Epoxy resin can be used for a lot of different things from gluing items to making jewelry with it. But it is still a little bit hard for beginners to wrap their heads around what epoxy actually is. I had the same issue when I started working with epoxy. So let´s start with one of the most pressing questions for newcomers, is epoxy resin hard or soft?
As a whole, epoxy is hard when it is fully cured. Before it cures epoxy will be either liquid or kneadable. Once it has fully cured epoxy will on average be about as hard as red maple wood but it is easier to work with in general. But some epoxy resins can become twice as hard as concrete once cures.
Epoxy is a type of plastic so it will behave differently than wood when you saw or sand it and it is generally easier to work with because it is synthetic.
How Hard Is Epoxy?
There are a lot of different types of resins like UV-resin, deep pour resins, art resins, and so on and each type can also be composed differently. And each of these resins has different hardness scales. But how hard is epoxy on average?
Epoxy is generally as hard as red maple wood which has a Janka Hardness scale of 1450. Certain types of epoxy resins are even harder than that such as resin used for flooring, and other resins that are softer than that, like UV resins.
The Janka Hardness Scale is a scale for the hardness of wood. You can read more about it on this Wikipedia site.
But I found it a nice comparison for the hardness of epoxy resin because everyone knows how hard different wood types are. So is epoxy resin harder than wood?
As a whole, epoxy resin is harder than most types of wood. It is generally harder than cedar but softer than walnut wood. But depending on the kind of epoxy resin the resin can also be much harder than that or softer.
Can Epoxy Resin be Flexible?
I did some tests to see how flexible epoxy resin is. I tested the flexibility of UV-ren, art resin, and deep pour resin, and here is what I found out.
As a whole, epoxy resin is not flexible once it is fully cured except when it is very thin (less tha 1mm). Resin will be slightly flexible when it is not completely cured yet. If the epoxy resin was not correctly mixed with the hardener then the resin might cure incorrectly resulting in a flexible piece of resin.
For testing the flexibility of resin I poured very thin layers of resin on a silicone matt and let them cure.
Thick resin is generally very rigid and can´t be bent at all but thin resin casts can be bent quite significantly.
In my tests, I found out that thin UV resin is the most flexible. I was able to almost fold it completely before it broke.
Deep pour resin was the least flexible overall and art resin was pretty flexible but it broke once I bent it to around 90°.
There are instances where your finished resin cast might be flexible or easy to deform. This can be for three reasons. Either you did not mix the resin with the hardener in the correct ratio or your resin isn´t cured fully yet, or your resin is expired.
So if your resin is still flexible or sticky then the best thing you can do is leave it to cure for another 24 hours. If that didn´t lep then you have to do the thing again.
But before you do, check the expiration date of the resin. If it is expired get some new resin and try again.