Skip to content

Understanding How Humidity Affects Epoxy During Application

Controlling the environment during an epoxy installation is key to ensuring a successful pour. Understanding the effects that humidity has on epoxy can mean the difference between a flawless application and an unsatisfying cure.

In this article, we will explore how water vapour can interfere with epoxy applications, whether epoxy can cure in a hot and humid climate, the effects of humidity on epoxy, and the ideal temperature for epoxy resin to cure.

What is humidity?

Humidity is a measure of the concentration of water vapour in the atmosphere. The more water vapour that there is present in the air, the higher the humidity will be. Usually, higher temperatures allow for higher humidity levels.

While higher temperatures may seem ideal for the curing of epoxy resin, allowing too much moisture to accumulate in the air can have undesired effects on the final finish. If temperature and humidity levels are not maintained for the curing process, the product may produce a cloudy finish or an oily surface layer.

There are several ways to control the humidity in your work environment. One of these is to use air conditioning (avoid using evaporative cooling as this produces moisture). However, in an extremely humid location, using a dehumidifier a day before can provide benefits.

Epoxy and humidity: What are the effects?

So, how exactly does humidity affect epoxy applications and how will you know? It is not unusual for epoxy to show no signs that it has suffered from excess moisture until it cures. To ensure that a clear finish is produced, humidity levels will need to be controlled while pouring and curing.

If the epoxy has been exposed to uncontrolled conditions, the surface layer may appear to have “amid blushing.” It can also produce an oily, sticky, or waxy appearance if it is subjected to changing temperatures and high humidity. Maintaining a consistent temperature throughout the curing process is very important when avoiding similar condensation issues. Water in the air can cause epoxy to foam or undergo an exothermic reaction, resulting in a premature cure.

Is epoxy still capable of curing in hot weather? In short, yes. Generally speaking, warmer temperatures speed curing, but as with anything, too much of a good thing can lead to negative outcomes. The same is true when curing epoxy.

The following factors will help you understand what will contribute to epoxy’s temperature:

  • You should keep your work environment at an ambient temperature of 22 – 25ºC.
  • You should also consider the surface temperature where epoxy was applied (another aspect of the ambient temperature).
  • The heat that is generated by epoxy curing, or exothermic heat.
  • When epoxy resin is left for long periods of time in a confined space, it cures faster. This means if the epoxy mixture is left inside buckets or mixing containers for too long it could be subjected to aggressive exothermic reactions.
  • Measuring must be precise. Exothermic reactions can occur when Part A (Resin) is mixed with Part B (Hardener) in an incorrect ratio.
  • You should use more than 10% of the pigment additive ratio in your mixture. It is important to note that some pigment additives are not compatible with some epoxy products and may accelerate the curing process if used.

Epoxy Cure Stages

Epoxy resin surfaces are the result of a chemical reaction which occurs when Part A (resin) and Part B (hardener) are mixed together, transforming the mixture into solids. This period of transformation is referred to as the cure time. During this curing process, about halfway through, the epoxy shifts from a liquid state to a gel state, followed by solidification.

Here are the phases of cure that epoxy goes through:

1. Open Time (Liquid Stage)

This is the working time. After mixing, the epoxy mixture remains a liquid, providing the opportunity for you to finalise your project and ensure a dependable bond. It is vital that this time is used to finish your project.

2. Curing Phase (Gel Stage)

Once this phase has been reached, the epoxy has begun curing and can no longer be worked on. The mixture will begin heating up and eventually develop a gel state and become non-sticky.

When the epoxy is this far along in the curing process, it may still be sticky like masking tape. In other words, it occurs when two layers make a primary or chemical bond.

3. Final Cure Phase (Solid Stage)

The final stage of the epoxy curing process is the solid stage. After this, it is possible to dry sand the surface.

The epoxy will be at its maximum strength once this point has been reached. This means that applying a new layer of epoxy will not form a primary bond. To achieve a stable mechanical or secondary bond, it will first need to be cleaned, dried, and lightly sanded.

Once this new mixture has been cured for several days, it can last up to two weeks before it becomes an inert solid.

Choosing The Right Temperature For Curing Epoxy

Maintaining a controlled environment is the best way to ensure a successful epoxy project. The right temperature must be achieved, regardless of the installation location. It is of utmost importance that your materials are kept in a maintained environment. It is essential that these steps are followed. Failing to do so, could cause air bubbles, cloudy finishes, or wet spots in the final product.

The purpose of these requirements is to prevent epoxy-curing problems. After spending all your time and energy, you do not want such an unsatisfactory result.

Following the instructions below will help you achieve a perfect epoxy cure.

Curing Epoxy At The Proper Temperature

  • Prior to using epoxy, ensure the room and the product don’t drop below 22°C until it has begun to cure (72 hours).
  • Before mixing epoxy, allow it to acclimate to the right temperature if it is being received outdoors in temperatures below 22°C.
  • In situations where the temperature has fallen below freezing, we recommended recruiting the use of small heaters with thermostats to achieve a suitable temperature in the room. If the thermostat is not 100% accurate, it is advisable to set the temperature to a few degrees warmer than the recommended temperature.

Curing Temperature Limit For Epoxy

  • It is best if the temperature stays close to 25°C.
  • Exceeding the recommended temperature is better than going below when attempting to maintain a stable climate.
  • Temperatures should not exceed 32°C nor fall below 15°C.
  • In warmer temperatures, the epoxy reacts faster, resulting in a shorter mixing time, faster cure time, and faster finishing results.

How To Minimise Epoxy Adverse Effects By Controlling Humidity

  • Epoxy must be prepared in a dry environment.
  • Keep the humidity below 80% as much as possible.
  • The location where the epoxy is stored must also be under the correct conditions. Ensure that there is no excess dew present to avoid inconsistent results in working procedures.
  • While mixing epoxy, make sure to keep away any wetness.


No matter your experience in the industry, having this craft under your belt has many advantages. Making sure that your projects all go smoothly is something every installer strives for. To assist this, we provide guidance and high-performance products and materials so that you can accomplish this.

Our experts share these tips before you begin your epoxy project:

  • In order to help manage the ambient temperature in your workplace, set up a working air conditioner or heater.
  • The humidity in the workspace can be controlled with the help of a working dehumidifier.
  • The room can be cooled to minimise humidity, but it may take longer to cure. Make adjustments as needed.
  • Take note of the atmosphere at work. A hot summer can bring unwelcome levels of humidity.

Related posts

0 0 votes
Article Rating
Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x






Get a quote