Discoloring of Polyester Resin: Causes and Solutions

Discoloring of Polyester Resin: Causes and Solutions

Are you experiencing discoloration of your polyester resin projects? Don't worry, you're not alone! Many crafters and DIY enthusiasts encounter this issue, but the good news is that there are solutions available. In this article, we will explore the causes of discoloration in polyester resin and provide practical tips to help you avoid this problem in your future projects.

What Causes Discoloration of Polyester Resin?

There are several factors that can contribute to the discoloration of polyester resin. One common cause is exposure to UV light, which can cause the resin to yellow over time. Another factor is improper mixing of the resin and hardener, which can result in uneven curing and discoloration. Additionally, contaminants such as dust, dirt, or moisture can also lead to discoloration in your resin projects.

How to Prevent Discoloration

To prevent discoloration of your polyester resin projects, follow these tips:

  1. Use UV-resistant resin: When working on projects that will be exposed to sunlight, opt for a UV-resistant resin to prevent yellowing. Eparency polyester is a nonyellowing cutting edge resin.

  2. Mix the resin properly: Make sure to follow the manufacturer's instructions carefully when mixing the resin and hardener. Proper mixing is essential for achieving a clear and consistent finish.

  3. Avoid contaminants: Keep your work area clean and free of dust, dirt, and moisture to prevent contaminants from affecting the color of your resin.

  4. Store resin properly: Store your resin in a cool, dry place away from direct sunlight to maintain its clarity and color.

Common Questions about Polyester Resin Discoloration

Why is my resin turning yellow?

Resin turning yellow is a common issue caused by exposure to UV light. To prevent yellowing, use a UV-resistant resin or protect your finished projects from direct sunlight.

How can I fix discolored resin?

If your resin has already discolored, you can try sanding and polishing the surface to remove the yellowing. Alternatively, you can cover the discolored areas with another layer of clear resin to restore the color.

Can moisture cause discoloration in resin?

Yes, moisture can lead to discoloration in resin projects. Make sure to keep your work area dry and free of moisture to prevent this issue.


By understanding the causes of discoloration in polyester resin and following the tips provided in this article, you can prevent this issue in your future projects. Remember to use UV-resistant resin, mix the resin properly, avoid contaminants, and store your resin correctly to achieve beautiful and long-lasting results. Happy crafting!

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