Resin Getting Hot — Is This Normal?

large epoxy resin pour

Working with epoxy resin can be anything from a fascinating hobby to a lucrative business. But, if you are just beginning in your resin venture, you might be wondering about a few basics. For example, should your epoxy resin be getting hot when you pour it?

Epoxy resin heats up once poured and mixed with a hardening agent as the two components seamlessly combine via an exothermic reaction (producing heat of up to 400℉). While normal, it is important to maintain an appropriate temperature range and curing time according to your product specifications.

If, when pouring your epoxy resin, you begin to notice that the resing is exceeding the temperature range suggested with your specific product (or the curing time seems off), it will be important to attempt to cool off the substance to avoid smoking. You can do this via fans or by transporting the curing epoxy to a cool area. Let’s take a closer look at the ins and outs of the exothermic reaction that results in hot resin.

What Does it Mean When Your Resin Gets Hot?

Whether you are using resin to pour a beautiful, intricate piece of jewelry, or you are using it for a gorgeous river table to blow your friends and family away, you will need to make sure that you follow the product recommendations when mixing the resin with the hardening agent as it begins to cure. This will inevitably mean that your resin will become hot due to the exothermic reaction taking place.

The exothermic reaction that takes place when you pour resin indicates that the product is functioning as it was intended- melding perfectly with the hardening agent as it cures. When it becomes too hot, though, it can begin to smoke or can even crack, so it is important to monitor the curing process.

This means that if you see your resin growing hot (even hot enough to melt off a foam container), then the appropriate reaction is taking place in order for the hardening agent to combine with the resin and form the product you are intending to create. Still, this does not mean that there are no limits when it comes to the amount of heat that should be produced by your resin.

Specifically, while there are many different temperature variations and curing time recommendations, most resins will fall under a pretty standard range of temperatures that should not be exceeded during the curing process. Often, the temperature ranges will fall between 250-350℉, yet some resins can reach up to 400℉ and still maintain their product integrity.

Of course, monitoring this can be a bit difficult as you will want to avoid interfering with the curing resin as much as possible. Still, there can be some tell-tale signs that your resin is overheating including bubbles beginning to form, smoking, or the product cracking as the top and bottom portion are not maintaining even heat distribution.

What Happens if Resin Gets Too Hot?

After investing countless hours in preparation for your next epoxy project, you want to make sure that you take all of the appropriate precautions to ensure a successful pour. Not only will you have spent time and energy researching the procedures, but you will have invested resources into the epoxy, hardening agent, and any other supplies like wood, molds, and beyond. But, once you have poured, if the resin becomes too hot, are you out of luck?

When resin becomes too hot (such as when a torch is not being carefully used to reduce the bubbles or you have poured over the recommended amount), it can crack due to the temperature differential, begin to smoke, or can even catch fire.

Fortunately for you, there are plenty of ways to work with the epoxy resin as its temperature becomes noticeably too hot. However, you will want to be highly proactive on this considering there are some mistakes that are not fixable. Still, even if your worst nightmare is coming true and you have noticed a large crack in your resin due to overheating, there are still ways that you can mend this project. It will take lots of time and energy, sure, but it can still be worth it if you are working with a gorgeous piece of wood, for example.

There are some mistakes that cannot be fixed when your resin becomes too hot though including if the resin is allowed to smoke for too long. This could take place if you were to desist in monitoring the resin during the curing process. 

For this reason, it is important to maintain frequent check-ins on your curing epoxy, especially when you are new to the process or trying out a new brand or product that you have not worked with yet. Not all types of resins are made equal, so it is important to ensure that you have poured an adequate (not too much or little) resin with the hardening agent as you await a beautiful cure.

Also mentioned above, using a blowtorch is a common practice when working with resin. If you are noticing that there are many bubbles forming on the surface of your freshly-poured resin, you can carefully use a blowtorch to increase the pressure and pop the bubble before it becomes a permanent fixture in your pour (or at least before the resin hardens and then you have to sand it down to remove the bubble). 

However, using a blowtorch with resin must be done with extreme caution. Considering there is already an exothermic reaction taking place that causes the resin to heat up before it hardens, applying additional heat to the surface should be done in extreme moderation and in following the recommendations of the product details. Otherwise, this “convenient” trick could result in catastrophic blows to your entire project.

How to Prevent Resin from Getting Too Hot?

So, at this point, you can recognize that it is entirely normal for resin to become hot during the curing process (because of the exothermic reaction taking place). Still, you want to follow the product recommendations to ensure that the resin does not reach temperatures outside of its recommended range. Are there effective ways to prevent the resin from becoming too hot?

To prevent resin from getting too hot, consider the following: use the recommendations from the product description in terms of environmental temperature, pour depth, container size, and pouring instructions. Then, avoid heating the resin before pouring and use caution when heating after the pour.

Let’s take a closer look.

Use the recommendations from the product description.

Not all resins are made the same, and if you are used to using one type of resin and then switch to a different brand, you might be surprised at the differences that you find. This can include how deep you can pour the epoxy in each layer as well as the recommended environmental temperature range to keep the epoxy in storage, while pouring, during the curing process, and upon completion. Read the directions. It can save you big time.

Use an appropriately sized container.

Using a container that is both sized appropriately for your project and for the type of resin that you are using is incredibly important in preventing your resin from overheating. Be sure that the container you are using follows the recommended depth for your resin as well as meeting the other dimensions for use with wood or another type of material.

Pour more, thinner layers.

When in doubt, it is better to pour your resin in thinner layers and have to repeat the process a few more times than it is to pour over the recommended depth. Not only will your resin have a better shot at hardening appropriately when you follow the appropriate pour recommendation, but it will also be less likely to overheat and crack.

Use a deep pour resin.

If you are anything like me, and you enjoy the satisfaction of watching your project come to life more quickly, then you should opt for a deep pour resin. This type of product will allow you to pour fewer, deeper layers of resin on your project without as great of a risk of overheating. Using the right types of products for your project is an investment worth considering.

Avoid heating the resin and hardener mixture before pouring.

Some people like to moderately heat up their resin and hardening agent mixture before beginning the pouring process as they say this helps to reduce the formation of bubbles. However, this is a risky move considering this additional heat added prior to the curing process can actually cause harm to the overall process. Instead, carefully use alternative methods for, say, reducing the bubbles as they form once the product has been poured and begins to cure.

Use moderate amounts of coloring pigments.

Adding different types of coloring pigment products to your resin mixture can actually throw off the balance of the components. This can mean that the excessive use of mica powder pigments, for example, in your resin and hardening agent mixture could slightly disrupt the reaction that will take place during the cure. To avoid this causing your resin to heat up excessively, simply use high-quality pigments and use a moderate amount for coloring your resin.

Work in a cool environment.

Going back to product recommendations, be sure to follow the appropriate temperature range for pouring the resin you are using. You will find a common range of 70-80℉, but I have poured at slightly lower than this range due to the natural environment where I live, and I have never had an issue. While you will need the area you are working in not to be too much colder than the recommended range, you definitely do not want it to be hotter.

Add fans before or during the curing process.

If you are noticing that the resin is beginning to overheat (or beginning to smoke), or you are working in an environment that is warmer than the recommended temperature range for your product, you can carefully place fans in your workspace to reduce the temperature. Just be sure that the fans are aimed appropriately so as to not stir up dust and other particles that could ruin the clean surface of your resin if they were to land in your pour.

Damien Madeira

Damien has been doing woodworking for the last 5 years. He began as a hobbyist with hand tools and slowly worked his way up to own larger machines and mill rough wood into beautiful creations. While still considering himself a hobbyist, he has a passion for woodworking and enjoys working with epoxy as well.

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