What Temperature Should You Apply Epoxy?

Epoxy application can strengthen and fortify a surface. The material can act as a shield against dirt and water damage and protect floors from wear and tear. But for all of these benefits to apply, one has to coat the subject in epoxy at the right temperature, so it receives equal coverage and the coat cures as intended.

You should apply epoxy at a minimum surface temperature of 50 F and a maximum of 85F. The epoxy doesn’t spread evenly below this temperature range and can lack aesthetic appeal and structural integrity if cured at a temperature above 85F. One should avoid applying epoxy in winter.

The rest of this article covers all you need to know before trying to apply epoxy on a cold surface or in cold weather, including whether you can apply epoxy without temperature regulation and what happens if the area gets too cold or hot after the coat has been applied. You will also learn how to test how well the epoxy has cured and what it costs to keep an area warm for properly applying and curing epoxy.

Can I Apply Epoxy in Cold Weather?

The first thing anyone learns when pouring or applying epoxy resin, primer, or sealant is that the material requires a high temperature. Of all forms of epoxy products for home improvement and art projects, epoxy resin is the least conducive to colder temperatures. When one says “applying” epoxy, the term isn’t used for pouring resin over a canvas, though. It usually refers to applying a primer or an epoxy coat.

You can apply epoxy in cold weather as long as the surface you intend to coat is sufficiently warm. The heat must be maintained during the application and must be gradually lowered, ensuring that the epoxy cures in a stable manner. A sudden drop in temperature before the epoxy has cured prevents the coat from bonding with the surface it covers.

Whether epoxy is applied on a cold surface or the surface turns cold rapidly right after application, the effect is the same. The curing process is interrupted. In some casing, the coat remains perpetually uncured, staying dry to touch but not hard enough to be functional. If the epoxy is applied to seal a surface, the cold temperature will keep it from hardening to the point of being a reliable shield.

“Cold” and “hot” aren’t binary, though. If the surface temperature drops but not too significantly, the epoxy will harden eventually. The issues that come with longer curing time will all be liabilities worth considering. Some of the problems that come with a ‘mildly cold’ environment in an epoxy application project are.

  • Imperfections incurred by soft epoxy – When the epoxy hasn’t hardened, it cannot act as a solid. Dust and other particles can get embedded in its surface, making the otherwise glossy coat somewhat cloudy. This isn’t a problem if your sole reason for using epoxy is practical surface protection.
  • The integrity of epoxy – If the epoxy hasn’t cured by the time it comes under pressure, the project can fall apart. This risk is more serious when the epoxy is being used to hold two materials together. For floor coating, the integrity of the epoxy still matters, but the project doesn’t get ruined as long as the area remains unused.
  • Uneven curing – When the temperature isn’t regulated and is mildly cold, chances are there are no artificial controls in place to ensure that the coated surface has an even temperature. In the absence of surface heating, spot-heating occurs where certain regions (for a variety of reasons) become warmer than others. This leads to unevenness in how the epoxy cures.

Resin and Cold Weather – What to Expect

Having discussed the implications of letting the epoxy cure in cold weather, let’s explore what applying epoxy means once the project is over. For this section to apply, you would need to regulate the temperature of the surface while applying epoxy resin and as it cures. After the resin has solidified to the desired consistency, it will not be at the risk of cracking.

Epoxy does not crack in the cold, but the surface on which the coat is applied might crack. Coats of epoxy are most commonly used over concrete floors. Extreme heat and cold can contract and expand concrete, which cannot be held together by epoxy.

As a consequence of this, the epoxy coat is torn apart by the surface it is bonded to. In case you apply the same coat over a surface that doesn’t crack, the epoxy will be fine. It is one of the most resilient surface coating products and can withstand extreme cold and significant heat without cracking or warping.

Heating for Epoxy Application

Now that you know you won’t have to worry about temperature once the epoxy is applied and cured to the desired effect, you might be ready to move ahead with the epoxy application. As mentioned earlier, you’ll need to regulate the temperature during the course of the project. Let’s take the example of a detached garage to explore how you can make an environment hot enough for epoxy application.

To heat your garage floor for epoxy coating, you must use floor heating. If no native heating system is in place, room heaters can be used with the importance of surface heat in mind. It doesn’t matter if the garage air is hot. The floor’s temperature should not be low.

This brings up the question of epoxy application outdoors. If you have floor heating, you can coat interior floors with epoxy. Even when floor heating is absent, you can use space heating to apply epoxy properly. But what do you do outside?

Epoxy is not good for outdoor application in areas that remain cold around the year. You can apply epoxy outdoors in states that get enough sun in the summer. Once the epoxy has cured, it can withstand extreme cold, but it is the curing process that requires a lot of heat.

In other words, if the epoxy is applied to an object like a lawn decor item, and it is transferred outdoors after the epoxy has cured, the temperature isn’t going to be an issue. Ironically, epoxy is better for cold weather than hot weather once cured. While normal heat doesn’t impact epoxy, if the temperature is raised significantly, the epoxy resin might turn into mush.

Curing epoxy in the cold is where things get tricky, but it is definitely possible to do so at low temperatures as well. It will just take longer, and during that period, you have to shield the coated surface from dust particles and high impact, at least until the surface is dry to touch. After that, you don’t have to worry as much but must still be careful.

It can take 72 hours for the epoxy to cure in cold weather. During this period, you should lock the room in which the coat is applied. Children should be kept away from it, and no pets should be allowed in the room. You must keep checking on the epoxy every 12 hours until you’re sure it has cured.

Now you might wonder how you would know if the epoxy has cured in the first place. It can be tricky because once a layer of epoxy is dry to touch, you might not know how strong it is. Given that epoxy is often used for professional coats, and professionals don’t leave things to chance, you can be confident that there is a step-by-step process you can follow to ensure the coat is properly cured.

  1. When pouring epoxy (or applying it), coat a test surface away from the project.
  2. Make sure the materials match (both the coated area and the test surface feature the same material like concrete)
  3. Ensure similar tempratures. If the test surface and project surface are in the same room, you don’t have to worry about this.
  4. Wait up to the curing time indicated by the manufacturer – This is usually between 24 and 48 hours, depending on the hardener used.
  5. Add another 24 hours for colder weather – If the surface isn’t as hot as the working temperature of the epoxy requires, you must wait another 24 hours. Skip this step unless you’re in a colder region.
  6. Try to dent the test surface epoxy with your nail – Use your nail to dig into the epoxy applied over the test surface. If you can dent it, wait another 12 hours and try again. In most cases, you won’t be able to dent it, though.
  7. Try to dent the project surface with your nail – Now that you’re sure that the epoxy has cured, it is time to test the work surface. Usually, you won’t be able to dent the epoxy with your nail. The only exception is if the test surface and the project surface do not match in material or temperature. Wait 12 hours and try again if you can dent the surface with your nail.

Throughout the above testing procedure, the temperature of the environment was supposed to be consistent across both the test surface and the actual project surface. This doesn’t usually require any controls since the project will cure at room temperature.

Epoxy Curing: Temprature Talk

Epoxy can (and often does) cure at room temperature. Most guidelines, manufacturer instructions, and online resources that recommend 24 to 48 hours waiting period often assume that the project cures at room temperature. You can speed up or slow down this process by tweaking the surface heat.

While epoxy can be cured at room temperature, it cannot be poured in similar conditions. The higher temperature required to pour epoxy resin is called its working temperature. Not all epoxy projects require similarly high working temperatures, though. Epoxy primers, for instance, can be applied at a relatively neutral temperature.

The working temperature conundrum brings us to the interesting question of the project’s feasibility. If you’re looking for the temperature at which you should apply epoxy, you probably already have the epoxy you want to coat a specific surface with. Here’s how much it will cost to sufficiently heat the project environment.

You need to heat the work surface to 50 F. If you use an air heater, you might need to get the room to 80 F just for the floor to reach a 50 F temperature. The cost of heating a standard garage to 50 F and 80 F respectively can be calculated by the electricity consumed by space heaters and floor heating in each context.

It costs $7 to run a floor heater and bring the surface temperature of the ground to the ideal epoxy application range. If you recreate the same effect by using a space heater, then it will cost you $12.60 over the span of a single night. Considering 48 hours of proper heating, you might pay $25.02

The above conclusion rests on standard gas and electricity cost estimates. If your private provider charges more or less, the amount you pay will obviously vary. As a rule of thumb, applying epoxy in summers is cheaper, but in winters, the floor heating is usually running anyway, and the extra cost of the slight increase in temperature isn’t a lot. Applying epoxy is feasible in most cases regardless of the season.

You might waste more money running coats of epoxy than heating the subject for epoxy application. Make sure that you don’t assume dry to tough equals ready to use. Always wait 24 hours before even testing the epoxy cure. If the coat can be applied indoors, bringing the project into a smaller space helps as the working environment can be brought to the working temperature quickly.

Final Thoughts

Applying epoxy doesn’t mean sitting in a boiling hot room. Temperatures north of a sunny summer in a coastal city are all you need for the proper application of an epoxy coat. It costs $14 to $24.02 to bring surfaces to this temperature using floor heating or a space heater, which means you can apply epoxy in cold weather as long as you can bring the subject’s temperature up to 50F.

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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