When it comes to wood repairs and restoration, two common products stand out: epoxy resin wood fillers and polyester resin wood fillers ( often referred to as auto body putties ). While both serve similar functions in repairing cracks, holes, and surface damage in wood, epoxy resin offers significant advantages in terms of strength, durability, and versatility. Here’s why epoxy resin wood fillers are the superior choice over polyester wood fillers.

Polyester resin filler AKA: auto body putty

**Polyester wood fillers are easily identifiable by the use of a cream like hardener and strong odor**

1. Superior Bonding Strength

Epoxy resin creates an incredibly strong bond with wood, making it a more reliable choice for long-term repairs. Unlike polyester fillers, which often shrink and pull away from the wood over time, epoxy soaks into the fibers and forms a tight, lasting connection. This deep penetration enhances adhesion and ensures that repairs remain intact for years, even under heavy use or environmental stress.

Dura-Fix epoxy resin wood filler

The dual-cartridge dispensing system meters the correct ratio every time saving time and material.

2. Greater Durability and Flexibility

One of the biggest downsides of polyester wood fillers is their brittleness. They tend to crack or break under pressure, making them less effective for structural repairs. Epoxy resin wood fillers, on the other hand, remains slightly flexible, allowing it to withstand natural wood movement caused by temperature and humidity changes. This flexibility makes it ideal for both indoor and outdoor applications where wood expands and contracts.

3. Waterproof and Rot-Resistant

Unlike polyester fillers, which can absorb moisture and eventually break down, epoxy resin is completely waterproof. This makes it an excellent choice for repairing wood exposed to high humidity, rain, or even submersion in water. Boat builders, deck restorers, and outdoor furniture manufacturers often prefer epoxy resin for this reason. Additionally, because it seals and stabilizes damaged wood, epoxy can prevent rot from spreading, making it a valuable tool for preserving older or decayed wooden structures.

4. Longer Working Time for Precision Repairs

Polyester wood fillers set quickly—sometimes too quickly—making them difficult to shape and manipulate. Epoxy resin wood fillers provides a longer working time, allowing users to carefully sculpt, shape, or mold it into the desired form. This is particularly useful for intricate wood repairs where precision is required. Once cured, epoxy can be sanded, drilled, and painted just like wood, resulting in a seamless and professional finish.

Large repairs without multiple build-ups

Dura-Fix epoxy wood resin can fill even large repairs with no slump or sag.

5. No Shrinking or Cracking

A common problem with polyester wood fillers is that they tend to shrink as they cure, leading to gaps or an uneven surface that requires additional filling and sanding. Epoxy resin wood fillers, however, cures without shrinkage, ensuring that repairs maintain their original shape and strength. This means fewer touch-ups and a more efficient repair process.

Conclusion

While polyester wood fillers may be cheaper and faster to apply, they lack the durability, flexibility, and waterproofing properties that make epoxy resin a superior choice. Whether you’re repairing rotted wood, sealing outdoor furniture, or crafting a custom wood project, epoxy resin provides a longer-lasting, more reliable solution. Investing in epoxy means stronger repairs, better protection, and greater versatility—making it the best choice for serious woodworkers and DIYers alike.

Why Epoxy Resin Wood Fillers Outperform Polyester Wood Fillers