Why is epoxy surface cloudy or dull?

Epoxy resin reacts to the environment in which it is mixed/applied. Several factors can lead to a cloudy, milky, or translucent finish. These include small bubbles forming under the surface when used when the temperature is too cold. (Applying heat during curing may straighten this out.) Cloudy or dull epoxy is typically caused by excessive moisture. Specifically, moisture from excessive humidity in the area where the epoxy was applied or excessive moisture in/on the application surface. It can also be caused by moisture that has gotten directly into the epoxy mix, but this is a rare occurrence.

There are a few simple ways to avoid this issue:

  • Be sure to eliminate all water before applying the epoxy.
  • Never apply epoxy when relative humidity is over 75%

If you have an issue with cloudy epoxy, there are a couple of ways to correct it. Once the epoxy has fully cured, test the problem area with a water-moistened rage to see if the cloudiness can be “wet out”. If it works, wipe down the entire area. If the cloudiness cannot be wet out, you will need to lightly sand out the cloudiness and apply a thin seal pour.

  • Humidity

Do not work with resin if the humidity is above 75%. Make sure the mold is clean and completely dry before pouring.

  • Texture and Finish of the Mold

The mold can play a part in the finish. If the surface of your mold is shiny, the resin will be polished. This silicone mold is very matte; consequently, the resin turned out dull and matte.

  • The temperature of the Resin

The resin must be at the correct temperature for the correct finish. If it’s too cold, it can affect the finish.

To warm up resin, place the bottles of pre-mixed resin into warm water and let the resin warm up a tad before mixing. Do not heat it.

  • Dull After Sanding

If the resin has been sanded down, the finish will appear dull and scratched. Use lighter and lighter grit sandpaper until the finish is very smooth. However, It will still be cloudy.

  • Loads of Micro Air Bubbles*

* Aggressive mixing can whip the resin and add too many tiny bubbles into the resin.

* Mix slowly and completely.

If the resin mold is large on the inside but only has a small opening in the top, it can be hard for the bubbles to escape to the top.

If the item embedded into the resin has gaps and holes, the gaps make it hard for the bubbles to escape and result in a lot of bubbles.