How Long Do You Leave Epoxy Resin in the Mould?

How Long Do You Leave Epoxy Resin in the Mould?

Dec 30, 2023

If you're new to the realm of epoxy resin art, you might be curious about the ideal duration for leaving the resin in the mould before taking it out. The curing time can be influenced by factors like temperature, humidity, and the specific resin you're using. Generally, it requires a minimum curing time of 24 hours, but it is often recommended to leave it in the mould for at least 48 hours to allow for complete curing. In this blog, we'll delve into the recommended curing time for epoxy resin and offer valuable advice to guarantee a successful resin art venture. For those eager to attain a comprehensive understanding and excel in this fascinating craft, we suggest considering enrollment in a resin art course.

How Long Will Epoxy Resin Take to Cure?

Different epoxy formulations have varying cure rates, which directly affect the required duration for the resin to harden within the mould.

Fast Curing Epoxy Resin

It is specially formulated to dry quickly. It is ideal for small projects or when you are short on time. This type of resin usually cures within 24 hours, although it is always best to consult the instructions provided by the manufacturer to determine the exact curing time. This rapid curing time makes it an ideal choice for projects that require a speedy turnaround or for applications where time is of the essence.

Slow Curing Epoxy Resin

It is perfect for larger projects that require more time for the resin to settle and cure properly. The curing time can range from 48 to 72 hours. The extended time offers several benefits, especially when working on complex or large-scale projects. The slow curing process allows for better penetration and adhesion, resulting in a stronger bond and improved overall performance.

Factors Affecting the Curing Time of Epoxy Resin 

While the type of epoxy resin plays a significant role in determining the curing time, several other factors can affect the process as well.


Epoxy resin cures faster in warmer temperatures. If you are working in a colder environment, the curing time may be longer than expected. It is essential to maintain a temperature between 75°F and 85°F for optimal curing.

Pro Tip: If you need to speed up the curing process, you can place the epoxy resin in a warm environment or use a heat gun.


High levels of it can also prolong the curing time of the epoxy resin. Excessive moisture in the air can interfere with the curing process and result in a tacky or uneven finish. It is advisable to work in a dry and well-ventilated area.

Pro Tip: To ensure optimal curing in a high-humidity environment, use a dehumidifier or operate in a controlled environment with low humidity. When working in low-humidity conditions, consider using a humidifier to prevent rapid curing and potential cracking.


Thicker layers tend to take longer to cure as the heat generated during the curing process is retained within the resin. This is because the curing process relies on the chemical reaction between the resin and the hardener, which generates heat. Thicker layers inhibit the release of heat, slowing down the curing process.

Pro Tip: Instead of applying a single thick layer, consider dividing it into multiple pours. By allowing each layer to cure before applying the next, you can enhance the overall curing process and minimise the risk of uneven curing or heat build-up.

Catalysts and Fillers

Different catalysts have varying activation temperatures. Lower temperatures slow down the curing process, whereas higher temperatures speed it up. Certain fillers have a high surface area, which can absorb and trap the epoxy resin, delaying the curing process. In such cases, it may be necessary to increase the amount of catalyst or adjust the curing conditions to compensate for the extended curing time.

Pro Tip: The precise measurement of catalysts and fillers is crucial for achieving the desired curing time. Use a digital scale or graduated measuring containers for accuracy.

Heat Conductivity

The thermal conductivity of the mould material can impact the curing time. Molds with higher heat conductivity tend to facilitate faster resin curing. The rate at which heat is conducted through the resin affects the chemical reactions responsible for curing. Higher heat conductivity leads to faster curing, while lower heat conductivity results in a longer curing time.

Pro Tip: Applying external heat sources, such as heat lamps or specialised curing ovens, can help enhance heat conductivity.

Tips for Successful Curing of Epoxy Resin

To ensure a successful curing process and achieve the desired results, here are some valuable tips to keep in mind:

  • Start with Clean and Dry Surfaces: Before starting the curing process, it is crucial to ensure that both the mould and the material to be cast are clean and free from any contaminants. Dust, dirt, and moisture can interfere with the curing process and affect the final result.
  • Follow the Manufacturer's Instructions: Each epoxy resin brand may have slightly different curing requirements, so it is essential to read and follow the manufacturer's instructions carefully. This will ensure that you achieve the best possible results and prevent any mishaps during the curing process.
  • Use the Right Amount of Catalyst: Epoxy resin requires a precise ratio of resin to catalyst for proper curing. It is crucial to measure and mix the components accurately. Using too much or too little catalyst can lead to under-curing or over-curing, compromising the strength and performance of the cured resin.
  • Avoid Air Bubbles: This is a common issue when curing epoxy resin. They can weaken the final product and cause an uneven surface. To minimise the formation of air bubbles, it is recommended to pour the epoxy resin slowly and in thin layers. Alternatively, you can use a vacuum chamber or a heat gun to remove trapped air bubbles.
  • Ensure Proper Ventilation: While curing epoxy resin, it releases volatile organic compounds (VOCs) that can be harmful if inhaled in significant quantities. It is essential to work in a well-ventilated area or use appropriate respiratory protection. Additionally, avoid direct contact with the resin and wear gloves to protect your skin.

Read Also - What Are The Essential Raw Materials For Epoxy Resin Art?


Understanding the ideal curing time for epoxy resin is crucial for achieving professional-looking results in your resin art projects. Whether you are working with fast-curing or slow-curing resin, taking into account factors such as temperature, humidity, and thickness can significantly impact the overall curing process. By following the recommended tips and guidelines, you can confidently create beautiful resin art pieces that are sure to impress. So, next time you find yourself asking, "How long do you leave epoxy resin in the mould?" remember to consider the factors mentioned above and enjoy the rewarding process of working with epoxy resin. For more information and to explore our courses, visit Arts Shala’s website. You can also Contact Us for further details.

Back to blog