Heat-resistant epoxy can endure extreme temperatures up to 600° Fahrenheit, depending on the manufacturer and product. Once it is fully cured, you can safely place hot pans, cups, plates and bowls on top of it. However, never place a hot pan or skillet directly from the stove on the epoxy. It is recommended to use proper padding or placemats for your pans to extend the lifespan of your epoxy. Generally, epoxies can withstand cooler temperatures relatively well, and can even tolerate temperatures below freezing.
However, most epoxy resins will start to soften at 140-150° F, but will harden again if the temperature drops. Heat-resistant epoxy can come in several variations. While a DIY epoxy kit will typically only withstand temperatures up to 150 degrees, there are other epoxies that can endure extreme heat up to 600 degrees. These are specially formulated with fillers such as quartz, and offer resistance to abrasion and cure at high temperatures. The chemical reaction between resin and hardener as the epoxy cures will generate heat.
This uncontrolled heat buildup is called an uncontrolled exotherm. Out-of-control epoxy heating can foam, smoke, emit hazardous fumes, and generate enough heat to melt your container or cause nearby items to catch fire. The heat-resistant epoxy resin has been formulated for industrial applications, but can also be used for larger projects, such as kitchen countertops. Since part of the curing process is a chemical reaction that causes heat, too cold resin may have trouble curing properly. While it is recommended to use a lower temperature environment for your work, a higher temperature environment also helps dry the resin once applied, by heating the room or area in which your project is located. These are active and aggressive epoxies that can withstand shocks, prolonged vibrations and extreme heat.
When the base epoxy resin and the hardener (curing agent) are mixed, a chemical reaction occurs that causes them to heat up. Because these epoxies are thermally conductive, they are fantastic for encapsulation and potting, as well as providing exceptional chemical resistance and resisting exposure to vapor. The best heat-resistant epoxy can withstand temperatures up to 600 degrees Fahrenheit thanks to the fillers and reinforcements added in the resin. Carbon fiber-reinforced epoxy composites can withstand significantly high temperatures (up to 1500 degrees Celsius), making them valuable for aircraft components. For a basic DIY epoxy resin project of small size it will be able to withstand low heat temperatures between 68 and 195 degrees Fahrenheit, anything higher and it will start to warp or soften. Even at room temperature, if the relative humidity is constantly in the region of 95%, epoxy resins could swell and become less solid.
The most common epoxy resin that is usually used for DIY projects and small jobs can only withstand a minimal amount of heat and is not specifically high-temperature epoxy.