Epoxy vs Resin — Which Reigns Supreme?

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Woodworking is a craft that marries creativity and technical skill. Among the many elements woodworkers use to enhance their projects, epoxy and resin are versatile materials that can add aesthetics and durability.  

However, the distinction between epoxy and resin is often blurred, leading to confusion and potential project mistakes. In this comprehensive guide, I delve into the nuances of epoxy and resin, unraveling their differences, characteristics, and applications within woodworking.

Exploring Resin: Nature and Hardening

Before going into the comparison between epoxy and resin, it’s essential to understand the fundamental nature of the resin. Resin is a natural or synthetic compound that is liquid but hardens under specific conditions. 

This transformation occurs through polymerization, where the resin molecules link together to form a solid structure.

This process can be initiated by mixing the resin with a hardener, resulting in a chemical reaction that solidifies the mixture. Alternatively, certain resins can be cured using ultraviolet (UV) light exposure.

preparing Upstart Epoxy Deep Pour Epoxy Resin Kit DIY

Differentiating Resin and Epoxy

Epoxy is a type of resin that falls within the broader category of resins. Epoxy resins are specifically designed as two-part compounds consisting of a resin component (Part A) and a hardener component (Part B). 

When these two parts are mixed in precise proportions, a chemical reaction occurs, transforming the liquid mixture into a hardened, durable material. 

This characteristic makes epoxy resin highly popular among woodworkers due to its straightforward measurement and mixing process.

It’s crucial to emphasize that epoxy is not an opposing material to resin; instead, it’s a subset of resins. Therefore, the notion of a “resin vs. epoxy” battle is a misnomer. Both epoxy and other types of resins have their unique qualities and applications.

Varieties of Resin Types: Polyurethane and Polyester Resins

UV resin craft

In addition to epoxy, two other common types of resin used in woodworking are polyurethane resin and polyester resin. Polyurethane resins are known for their relatively short working time – when the resin remains liquid after mixing – before they harden. 

This characteristic requires woodworkers to work when using polyurethane resin. 

On the other hand, polyester resins cure a rigid state, but their usage requires careful consideration of the hardener-to-resin ratio, especially concerning the thickness of the pour. Additionally, polyester resins are notorious for their strong odor during curing.

Determining Epoxy Resin Formula and Identification

I’ve been around the block with different resins, and let me tell you, knowing your epoxy is the cornerstone of any woodworking project you take on. This information is typically available on the resin kit label or in the product description. 

Manufacturers also provide safety data sheets for their products, which can be valuable. But let’s be real, sometimes you just need to ask someone who’s been down this road. I’ve learned that leaning on the expertise of suppliers or seasoned crafters can save a ton of time and headache to ensure you’re barking up the right tree with your project.

Choosing the Right Epoxy Resin for Your Woodworking Project

filling cracks with FGCI Deep Pour Epoxy Resin Kit Crystal Clear Liquid Glass

Selecting the best epoxy resin for thick pours and any woodworking project is akin to choosing the perfect paint for a masterpiece. Epoxy resin comes in various formulas, each tailored to specific applications and requirements.

The key to making an informed choice is to visualize the outcome you desire for your project. Are you aiming to coat a surface or fill a mold? This distinction will guide your choice between two main categories of epoxy resins: surface coating (doming) resins and casting resins.

Criteria

Surface Coating (Doming) Resins

Casting Resins

Viscosity

Thick and self-leveling

Very fluid

Maximum Pour Depth

Up to 1/8 inch

Up to several inches

Cure Time

Quick

Slower

Working Time

Short

Longer

Applicability

Even, glossy coats

Large projects

Ideal For

Countertops, tumblers, painting

River tables, molds

Limitation

Not suitable for deep pours

Requires dam/frame

Quantity Considerations and Proper Mixing Technique

When working with epoxy resin, the quantity you mix at once is crucial to achieving successful results. Mixing too much resin can lead to rapid heat generation, while too little may result in incomplete curing. Follow the mixing instructions provided with your epoxy resin kit meticulously.

Epoxy resin kits typically consist of a resin component and a hardener component. Precisely measuring these components in the specified ratios is essential for the chemical reaction to occur correctly.

Understanding Curing Times and Working Time

curing for 2nd coat

Curing times for epoxy resins vary depending on the specific formula you use. Some epoxy resins can cure within a few hours, while others may take a few days. I always stick to the script – which is the manufacturer’s instructions – to nail down those curing times.

On the other hand, working time refers to the duration during which the mixed epoxy resin remains in a liquid state and can be manipulated. Over the years, I’ve gotten pretty good at planning my moves during this window. Because once that resin starts to harden, the clock’s ticking on getting the whole woodworking project into place. 

Hardness and Mix Ratios: Balancing Strength and Precision

The hardness of cured epoxy resins can vary between different formulas. For instance, some casting epoxy resins offer flexibility in mix ratios, allowing for different hardness levels. Epoxy resin mix ratios are typically consistent, employing a 1:1 ratio of resin to hardener [1]

Accurate measurement of these ratios is critical, as deviations can lead to curing issues and compromised results.

UV Resistance and Susceptibility to Bubbles

Both epoxy and casting resins can contain UV inhibitors, but it’s important to note that exposure to UV light can cause yellowing over time, particularly in thick, standalone casting projects. (But how about UV resins? Find out more next.)

epoxy bubbles

Proper surface preparation, sealing, and appropriate protective finishes can mitigate these effects.

Both resins can also be susceptible to bubble formation during the curing process. Surface preparation and proper mixing techniques significantly minimize the presence of bubbles in your epoxy projects. But if you encounter issues, check this post to fix epoxy mistakes.  

Heat Tolerance and Resistance in Woodworking

Considering heat tolerance and resistance is crucial, especially when creating items that may come into contact with hot objects, such as coasters, tabletops, or kitchen accessories. 

Most epoxies I’ve used, including casting and coating varieties, get a little too cozy with heat, starting to soften around 120-150°F. However, high-heat epoxy systems designed for such applications can withstand higher temperatures.

Exceptions to the Rules: Flexibility in Application

Upstart Epoxy Deep Pour Epoxy Resin Kit DIY on wooden shelf

Now, for all the rules I’ve laid out in this guide, woodworking is an art form that loves its exceptions. I’ve seen woodworkers, myself included, bend the typical uses of epoxy and casting resins beyond their intended use. 

For instance, casting resins can serve in coating applications, but additional precautions and adjustments might be necessary. Similarly, coating epoxies can be employed for casting projects, but layering and other techniques might be required.

Conclusion

Epoxy and resin are two remarkable materials that open up a world of possibilities in woodworking. Woodworkers can confidently embark on projects incorporating these versatile materials by understanding their distinctions, characteristics, and applications. 

Whether seeking to create glossy surfaces, intricate molds, or durable finishes, epoxy, and resin offer various creative solutions. Armed with this knowledge, you can navigate the world of woodworking with precision and innovation.

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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