Have you decided to paint your garage, bathroom, or patio? Or are you up for a fun, creative project to express your artistry? Whatever you are up to, epoxy paint is an excellent choice as it is both affordable and durable.
And the most important part is that it looks amazing! You might have already finished your project and wondering—or you are just curious to know beforehand—how long does epoxy paint take to dry? After all, this is one of the most asked questions when it comes to painting on epoxy resin.
In this piece, we will cover every detail. From the time taken to finish curing to how it functions and how to cure it faster- you will get to know everything so that you can be stress-free and confident about your project.
How Long Does Epoxy Paint Take to Dry: Complete Guide
How Do Epoxies Function?
If you already have some exposure to epoxies used for painting and how they work, you should already know that they come in two containers. One of those contains resin, while the other one contains the hardener. That’s why they got the name two-part epoxy.
Now, one of the silliest things a first-time user can assume is that the use of more hardener translates to quick and better curing. And believe me when I say this, one cannot be more mistaken.
What you need to know is, epoxies don’t set or dry like usual adhesive glues. Rather they cure over time. You may ask, “What exactly is the difference? They do sound the same, don’t they?” And that is a perfectly reasonable question.
What Makes Epoxies So Unique?
When we are talking about normal adhesives or glues, these chemical compounds emit solvents to solidify, which is the drying process you observe. But when we are talking about epoxies, they cure by thermosetting chemical reactions.
What this means is that when the molecules of the resin or base of the first container are mixed up with the complimentary molecules of the hardener of the second container, a chemical reaction is triggered.
In this reaction, these molecules enthusiastically join hands with each other, and the whole thing starts to harden/cure.
Why Maintaining a Perfect Mixing Ratio Is So Crucial?
Think of it as making a water molecule (H2O). You need two hydrogen atoms and an oxygen atom to make a molecule of water. Adding more hydrogen or oxygen with disregard to the ratio will simply result in leftovers. And the situation can be very tricky when the leftover is the epoxy’s hardener.
That’s why you need to mix the resin and the hardener in perfect ratios as per the instruction given by your epoxy manufacturer.
Terminologies You Should Know
When it comes to dealing with epoxies, you should know the different phases of curing. This will help you in better understanding the whole procedure.
After you mix the epoxy resin with the hardener in due proportions, you get a pretty tight window before the thickening reaction starts in full motion. This is the phase where the mixture is fully in a liquid state. For most two-part epoxies, this window lasts for about 20 minutes to 30 minutes.
In whatever way you plan on using your epoxies, you have to do it before this period ends. Because when it starts to get sticky, working with the gel will become very difficult.
As we were saying, you need to complete your painting before this phase. Gel time is after the pot life when you will observe the epoxy starting to thicken. In this phase, trying to steer the gel or any sort of movement of the epoxy object is not recommended. Both have the potential of disfiguring and ruining your project.
This phase is also known as ‘Handling Time.’ This is because the mixture will gradually progress from a tacky gel consistency to that of hardened rubber. During this period, you can delicately maneuver the epoxy paint, and you can remove clamps or bracings in case you use it.
If it is a painting on your floor or wall, then there is nothing to worry about. The time for a green cure can vary. It can take from a single hour to a full day, depending on the type of epoxy that is used.
Major chemical reactions of curing are usually completed by this stage. The painting becomes fully prepared for dry sanding. You can expect the chemical bonds to reach about 90% of their full strength.
As for the rest 10%, it will depend on room temperature and continue to cure. This phase lasts for a couple of days, presumably up to 7.
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Understanding the Curing Duration
As you can see, there are several stages before the epoxy fully sets in. And two things have a direct effect on the duration of these stages:
- Hardener speed
- Room temperature
You may find in the instruction manual that the pot life is 30 minutes at 25-degree Celsius room temperature or something similar to that. What this means is, you get 30 minutes for mixing, application, smoothing, shaping, or assembling before the hardener starts to react and become solid from liquid.
This is important because you may get less than 25 minutes if your room temperature is above the 25-degree Celsius mark. Heat pushes the hardener to react faster. Thus, higher room temperature means lower pot life.
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How to Speed Up the Curing Process?
Using Different Hardeners
As you can already tell, the only two ways of speeding up the curing process are using a different hardener and increasing the room temperature.
Now, if you are not an expert in the technical aspects of epoxy resins, using a different hardener in the hope of reducing curing duration is highly discouraged.
And even if you do, do contact the manufacturer first. Even though the base formula is pretty much the same, hardeners from different brands can contain or lack compounds that don’t suit your resin. Better to be safe than sorry.
The best way to make the epoxy paint dry faster would be to increase room temperature. After you are finished with the painting part, applying supplemental heat can decrease curing time substantially. You can use a hot air gun, a heat lamp or any other safe heat source after the epoxy mixture is applied.
Considering a small batch, approximately 50 grams to 150 grams of the mixture, every 10 degrees increase in temperature will result in the curing time cut in half.
That means, if the quoted gel time is 30 minutes for 25 degrees, it will decrease to 15 minutes at 35-degree Celsius room temperature. The reverse also applies. If the temperature gets down to 15 degrees, it may take an hour to gel properly.
You can also cast the mixture layers thicker. This will also result in increased heat and temperature because of the exothermic process. We will discuss this in the next section.
In a nutshell, applying heat and increasing the temperature can be a great option for you if you desire a quick cure. But if you plan to do it, you must do so moderately because too much heat can be problematic and sometimes cause risky situations.
The Technical Difficulty of Increasing Heat: Exotherm
You already know that heat speeds up the reactions, which result in fast curing. But there is a catch. Increasing temperature can be a double-edged sword. The nature of this curing reaction is such that it will produce heat during the bonding. This is called exothermic heat.
On the one hand, the created exothermic heat speeds up the reaction even more, which causes more heat, and this chain of events goes on until the bonding reaction is almost over.
But on the other hand, with more heat, the ambient temperature will continue to rise, and if it rises above a certain level, there can be a risk of accidents.
Precautions and Adequate Measures
So, how do you deal with the problem of overheating? Well, you allow the exothermic heat to easily dissipate before letting it heat the surroundings too much.
As you can guess, doing this will slow down the reaction a bit. But nothing comes before safety, right? You need to make sure that the clamping or bracing is not made of insulating material.
Also, keep in mind that several inches of an epoxy layer in thickness can produce enough heat that can melt a plastic cup. So, even if you try to make the paint thicker for faster results, don’t make it more than half an inch.
All these things may sound a little dangerous but fear not. These are all extreme cases that should not usually occur in your regular epoxy painting. If you maintain caution and go as per the instruction, then you have nothing to worry about.
So, how long does take epoxy paint to dry?
Tl: DR; You can easily go at it after a day. But for a safe bet and an assured mind, give it a week.
Handling epoxies can be a bit tricky at times. The drying time will vary on the formulation and heat. And you can manipulate them both to get it dry in a shorter time. But manipulation and modification come with their own complications.