Epoxy adhesives are long-lasting, versatile, and heat resistant. You can use them in almost any situation where two materials need to be glued together—for example, gluing a detail to a larger structure, binding subfloors, reinforcing a fastener, or model building (especially when you’re out of model glue). You can also use epoxy with various materials, including plastic, wood, masonry, and metal.
Continue reading to discover what epoxies are and why they are important in model building so you can choose the right glue.
What Is Epoxy Resin?
Epoxies are thermoset plastics created through two or more industrial chemical compounds’ reactions. Because of their toughness, chemical resistance, strong adhesion, and other specialized properties, epoxy resins are employed in various industrial and consumer applications. Wool, Styrofoam, rubber, and epoxy are just a few examples of polymers you may be familiar with.
Epoxy resins are made up of epoxides, highly reactive groups of molecules that harden (or cure) through chemical reactions caused by heating it to a high temperature or combining it with other substances. As polymer strands fashion into a hardened structure, this is the process through which the epoxy becomes “cross-linked.”
Two Types of Epoxy Adhesives
Epoxy adhesives are classified into two-part epoxies and one-part (or heat-cured). One-part epoxies cure faster but are not always as powerful as two-part epoxies.
Heat-Cured Epoxies
Heat-cured epoxies have numerous industrial applications, but they are rarely used in model building because of the high heat required for curing—even those that react at the lowest heat level must be exposed to temperatures of at least 200 ℉.
Due to its exceptional toughness, epoxy resin is used in a wide range of products, from medical devices and electronic components to missile warning systems and infrared telescopes.
Two-Part Epoxies
The two components needed for the chemical reaction are loaded separately in two-part epoxies. When the resin (also known as “steel”) is blended with the hardener, the result will change from a thick solution to putty to a fully cured and hardened material for up to 24 hours. To remove epoxy after it has hardened, use a scraper and soften it with paint thinner or alcohol if necessary.
Like their heat-cured counterparts, two-part epoxies have many industrial applications in aeronautical, automotive, and other manufacturing areas, and they’re especially common in boat building. They are also utilized in construction projects, where they are used to stick model building materials, attach countertops to substrates, fasten concrete elements to others made of stone, concrete, or metal, and secure decorative moldings in place.
Epoxy Resin’s Common Applications in Model Building
As Adhesives
Among the most common applications for epoxy resin is as an adhesive. Because of the epoxy’s strong properties, engineering and structural adhesives can be used.
Epoxy resin is commonly used to construct air crafts, vehicles, snowboards, and bicycles. However, epoxy adhesives are not only used in structural applications. You can utilize them in almost any application, including model building.
Epoxy is commonly used due to its numerous setting options. It can become rigid or flexible with transparent and opaque options available.
For Sealant and Coatings
Epoxy is also known for its corrosion-resistance properties, which makes it an ideal solution for many household objects that rust over time. Items such as metal containers, paint cans, and acidic foods are typically coated before use. This makes epoxy resin perfect for building metal models.
Another application for epoxy resin is decorative flooring. An epoxy resin is applied to terrazzo, chip, and other aggregate flooring options. Because it reduces the need for water consumption and pesticides, epoxy flooring is a more environmentally friendly alternative to traditional flooring options.
For Maintenance
Many consumers utilize epoxy resin to maintain and repair household objects due to its strong adhesive properties. Fragile items such as ceramic, glass, and china can be quickly repaired with epoxy resin, which helps secure snapped or broken items to the original piece.
Similarly, epoxy resin can be used on various model building materials. You can also repair models made of metal, wood, or similar synthetic materials. Applying epoxy resin to an otherwise fragile piece will create a tightly formed, thin barrier that attaches securely and remains in place over time.
To Stimulate Liquids in Model Building
Modelers frequently use epoxy resins to simulate water and other liquids. When the resin cures, it becomes shiny, hard, and durable, creating some interesting effects in the scene.
You’ve probably marveled at resin creations in various small scenes. Resins, for example, are commonly used in dollhouse miniatures to create glossy sauces on food, drinks, soups, raw eggs, or melted and spilled liquids.
Epoxy resins also produce great water effects in scale and railroad scenes. They’re relatively simple to work with if you recognize the material’s limitations and know how to handle it safely.
Choosing an Epoxy Adhesive
Strength Evaluation
The flexural, compressive, and tensile strengths of epoxy packaging are typically described in pounds per square inch (psi). Increased strength in one area frequently comes at the expense of another.
When choosing an epoxy, consider your top priorities:
- Focus on tensile strength if you’re concerned the bonded materials won’t come apart.
- Focus on flexural strength if you’re most concerned about the bonded materials’ ability to bend without breaking.
- Pay attention to compressive strength if you’re concerned with direct compressive resistance—that’s, how much pressure the epoxy can withstand when compressed from both ends. Squeezing the epoxy from both the bottom and top to see how many pressure pounds per square inch it can withstand before failing is the test.
Curing Periods
The time necessary for curing varies between two-part epoxies. This is the time it takes for the adhesive to harden, also known as its “work time” or “pot life.”
Short pot life is usually sufficient for small model building projects. You would like a longer work time for ones that necessitate more precision and may require adjustments and more time to tidy up any mistakes. Stronger epoxies typically cure more slowly.
Viscosity
A material’s viscosity measures how “flowy” it is. Molasses has a low viscosity compared to water. If you’re worried about the adhesive dripping while it’s setting, choose one with a high viscosity—one that isn’t too flowy.
Water Resistance
When hardened, most epoxies are waterproof, but some are made specifically to cure even when exposed to water. Choose a task-specific adhesive when repairing a hole in a tank or a leaking connection between pipes.