There is a lot of debate surrounding the hardness of epoxy resin.
Some people swear by its durability, while others claim it’s not as tough as they’d like.
So, does epoxy resin dry hard? The answer to that question is a little complicated.
Let’s take a closer look at what makes epoxy resin so unique and how it dries in order to get a better understanding.
Does epoxy resin harden on its own?
Epoxy resin will start to harden as soon as the two components are mixed together, but it can also be helped along with a catalyst.
There are many different types of catalysis, but most involve adding an accelerant to the mixture that will speed up the drying process.
This is usually in the form of an activator or hardener, which comes in either liquid or solid form.
The choice of hardener will depend on the type of epoxy resin being used, so always follow the manufacturer’s instructions.
Table of Contents
- Does epoxy resin harden on its own?
- Does epoxy fully harden?
- Why is my resin not hard?
- How long does epoxy resin dry for?
- Can you dry epoxy with a hairdryer?
- How do you soften hard resin?
- Why is my resin still bendy?
- Why does epoxy take so long to dry?
- Is epoxy resin hard or soft?
- Why is my epoxy resin still soft?
- Why is my resin still soft after 24 hours?
Does epoxy fully harden?
Epoxy resin does not fully harden. Even after epoxy has cured, it will still be softer than a block of wood.
It is possible to sand and scrapes off the top layer of your finished product to give you a smoother more polished finish but even then there are still ridges that can be felt if you run your hand across the surface.
The reason for this is because when epoxy starts curing its molecules link up together forming long chains which are called polymers.
When these polymers crosslink with each other they form an interlocking network of chemical bonds creating what we call plastic or polymerized plastic.
This process takes time (usually hours) and during that period heat energy escapes from inside the material some shrinkage occurs but is not enough to noticeably affect the final product.
Why is my resin not hard?
If your resin is not hard, it could be due to a number of factors. The most popular are:
– Not enough catalyst (hardener) was added and the mixture did not fully cure, or too much catalyst was added causing excess heat during curing and subsequent partial catalyzation.
If this occurs, do not try to work around it by adding more resin! You will only make things worse.
Instead, remove all uncured material from your project with alcohol or acetone before attempting another batch using proper amounts of both components.
See What if my epoxy doesn’t dry? for detailed instructions on how to clean up spilled/unmixed product that hasn’t cured yet so you can start fresh.
– Ambient temperature was too low (below 65°F/18°C) or too high (above 85°F/29.44°C).
Epoxy resin cures best at room temperature, so if your conditions are not ideal, you may need to wait until the weather is more cooperative or use a heat gun or oven to speed up the process.
– Poor surface preparation allowed air bubbles to form under the coating which inhibited proper curing.
Make sure all surfaces are clean and free of oils, dust, and other contaminants before applying epoxy resin.
See Surface Preparation for more tips.
– The mixture was applied in too thick of a layer causing it to cure slowly and unevenly.
Thin coats will dry faster and more consistently than thick ones. Apply multiple thin coats instead of trying to get the job done with a single, heavy application.
– The mixture was not stirred thoroughly enough before pouring or brushing onto your project surface; this can cause air bubbles in the epoxy that prevent it from curing properly.
Mix for at least two minutes (longer if you’re using colored pigment) until there are no streaks left and all ingredients are blended together well.
How long does epoxy resin dry for?
The resin should be touch-dry in 24 hours. You can give it a light sand and then polish it after 72 hours before applying another coat.
Once the epoxy resin is completely dry, you’ll have a beautiful glossy finish.
Can you dry epoxy with a hairdryer?
How do you soften hard resin?
You can also use a rag soaked in acetone instead of placing it all in a container.
Leave overnight for best results. With only a few exceptions, most resins will dissolve when exposed to acetone vapor.
Why is my resin still bendy?
If your resin is still bendy, it hasn’t fully cured. This can happen when you don’t mix the resin and hardener properly – make sure to stir thoroughly! Resin that isn’t fully cured won’t have its full strength.
You can try putting it in a warm oven (around 100 degrees Fahrenheit) to help speed up curing time, but it may compromise the quality of your piece if there are any areas that haven’t been exposed to heat long enough for them to cure.
Why does epoxy take so long to dry?
Epoxy doesn’t dry like paint. It cures, which means it changes from a liquid to a solid through a chemical process.
The amount of time it takes for epoxy to harden depends on several factors, including the thickness of your project and the ambient temperature in your workspace.
Is epoxy resin hard or soft?
Epoxy resin can be quite hard after it dries, but there are also formulations that remain relatively soft.
It all depends on the ingredients used and the curing process. In general, epoxies become harder over time as they cure.
This makes them an ideal choice for many applications where a durable, rigid finish is required.
Why is my epoxy resin still soft?
If your epoxy resin is still soft after it has cured, this may be because it was not mixed properly or because of an issue with the substrate.
Make sure that you are following all of the instructions for mixing correctly, and check to see if there are any problems with the surface where you are applying the epoxy resin.
If there is a problem with either of these, it will not allow the epoxy resin to cure properly and will result in a soft finish.
Why is my resin still soft after 24 hours?
If you can get to a warm spot (75 degrees Fahrenheit), place your piece somewhere warm for a few hours or overnight and see if that helps!
To speed up curing in future projects, I recommend adding an extra drop of hardener per ounce of resin used to help the chemical reaction along. This will also ensure optimal hardness once cured.