Why Epoxy Gets Cloudy And What To Do About It


Working with epoxy resin is thoroughly rewarding most of the time but occasionally things go wrong. One thing that often worries a first-timer is when their epoxy goes cloudy, fortunately, this isn’t a disaster and we’ll show you exactly how you can overcome this problem and get your epoxy looking great again. 

So, here’s why epoxy gets cloudy and what to do about it? There are two causes of cloudiness: moisture and bubbles. You can cure moisture cloudiness by wetting out the resin or sanding and recoating. With bubbles, you can heat the surface or the bottles, mix slowly, give the mixing time to expel air, stir bubbles out of the mix, blow on the resin, use a toothpick, work in thin layers, use a vacuum chamber and sand and recoat. 

Of course, there are some nuances that go into this. Below I’ll explore what the differences are between the moisture issues and the bubble issues – and how to fix them. 

The Clouds In Your Epoxy Resin Might Be Tiny Bubbles

You won’t believe it but there are two different ways that epoxy resin can end up looking cloudy or milky in appearance. 

You can end up with tiny “micro-bubbles” that have formed in the resin during periods of low temperature. 

There’s also the possibility that there’s too much moisture in your epoxy resin – this isn’t normally because you’ve added water to your resin but rather it’s absorbed water either from the air or from the surface that you’re applying it to.

There’s not much you can do about the temperature, though as you will see, you can try to fix the problem of bubbles after the fact or you can simply wait until it’s warm enough while you use the resin.

You can, however, take preventative steps to stop water from clouding your resin – you can, firstly, ensure there is no water on the surfaces you are working on and that they are as dry as possible and, secondly, never use epoxy when the humidity outside is 75% or higher. 

How To Fix Cloudy Epoxy Resin

As we said at the beginning there are two causes of cloudy epoxy resin and we’ll tackle each, in turn, starting with moisture. 

When The Cause Is Moisture

There are only two real ways to tackle too much moisture in your epoxy resin:

Try To “Wet Out” The Resin

This doesn’t mean add more water but rather take a slightly damp rag and apply it to the cured epoxy resin. You may find that a bit of pressure can help shift the moisture at this point if it can – you can wipe down the whole area and see the cloudiness disappear

Sand And Recoat The Resin

If that fails and you can’t leave the epoxy in its cloudy state, then you may need to lightly sand the epoxy until the cloudiness disappears and then add a single light layer of epoxy over the top to bring the finish back

When The Cause Is Bubbles

If you’ve got bubbles clouding your epoxy, you should be able to see the bubbles in the resin. Hopefully, you will notice the problem before you start to use it but if not – you may be able to fix the problem without sanding. 

Gently Heat The Surface Of The Resin With A Cigarette Lighter

OK, this tip requires a lot of patience to make it work properly. You need to understand that while it works – a flame will quickly burn or tarnish the resin itself and that’s no better than having bubbles. 

So, take a cigarette lighter and light it then run the flame gently over the surface of the resin. You don’t want any part of the resin exposed for much longer than a second or two. You can have multiple visits to any part of the resin with the lighter, but you need to let it cool first. 

So, our approach would be 1 application of 1-2 seconds. Then wait a few minutes. Then another application of 1-2 seconds. And so on… until the bubbles are gone.

Note: If you overheat epoxy resin then it can end up going soft and won’t cure properly for months. So, not only do you want to avoid burns – you don’t want to do this either. 

Put The Resin In A Bowl Of Warm Water

OK, we can’t stress this enough but if your resin has not yet been applied, you can always submerge it in warm water. However, it must be warm – you cannot use hot water for this, or you’ll create further problems.

Alternatively, you could set up a space heater on low heat and place the bottles (including the hardener) about 2-3 feet away from it – enough for them to get warm but not enough to catch fire. 

The bubbles should simply rise to the top of each bottle and pop. Once they’re gone, they’re gone.

Combine Your Resin And The Hardener Very Slowly

You can add your own bubbles to the resin if you’re too vigorous about mixing the resin and the hardener together. So, just be chill when you put the two bottles in the same container – stir slowly and casually. 

It ought to take about 5 minutes to mix the two fully together, any faster and you might be stirring in some air which is going to be a problem. This is especially true if the room and/or the bottles are already a little on the chilly side. 

Wait Once You’ve Put The Hardener With The Resin

Even when you’ve taken your time over mixing, it’s a good idea just to let the epoxy resin sit for about 5 minutes after you’ve done. If there are any bubbles that have sneaked into the resin while you were mixing, they ought to gently rise to the top of the mixture and pop themselves in the air. 

However, you should be aware that this is going to steal some of the “pot time” for your resin. That is the length of time which you can work with the epoxy resin before it becomes too hard to use – so read up on the “pot time” (it should be on the label or the manufacturer’s website because it differs between brands of resin) and take this into account. 

Stir The Mixture Slowly Trying To Bring Bubbles To The Surface

If, after all this, you’re still finding bubbles in the mix, you can gently try to stir them towards the top and see if they will surface and pop by themselves. 

Blow On Your Resin (Use A Straw)

If you have a straw to hand and you’ve applied the epoxy in a thin(ish) layer then you can try using a straw to blow on the surface and see if it will help you pop any bubbles that have appeared after application.

We know that some people prefer to work with a mask when they use epoxy, you can skip this tip if you don’t want to take your mask off. 

Toothpicks Can Help

The most stubborn bubbles tend to form right at the edges of where you lay your epoxy down and that means you’re going to find that they resist most of the other tricks for de-bubbling your mix. 

Never mind, there’s another weapon in your arsenal. The good old fashioned toothpick. You can try and pop the bubble directly with your toothpick or move it away from the edges – so that you can grab your trusty straw and start blowing again. 

Toothpicks are very good for removing bubbles and are possibly the greatest weapon you have to get rid of them. 

Apply Resin In Very Thin Layers

It’s not always possible but if the job allows you to use thin layers of epoxy resin, it’s very hard for bubbles to remain in these layers. It’s also easier to remove (with a straw and/or toothpick) any bubbles that do form.

However, if this isn’t practical and is likely to leave you with a bunch of useless resin rather than a finished project, don’t do it

Vacuum/Compression Chamber Use

If you use epoxy resin for jewelry you might also try using a vacuum or compression chamber if you have one on hand. Sealing the piece or the resin in the chamber will help draw bubbles to the surface.

However, if you don’t already have such a device – we don’t recommend buying one. Not only are they quite expensive but there are some safety issues with using these devices and you really need proper training before you get into using them. 

Sand And Recoat The Resin

Finally, if all else fails and the end result still has too many bubbles and too much of a cloudy appearance, you can always sand the resin off and then recoat it. We know, it’s a pain but sometimes we have to be gracious in defeat and just go back to basics.

Conclusion

OK, so now you know why epoxy gets cloudy and what to do about it. It’s a bit of a pain to deal with, that’s for sure, but it’s not an insurmountable problem and there’s something quite fulfilling about rescuing a project that you thought wasn’t going to turn out perfectly, at first. 

Jedediah Arnold

Jedediah has been working with epoxy resin for a couple of years. When he started, he wanted to share everything he learned as he learned it which continues.

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