There's epoxy, and there's resin, and then there's epoxy resin. But what's the difference? At Carved, we use epoxy resin to create our wooden cellphone cases. Still, people always ask us to clarify the differences between these materials. If you, too, are curious about what sets resin apart from epoxy, we're here to explain.
You may be getting ready to explore the world of resin art, or you want to know what goes into creating these beautiful pieces. Let's compare resin and epoxy.
What Is the Difference Between Resin & Epoxy?
Since many commonly use "epoxy" to refer to the cured end product of epoxy resin (the use of which involves mixing resin with a hardener or exposing it to UV light), there can be confusion around the two terms.
Resin, which can be natural or synthetic, is standard in crafts, coatings, and low-stress applications since it's moderately solid and flexible. Meanwhile, epoxy, a synthetic resin, comprises an epoxy resin and a hardener. Its superior strength, durability, and chemical resistance make it ideal for applications where high-performance standards are crucial, such as in construction projects.
Resin is often less expensive and more flexible, while epoxy is generally more costly and more rigid. Epoxy typically offers better clarity and resistance to yellowing.
Different Composition Types
- Epoxy resin results from a chemical reaction between a resin and its corresponding hardener, often termed a "curer." It's a thermosetting material that permanently sets and hardens when exposed to heat. It has strong adhesive properties, durability, and resistance against heat and chemicals.
- Polyester resin, another common thermosetting material, is more brittle than epoxy resin. It's used in reinforcement applications, such as fiberglass repair kits. Polyester resin is also cost-effective and shared in the marine industry.
- Urethane resins range widely in terms of their hardness and flexibility, making them ideal for applications that demand high performance and high-impact strength. They are water-based, non-toxic, and easy to work with; they offer exceptional detail reproduction and have good resistance to high temperatures and chemicals.
Hardness Scale Comparisons
Hardness refers to a material's resistance to permanent indentation or deformation. Epoxy resin has a higher bond strength, degree of hardness, and better durability than its polyester resin counterparts. Its strength, coupled with its heat resistance, makes epoxy the preferred adhesive in high-stress environments.
Meanwhile, art resins are slightly more flexible to accommodate handling, and coating resins are generally more challenging and scratch resistant.
Viscosity & Application Methods
Viscosity (the thickness of the substance) varies significantly between epoxy and casting resins. Casting resin, with its high viscosity (thinness), is suitable for deep pours and filling intricate molds, allowing for bubble-free finishes. Still, it's more likely to slide around as you work.
In contrast, epoxy resin has a low viscosity (thick). It traps more bubbles (rise slowly through the thick substance), making it ideal for surface applications like countertops and art projects rather than deep pours.
Curing Process & Time
The curing process and time distinctly differ between epoxy and resin. Epoxy resin generally has a longer curing time than polyester and polyurethane resins, allowing for more working time. Epoxy resin's curing time largely depends on the chemical reaction between the epoxy and the hardener, which typically spans several hours.
Common Uses in Various Industries
Epoxy's higher bond strength and durable structure make it preferable as an adhesive, particularly within craft, construction, and industrial sectors. Epoxy can also serve as a protective coating, including but not limited to storage tank linings, bund wall linings, and resin floors. Meanwhile, polyester resin is more brittle without reinforcement. Still, it fulfills a niche in surface repairs across several industries.
Practical Applications: When to Use Resin vs Epoxy
How do people choose between resin and epoxy for their art projects, industrial uses, or carpentry tasks? The material's unique characteristics, uses, and benefits are the answer.
Coating Surfaces with Epoxy
Epoxy resin is your go-to solution for a high-strength, durable, and clear-finish coating. It's known for its sealing abilities and is ideal for arts and crafts and industrial use.
The thermosetting resin hardens upon curing, making it highly effective at protecting surfaces. Its resistance to chemicals makes epoxy a suitable finish for surfaces that will be exposed to harsh conditions. Whether using resin on a wooden table, a garage floor, or a boat deck, epoxy's durability can withstand high-traffic usage and harsh weather.
Utilizing Casting Resin for Molds
Casting resin is often more suitable for molding, jewelry, and figurines. Its lower viscosity (thinness) than epoxy, which is thicker, allows casting resin to flow into and faithfully replicate intricate details.
Despite its lower hardness than epoxy, casting resin is highly durable and provides a clear, glossy finish. Porosity isn't a significant concern for casting resin, making it an excellent choice when you want to encase objects without the fear of air bubbles distorting the result.
Working With Resin vs. Epoxy
Let's review some practical aspects of handling resin and epoxy, focusing on preparation, mixing techniques, managing your working time, and achieving a flawless finish.
Preparing & Mixing Techniques
Typically, epoxy resin consists of two parts: the resin and the hardener. They facilitate a chemical reaction that transforms the liquid mixture into a solid substance. The mixing ratio is often 1:1 (equal proportions of resin and hardener). Alternatively, the ratio might be 2:1 for coating resins, meaning twice the amount of resin to hardener.
Managing Your Working Time
With resin or epoxy, "working time" refers to the time you have after pouring and before the material matures and becomes unworkable. Due to its slower cure times and extended working time, casting resin is ideal for projects such as jewelry or molds that require intricate work and attention to detail.
In contrast, epoxy cures faster and has a shorter working time, making it appropriate for larger surfaces that need to be solidified quickly. Keep in mind that temperature can impact working hours. For instance, a hot environment might hasten the curing process.
Dealing With Air Bubbles
A challenge when using epoxy or casting resin is dealing with air bubbles, which can hinder a smooth, clear finish. Aim for thin, gradual pours instead of thick, sudden layers to mitigate trapped air bubbles during application. A pro tip is to use a heat gun or a torch over the surface immediately after pouring. This releases any trapped air for a flawlessly smooth and bubble-free finish.
Health & Safety Precautions
These materials can present a mild health hazard if you handle them correctly. Both epoxy and polyester resins require the appropriate protective gear, such as gloves and safety glasses. Having adequate ventilation is also essential to avoid prolonged exposure to the fumes, which can cause respiratory issues.
Frequently Asked Questions
What is the difference between casting resin and epoxy resin?
Casting resin and epoxy resin are versatile materials but differ in their applications. Casting resins are ideal for creating deep molds due to their low heat output during curing. In contrast, due to their high durability and heat resistance, epoxy resins shine in coating and laminating applications.
Is epoxy resin waterproof?
Epoxy resin is highly water-resistant, making it an excellent choice for pavement sealing and repairs, such as using epoxy resin on wood cracks. However, it isn't entirely waterproof, meaning it can't completely prevent water penetration under certain conditions.
Are there disadvantages to using resin?
While resin provides robust and durable surfaces, it may not be suitable for areas with heavy and frequent traffic. Continuous wear and tear could cause the surface to crack, leading to more severe damage.
Does epoxy resin the same as plastic?
Yes, epoxy resin is a type of plastic. Its plastic-like properties contribute to its strength, durability, and versatility in various applications.