One of the things you have to understand when working with epoxy is how long it takes to dry or cure. After mixing epoxy resin with a hardener, a chain of chemical reactions starts that takes it from its liquid state to solid-state. Several factors affect the cure time and set time of epoxy. For instance, the type of resin used affects the cure time.
The terms epoxy set time and cure time are used interchangeably, but they are different terms. In this article, you will learn the difference between both terms. Also, it will discuss other aspects of epoxy set time and cure time you need to know for your project.
What is Epoxy Set Time?
The epoxy set time is the initial cure stage. It is the time between mixing the two-part epoxy until it turns into a semi-solid or gel stage. The epoxy has not reached a full cure at this stage and so can’t withstand pressure.
What is Epoxy Cure Time?
Epoxy cure time is the final stage of the cure time. It is the time between mixing the two-part epoxy until it’s fully dry. At this point, the chemical reaction is complete. It can withstand full temperature, chemical resistance, and has reached its full strength. It’s advisable to allow the epoxy to reach its maximum cure time before you proceed to the next stage.
Stages of Epoxy Cure Time
To better understand the epoxy set time and cure time, you need to understand the different stages of epoxy dry time.
a. Liquid State or Open Time
This is the stage after mixing the resin and the hardener. The epoxy chemical reaction kicks in at this stage. The mixture is in a liquid and workable state at this stage. You apply the liquid at this stage. Also, assembly and clamping should be handled at this stage to enable the mix bond better. In other words, it’s during the open time you open, mix, apply, smooth, shape, assemble and clamp the mixture.
b. Initial Cure or Set Time
This stage is also known as the green stage. The first stage of epoxy chemical reaction kicks in at this point and the mix is partially cured. It’s in gel form and can leave a dent when you touch it. Also, at this stage, you can add a new layer to coat the surface without further preparations, but can’t work on the initial mixture.
c. Final Cure or Epoxy Cure Time
As mentioned, this is the final cure stage. The epoxy has dried and turned to a solid-state because the epoxy chemical reaction is complete. You can remove the clamps at this point because the project has reached its full strength. It can withstand chemical resistance and full temperature. It is after the cure time that you sand or progress to the next stage of the project.
Factors That Affect Epoxy Cure Time
Two main factors affect epoxy cure time. That is the temperature and the hardener used. We will explain both concepts below and how it affects epoxy cure time.
a. Epoxy Temperature
An epoxy chemical reaction is essential in epoxy cure time. Heat speeds up the chemical reaction and in turn fastens cure time. The temperature is determined by exothermic temperature and ambient temperature.
Exothermic temperature is the heat produced as epoxy undergoes a chemical reaction during the curing process. The amount of heat produced during this process depends on the thickness of the mixture. The thicker the epoxy mixture, the more heat is produced and retained and the faster the cure time.
Ambient temperature has to do with the temperature of the air. The hotter the air, the faster the mixture will cure. Also, the temperature of the surface the epoxy is exposed to counts as the ambient temperature. For instance, if epoxy is applied on a warm or hot surface, it cures faster.
b. Epoxy Hardener (buy from amazon)
There are different brands of epoxy hardeners out there and each brand has an ideal temperature cure range. You use the Pot life to determine the cure speed of a particular hardener. The pot life is measured by the cure speed time of a volume of epoxy. Thus the pot life is usually shorter than the open time. The general rule is to choose a hardener that gives you adequate work time.
How To Speed Up Epoxy Cure Time?
It’s advisable to allow epoxy enough time to cure. But if you are working on a limited timeframe, there are some steps you can take to speed up cure time.
a. Use a Fast-Curing Resin
Using a fast-curing resin will speed up the curing time. Fast-curing resins come with curing agents that facilitate quick drying time. It starts to cure minutes after you pour the epoxy. The good thing is that your project gets to dry faster and allows you to proceed to the next stage.
The downside is that you have little or no time to correct mistakes made while pouring and shaping. That is why first-time users should not use the fast-curing resin.
b. Increase Temperature In The Room
We’ve mentioned that ambient air plays a role to hasten epoxy cure time. Increasing the temperature in the room as you work will speed up the cure rate.
c. Use UV Resin
If you have a UV lamp, you can use a UV resin and get it cured in minutes. Note that the product can’t be cast in thick layers.
d. Warm Surface Materials
Exposing epoxy to warm or hot surface materials can speed up the cure time. For instance, using warm water to work. Another option is to use a hairdryer or heat gun to dry the surface. Ensure that you dry the surface evenly to avoid bubbles and cracks.
How Do You Know When Epoxy Is Cured?
You know that epoxy is cured when the surface is dried. Also, when you stick your finger on the surface, it won’t leave a dent. At this point, you can remove the clamps and proceed to the next stage of your project.