Why Is My Resin Cloudy? Discover 6 Causes of Cloudy Resin

If you've ever found yourself with cloudy resin and you're not sure what caused it, this blog is for you. Cloudiness can occur in both in liquid and cured resin, but the good news is that there's usually a clear explanation behind it.

In this article, I'm going to explore 6 common reasons why resin might become cloudy. I'll also explain how to prevent it and, when possible, how to fix it for crystal-clear results.

Understanding The Resin Curing Process

First, let's get back to basics. Epoxy resin start with two liquid parts: a resin and a hardener. When the resin and hardener are properly measured, mixed and allowed to cure in ideal conditions, they undergo a chemical reaction and transform from a liquid into a solid. The result is a resin that's strong, hard, glossy, and clear.

However, if certain conditions aren't met, a variety of issues can result including sticky resin, bendy resin, a greasy film on the surface, and ... you guessed it ... cloudy resin. 

Common Causes of Cloudy Resin - Liquid

1. Cold Temperatures

Resin colder than standard room temperature has a cloudy, milky appearance once mixed due to thousands of cold-induced micro bubbles. You'll never be able torch these micro bubbles out - believe me, I've tried. Cold resin also has a thick, taffy-like consistency, which makes it difficult to pour, mix, and spread.

To prevent cold-induced cloudiness in resin: 

• Use the product at standard room temperature or slightly warmer (no lower than 23ºC / 72ºF and no warmer than 30ºC / 85ºF.)
  
  
• If the resin is colder than the recommended range, place the tightly sealed bottles in a warm water bath to bring it up to temperature before measuring and mixing. This is really important!  If you place mixed resin and hardener in a water bath, the warm temperatures will prompt it to flash cure.
  
  
• Store tightly sealed resin and hardener bottles at room temperature.

2. Under Mixing

When you first mix the resin and hardener, you'll notice cloudy streaks as the two parts combine.  This is totally normal, and after the recommended mixing time, these streaks should no longer be visible. But if the resin is under-mixed, not only will these cloudy streaks remain, but you'll likely end up with sticky resin as well.

3. Whipping The Resin 

It's important to stir the resin and hardener thoroughly for at least 3 minutes to ensure a proper cure. While mixing the resin, it can be tempting to beat or whip it, but this will create a cloudy, frothy looking resin, with far more bubbles than necessary.

Common Causes of Cloudy Resin - Cured

4. Matte Silicone Mold

5. Moisture 

• Paint, glue, or sealant on the substrate that hasn't fully dried
• Wet inclusions in the resin, such as flowers or leaves
• Contamination from water through wet tools or drips from a warm water bath
• Moisture in the surrounding air as the resin cures

To prevent cloudiness caused by moisture, make sure all your materials and tools are completely dry before introducing them to resin. 

Unfortunately, once cloudiness from moisture appears, it's very difficult to fix because it's usually deep within the resin layer. 

In these cases, the only option worth trying is to carefully sand down as much of the affected resin layer as you can, followed by pouring a fresh coat of resin. Be aware that you may not be able to remove all of the cloudy resin, and you could damage the artwork below.

💡 TIP: To learn more, see our blog How Does Moisture Affect Epoxy Resin?

6. Humidity

• Maintain a consistent temperature and humidity levels below 80%, and preferably at 50%

• Use air conditioning to help reduce humidity
  
  
• If you live in a highly humid climate, run a dehumidifier the day before you plan to resin

• If a dehumidifier or air conditioning are not an option, avoid working with resin in rainy or humid weather
  
  
  

Amine blush must be removed before attempting to apply a fresh coat of resin. Here are the steps:

1. Amine blush film clogs sandpaper, so remove it by wiping the resin surface with a soft cloth and warm, soapy water made with a grease-fighting dish soap such as Dawn. The sticky amines are water soluble and should wipe away easily. Allow to dry and inspect for any remaining residue.
   
   
2. If the film remains, you will need to wipe with something more abrasive like a Scotch-Brite pad. Allow the surface to dry completely and inspect: the scouring pad will likely have scuffed the resin surface and you will need to apply a fresh coat of resin. 
   
   
3. Use coarse sandpaper to rough up the cured resin surface, wipe away sanding debris with a clean, damp cloth, and pour a fresh coat of carefully measured and mixed ArtResin to restore the clarity.  Cover and allow it to cure.
   
   

 💡 To learn more, see our blog How Does Hot Weather Affect Resin?

6 Expert Tips To Prevent Cloudiness in Resin

For a clear and glossy resin finish, follow these best practices:

These preventive measures will significantly reduce the chance of cloudy surfaces in your resin projects.

Fixing Cloudy Resin After Curing

If you encounter cloudiness despite taking precautions, try these methods:

1. Sand and Re-Pour: Sand out the affected resin layer as best you can without damaging the artwork below it and pour a fresh resin coat on top.
   
   
2. Sand and Polish: Gently sand the surface and use a polishing compound to restore clarity and shine.
   
   

Unfortunately, fixing cloudy resin may require multiple attempts or you may need to start over altogether, depending on the underlying causes and how deep the cloudiness is. Practice and experience will help you master the art of resin curing.