The 7 Mistakes to Avoid When Applying Epoxy Resin

Epoxy resin is a material with exceptional performance, widely used for both artistic and technical projects such as river tables, laminating, casting, and composite applications. However, achieving a successful result requires precision and careful application.

Even minor mistakes can completely compromise the final result: bubbles, sticky surfaces, loss of transparency, or improper curing.

Here are the 7 most common mistakes you should absolutely avoid to achieve a professional finish.

1. Incorrect Resin / Hardener Ratio

This is the most common — and most critical — mistake.

Each epoxy system has a precise mixing ratio (for example: 100:35, 2:1, etc.). An incorrect proportion can lead to:

  • Incomplete curing
  • Sticky or soft surfaces
  • Loss of mechanical strength

Always follow the manufacturer’s recommended ratio, whether measured by weight or by volume depending on the system.

2. Poor or Insufficient Mixing

Even with the correct ratio, improper mixing can ruin your project.

A poorly homogenized mixture may cause:

  • Soft spots
  • Cloudy streaks
  • Uneven curing

Pro Tip:

  • Mix slowly for 2 to 3 minutes
  • Scrape the sides and bottom of the mixing container
  • Transfer the mixture into a second container and mix again

3. Working at the Wrong Temperature

Temperature plays a key role in the epoxy curing reaction.

  • Too cold (<15°C / 59°F) → thick resin, bubbles, poor curing
  • Too hot (>30°C / 86°F) → overly fast reaction, overheating

The ideal working temperature is between 18°C and 25°C (64°F to 77°F) in a stable environment.

4. Neglecting Surface Preparation

A poorly prepared surface is often the cause of visible defects.

Common issues include:

  • Poor adhesion
  • Bubble release from porous wood
  • Contamination from dust or grease

Best Practices:

  • Sand and thoroughly remove dust
  • Degrease the surface if necessary
  • Apply a sealing coat on porous materials such as wood

5. Pouring an Incorrect Thickness

Every epoxy resin has a maximum recommended pouring thickness.

Exceeding this limit can cause:

  • Overheating (exothermic reaction)
  • Cracks
  • Yellowing
  • Warping or deformation

Example:

  • ARTPOXY 20 type resins → thin pours
  • ARTPOXY 60 type resins → deep pours

Always choose the appropriate system for your project.

6. Poor Bubble Management

Bubbles are the number one enemy of transparent epoxy projects.

They can originate from:

  • The mixing process
  • The substrate (especially wood)
  • The surrounding environment

Solutions:

  • Gently heat the surface with a torch or heat gun
  • Pour slowly and carefully
  • Use a resin specifically designed for casting applications

7. Failing to Protect the Resin During Curing

Once poured, epoxy resin remains sensitive for several hours.

Potential risks include:

  • Embedded dust particles
  • Insects
  • Surface imperfections

Pro Tip:

  • Protect the project with a box or plastic cover
  • Work in a clean environment

Conclusion

The success of an epoxy resin project depends not only on the quality of the product, but also on the precision of the application process.

By avoiding these 7 mistakes, you greatly increase your chances of achieving:

  • Perfect transparency
  • Optimal curing
  • A professional-quality finish

Whether you are a beginner or an experienced user, these best practices are essential to fully benefit from the performance and versatility of epoxy systems.