achieving a consistently smooth, professional finish.

Why Fisheyes and Splotches Appear

The phenomenon where epoxy pulls away from a contaminated spot is known as “crawling” or “cratering.” This happens because the surface energy of the contamination (e.g., oil) is much lower than the surface energy of the liquid epoxy, causing the resin to be repelled.

The primary culprits are:

1. Silicone and Oil Contamination

This is the most frequent and persistent cause of fisheyes.

• Release Agents and Waxes: Trace amounts of mold release wax, spray silicone lubricants, or furniture polish/wax transferred from hands, tools, or the air.
• Contaminated Air: Silicone can travel long distances via HVAC systems or air drafts. If a silicone-based caulk was used nearby, or if aerosol cooking sprays are used in the vicinity, particles can settle on the wet epoxy.
• Dirty Tools or Containers: Reused mixing cups or dirty stir sticks can carry residue from previous projects or unrelated chemicals.
• Oil and Grease: Fingerprints, hand lotions, skin oils, or machine lubricants on the substrate surface.

2. Moisture and Humidity

While less common for sharp fisheyes, moisture can cause widespread texture issues.

• Substrate Moisture: If the material you are coating (especially wood) has a high moisture content, the moisture can leach out during the epoxy’s exothermic cure process, disrupting the surface and causing a splotchy, uneven texture.
• High Ambient Humidity: High humidity in the air can react with certain epoxy components (especially amine-based hardeners), leading to a hazy, waxy surface film often called “amine blush.” While not a fisheye, this certainly qualifies as a “weird texture.”

3. Substrate Outgassing

This typically causes a pattern of small, round defects that look like permanent bubbles or craters.

• Porous Materials: Wood, concrete, and porous composites contain trapped air. As the epoxy cures (which generates heat, an exothermic reaction), this heat expands the air within the substrate. The air then pushes its way out through the liquid epoxy, creating a bubble that, once popped, may leave a crater that doesn’t fully collapse before the epoxy gels.
• Insufficient Sealing: If a porous material is not properly sealed with a thin, preliminary “seal coat,” outgassing is inevitable when the main flood coat is applied.

Genuine Solutions for Flawless Epoxy Surfaces

Eliminating fisheyes and texture issues requires a multi-pronged attack focusing on cleanliness, preparation, and technique.

1. Zero-Tolerance for Contamination

• The Wipe-Down Protocol: Before pouring, meticulously wipe the substrate. Use a clean cloth and a recommended solvent like acetone or denatured alcohol (IPA). Crucially, use only high-purity solvents and wait until they have fully evaporated before applying the epoxy.
• Cleanliness Barrier: Ensure all nearby items—gloves, tools, plastic sheeting—are clean. Wear non-powdered nitrile gloves to prevent transferring skin oils or lotion. If you must use a dust-reducing tack cloth, test it first to ensure it leaves no oily residue.
• Isolate the Workspace: The work area must be sealed off from potential contaminants. Avoid using silicone sealants, spray lubricants, or even air fresheners in the curing area. If you use a spray adhesive on the back of the piece, ensure it is fully cured and isolated.

2. Substrate and Moisture Management

• Seal Coat is Essential (for Porous Materials): For wood, concrete, or other porous materials, always apply a thin, quick-curing seal coat first. This light application penetrates the pores and traps the air before the main, thicker layer is poured. Wait for the seal coat to gel or cure enough to block air (check your product’s specifications) before the final flood coat.
• Check Wood Moisture Content: If working with wood, use a moisture meter. Wood should typically be below 10% moisture content to minimize outgassing and moisture-related texture problems.
• Control Humidity: Use a dehumidifier in the curing space if the ambient humidity is above 50-60%. This helps prevent amine blush and promotes a clear, hard cure.

3. Application and Repair Techniques

• Addressing Fisheyes During Application: If fisheyes appear immediately after the pour, you have a brief window to correct them.
  • The “Torch Sweep”: A quick pass with a butane torch or heat gun can sometimes temporarily reduce the surface tension of the fisheye and allow the epoxy to flow back into the crater.
  • Wait and Repour (The “Wet” Fix): If the contamination is minor and widespread, wait 5-10 minutes. Sometimes the epoxy flows into the voids as its viscosity drops slightly with initial heat. If the defects persist, you must deal with the contamination source, then scrape off the entire layer and repour on a clean surface.
• Post-Cure Repair: If the epoxy has cured with fisheyes or splotchy texture:
  1. Sand Down: Allow the epoxy to fully cure (24-72 hours). Sand the entire affected area with medium-grit sandpaper (e.g., 180-220 grit) to remove the contamination points and create a rough surface for the next coat to adhere to.
  2. Clean: Clean the sanded piece thoroughly with a solvent to remove all dust and residue.
  3. Apply a Final Skim Coat: Apply a new, perfectly mixed, thin flood coat. This will fill the sanded imperfections and cure smooth, assuming the contamination source has been eliminated.