During an epoxy project, it's important to maintain several environmental conditions in an effort to achieve a perfect finish. Among these are temperature, humidity, and general cleanliness (e.g., minimal dust, debris, etc.).
Most users understand the temperature aspect, which gets put front and center in nearly every epoxy's instructions set. And cleanliness itself is somewhat obvious, as it prevents substances from getting stuck inside the finish before the epoxy has had time to cure.
But fewer users are mindful of ambient humidity levels, which, when high, can often lead to a marred epoxy finish or failure to cure. On top of that, many creators who encounter this issue don't realize why, leading to a reoccurrence during subsequent epoxy attempts.
In this article, we'll discuss the reasons for maintaining low humidity during an epoxy project, as well as how to do so, and why it might run high in the first place.

Why does controlling humidity matter during an epoxy project?
Hight humidity (and other sources of moisture) can interfere with the epoxy's curing process, which begins immediately upon mixing both components (resin and hardener).
There are several reasons for why a low humidity matters, listed below.
- The ability to fully cure.
- Stopping the formation of air bubbles
- Avoiding cloudiness in your epoxy.
- Stopping moisture by condensation
- Ensuring a high level of strength in the final finish.
Achieve a flawless finish by using UltraClear Epoxy
Regardless of how well you apply your epoxy finish, it can only ever be as good as the product you choose allows, which is why you should avoid low-cost budget brands that sacrifice quality and even your safety for a cheaper upfront price. For a truly resilient, long-lasting finish with a flawless appearance, UltraClear has you covered.
Not only are our UltraClear Epoxy resins 100% made in the USA, but they're also designed to last a minimum of 7 years, with a crystal-clear transparency that can be highly customized through colorants, embedments, and other means of creative expression.
You'll find out premium resins on the following pages:
- UltraClear Bar & Table Top Epoxy—Our strongest resin for long-lasting, durable finishes on bar tops, countertops, tables, and more.
- UltraClear Deep Pour Epoxy—A deep casting resin that supports extra thick layers of up to 2 inches without an increased risk of bubbles and other issues.
- UltraClear Art & Craft Epoxy—Our specialty art epoxy, designed for creative endeavors that require more nuance.
Next, we'll take a closer look at each of the reasons mentioned above.
Reason #1: The epoxy's ability to fully cure
Epoxy requires a specific humidity range for optimal curing. High humidity levels—generally 60% or above—can interfere with the chemical reactions necessary for the epoxy to harden properly.
If the humidity is too high, it can lead to incomplete curing, resulting in a sticky or soft surface. And because epoxy is so strong and adhesive, it can be very difficult to mend this issue after the fact, though quite possible.

Reason #2: Stopping the formation of air bubbles
With any epoxy pour, there's a risk of air bubbles. Often, these form when air is pushed out of porous surfaces by the epoxy coating, which then attempts to make its way to the surface for release; that's why we recommend a seal coating before applying a flood coating for any project.
A second possible source of air bubbles comes from air induction during the mixing of an epoxy batch. Using high force or spinning a drill bit too close to the surface can cause air to be pulled directly into the epoxy mixture, generating air bubbles that then try to escape through the viscous epoxy substance.
Fortunately, both of these issues can be mitigated by using a heat gun or torch after pouring the epoxy, but it becomes more difficult to do so if there's high humidity, as moisture in the air can create conditions that make it difficult for the epoxy to release trapped air, leading to a bubbly or flawed surface.
Reason #3: Avoiding cloudiness in your epoxy
Most high-quality epoxies take about 3 full days to cure to a hardened, usable state. During this time, the epoxy is particularly vulnerable to environmental changes, especially temperature swings and increases in humidity.
In some cases, curing epoxy in a humid environment can cause it to finish with a murky or cloudy appearance. Moisture can become trapped within the epoxy as it cures, which affects its clarity and appearance. This cosmetic issue can cause an otherwise beautiful finish to be an eyesore.

Reason #4: Preventing moisture from condensation
Humidity can increase the risk of condensation forming on surfaces, which can contaminate the epoxy batch/coating. Any moisture on the substrate or within the mixing containers can prevent proper adhesion and affect the overall finish of the project.
More generally, it's a good idea to always use a dry, clean container for mixing up an epoxy batch. Reusing containers can be a source of moisture and residual epoxy that can cause problems.
Reason #5: Ensuring a high-strength final finish
High humidity can also indirectly compromise the strength and durability of epoxy once it has finished curing. Epoxy that cures in high-humidity conditions may not achieve its intended properties, leading to issues like brittleness or reduced impact and scratch resistance.
For best results, it’s recommended to work in a controlled environment where humidity levels are kept below 60% and temperatures are maintained at a stable range, ideally around 75°F. This helps ensure proper curing and the best performance of the epoxy.

What are common causes of high humidity?
When high humidity is present in an epoxy project environment, it tends to be the result of various natural or human-made factors. Here are some relevant causes that might affect your project:
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Weather Conditions:
- Warm air: Warm air holds more moisture than cold air. In humid climates, high temperatures can lead to increased humidity levels.
- Rain and storms: Precipitation can increase humidity in the atmosphere, especially after rain or thunderstorms. This effect occurs more quickly in warmer environments, which facilitate faster evaporation.
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Poor Ventilation:
- Closed spaces: Rooms without adequate airflow can trap moisture, raising humidity levels.
- Inadequate HVAC systems: Poor heating, ventilation, and air conditioning (HVAC) systems can fail to regulate indoor humidity properly.

How to reduce humidity in your epoxy workspace
At this point, we've discussed various sources of humidity, as well as the epoxy-related issues caused by it. Now, let's go over some factors and practical methods that may help lower humidity levels:
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Dehumidifiers: A portable dehumidifier is an easy way to actively remove moisture from the air. Choose one that suits the size of your crafting space.
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Air conditioning: If your crafting space has air conditioning, keep it running. AC units help remove humidity while cooling the air.
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Proper ventilation: If your humidity is higher inside than out, you can open windows and doors to create cross-ventilation. Use fans to circulate air, which can help reduce humidity. You can also install or use exhaust fans to remove moist air.
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Moisture absorbers: Some users prefer to use desiccants. Consider placing moisture-absorbing materials such as silica gel, activated charcoal, or baking soda in your crafting space to help absorb excess moisture.
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Seal windows and doors: Ensure windows and doors are sealed properly to prevent humid air from entering. Use weather stripping or caulk to close gaps.
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Proper insulation: Insulating walls and ceilings can help maintain a stable temperature and reduce humidity levels, especially in basements or garages.
Additional Resources
Here are some additional resources you may find useful:
- How to prepare wood for an epoxy finish—Our guide to preparing wooden surfaces for an epoxy coating.
- What to know about epoxy before starting a project—New to epoxy? Read this guide for expert advice on getting started.
- How does water affect epoxy? Is it waterproof?—Wondering how cured epoxy fares with moisture and humidity? Check out this explainer.
UltraClear Epoxy: Resin products of unmatched quality
As with any material, epoxy resin has both pros and cons. But no other sealant has so few weaknesses, and that's what puts epoxy above all other options when it comes to being a finish for high-traffic fixtures and furniture such as countertops, table tops, and bar tops. And among epoxy resin products, there are none that match the quality of UltraClear.
You can find our UltraClear Epoxy products on the following pages:
- UltraClear Bar & Table Top Epoxy: The classic choice for bar tops, countertops, and table tops. Rock-solid, waterproof, and crystal-clear.
- UltraClear Deep Pour Epoxy: Our deep pour casting resin. Ideal for thick layers, such as those needed for river tables.
- UltraClear Art & Craft Epoxy: Our arts and crafts resin, designed for smaller artistic endeavors which typically involve resin molds and require a bit more fluidity than bar top epoxy.
Epoxies that endure, with minimal upkeep
With high chemical and physical resistance, UltraClear resins can withstand and endure many forms of wear and tear without breaking a sweat or showcasing any cosmetic damage.
Plus, in addition to its ease of application, they also require little upkeep to maintain its pristine appearance. With a high-quality epoxy finish, you can expect a minimum lifespan of 7 years, with no need for reapplication. Beyond that, it's a breeze to renew that coating, requiring only a light sanding and a fresh layer of epoxy.
Expert support from our resin specialists
For more information about epoxy, or for assistance with your epoxy project, contact us at UltraClear Epoxy, where you can speak with one of our epoxy experts. During business hours, you can also text chat online with one of our resin specialists by clicking the Help button at the bottom of your screen.