There are so many different epoxies out there and so much to know about how they work. You may be curious about how long epoxies take to cure, if they can stand up to heat, how they compare to other popular resins, what the difference between one-part and two-part epoxies is, and what to do if your epoxy does not cure properly. Why don’t we look at some facts about epoxy that may address your questions?
How Long Does Epoxy Take to Cure?
This is a broad question, since there are so many different types of epoxies. Some can cure in as little as an hour. Most epoxy you would use on your flooring or other construction needs takes 72 hours to fully cure. It is important to note that this means you should do a second coating of epoxy within 24 – 48 hours of the first coat to allow full chemical bonding. The cooler it is in the area you are using epoxy, the longer it will take to cure. Whatever epoxy you choose to use, be sure to read the manufacturer’s instructions so you fully understand how long it will need to fully cure.
What Is the Difference Between Epoxy and Polyester Resins?
Polyester resins are what are commonly used when coating a surfboard. Much like epoxy, they offer an amazing shiny finish. Where they differ is that they are toxic in nature. They cost less than epoxy does, but they also are more porous so offer less protection. Polyester resin only bonds well to itself, unlike epoxy, which can bond with almost any surface. Polyester resins also are unable to be used on polystyrene foam because they will dissolve it, while epoxy has no problem being used on polystyrene foam. This is because most epoxies are solvent-free.
Is Epoxy Heat Resistant?
Epoxy is not fully heat resistant. For instance, you could not use it in a fireplace. Epoxy can stand up to heats around 140 degrees Fahrenheit. After that, it can begin to melt. Once the heat is removed, it can harden again. If it is vertical, this can present a problem. You should not use epoxy anywhere that will be exposed to temperatures over 140 degrees Fahrenheit.
One-Part Epoxy Resins
One-part epoxy resin cures by the curing agent, which is in the main agents, reacting to heat and curing. This means that heat is required for proper curing. Since it is one-part, it is easy to manage, as there is no mixing of two different parts. Also, since you do not have to use a hardener, there is less chance of you damaging your skin. One-part epoxy has a higher resistance to heat as well. It does not cure well when laid too thickly.
Two-Part Epoxy Resins
With two-part epoxy, the curing process does not begin until the two parts are mixed together. This means that once mixed, you have a short period of time before it hardens too much to work with it. Two-part epoxy cures at room temperature. It does require precise measuring of the two agents to properly use it. The hardener can also cause your skin to be irritated if it comes in contact with it.
What If Epoxy Doesn’t Cure?
If you are using one-part epoxy that doesn’t seem to be curing, try to apply more heat. It is possible that you did not heat it enough to cause it to have the chemical reaction it needs to harden. If that does not work, you will have to scrape the epoxy off and start again.
For two-part epoxy there are many reasons it may not have cured properly. If you do not mix it at the proper ratios, it will not cure. Using utensils that are wet or dirty can also affect your epoxies curing. Epoxy cannot come into contact with water during its curing time. Also, while two-part epoxy does not need heat to cure, temperatures can affect curing times. It may be that it just needs more time.
If your epoxy just will not harden, you will have to scrape it off, sand it down and start again. Fortunately, it is easy to get your epoxy to cure properly every time just by following simple instructions on the label of the specific epoxy product you are using.