Why Epoxy Resin Turns Yellow and What You Can Do About It

One of the biggest concerns people have with epoxy is yellowing over time. A project can look crystal clear at first, then slowly start to shift in colour as it ages. This is especially frustrating when the look of the epoxy is a major part of the finished piece.

This guide explains why epoxy turns yellow, what makes yellowing more noticeable, and how to reduce the risk when working on river tables, serving boards, top coats, mould pours, and other epoxy woodworking projects.

Why Does Epoxy Turn Yellow?

Epoxy can turn yellow as it ages because the material changes over time when exposed to light, heat, and environmental conditions. Some products resist yellowing better than others, but yellowing is still one of the most common long-term concerns with clear epoxy projects.

In many woodworking projects, the yellowing becomes most noticeable when the epoxy was originally very clear, very light in colour, or placed somewhere with regular sunlight exposure.

The Most Common Causes of Epoxy Yellowing

1. UV Exposure

Sunlight and UV exposure are some of the biggest reasons epoxy starts to yellow. Projects near windows, in bright rooms, or in spaces with heavy natural light are more likely to show this change over time.

2. Age and Normal Material Change

Even without extreme sunlight, epoxy can change with age. Some yellowing is simply part of how certain resin systems behave over time.

3. Heat and Environmental Conditions

Heat can also contribute to epoxy ageing and discolouration. Projects exposed to warmer conditions may show changes faster than projects kept in more controlled environments.

4. Product Chemistry

Not all epoxy products are built the same way. Some are designed with better UV resistance or better suitability for exposed surface applications, while others are more focused on deep casting performance. Ecopoxy products are designed with UV inhibitors for a better long term visual appearance.

• EcoPoxy FlowCast
• EcoPoxy FlowCast SPR
• EcoPoxy UVPoxy
• Deep Pour vs. Top Coat Epoxy

5. Clear and Light-Coloured Projects Show It More

Yellowing is usually easier to see in crystal-clear epoxy, white-tinted projects, and very light pours. Darker pigments or stronger colour effects can make small changes less noticeable.

Where Yellowing Usually Shows Up Most

River Tables

River tables often use large clear or lightly tinted epoxy sections, which can make yellowing easier to notice over time, especially in bright rooms.

Top Coats

Surface coats can show yellowing because they sit directly on the exposed face of the project and often receive more direct light.

Serving Boards and Decorative Projects

Smaller projects can still show yellowing, especially when the design relies on clear resin or high contrast between the epoxy and the wood.

Mould and Display Pieces

Any decorative cast object or moulded piece that depends on visual clarity can show yellowing more obviously than a darker or more heavily pigmented project.

How to Reduce the Risk of Yellowing

Choose the Right Epoxy for the Application

Product choice matters. Some epoxy products are better suited for exposed surface use, while others are built mainly for deep casting applications. Matching the product to the actual job is one of the best places to start.

Be Realistic About Sunlight Exposure

If the finished project will live in a bright room or near direct sunlight, it is smart to expect a higher risk of visible yellowing over time. That does not always mean you should avoid epoxy, but it does mean the design and product choice matter more.

Think Carefully About Clear vs Coloured Resin

If long-term clarity is a major concern, the design itself matters. Clear resin usually shows yellowing more than darker or more heavily pigmented epoxy.

• Read Best Pigments for Epoxy
• Shop Liquid Pigments
• Shop Black Diamond Pigments
• Shop Squid Ink Pigments

Match the Project to the Space

A clear epoxy showpiece in a sun-filled room will usually face a different long-term reality than a darker epoxy project in a more controlled indoor space.

Does All Epoxy Turn Yellow Eventually?

Many epoxy systems can yellow to some degree over time, but not all projects will show it at the same speed or in the same way. The product, the environment, the amount of UV exposure, and the design of the project all influence how noticeable the change becomes.

That is why the better question is often not whether yellowing is possible, but how visible it is likely to be in the specific project you are building.

Projects Where Yellowing Matters Most

• Clear river tables
• Light or white-tinted epoxy pours
• Glossy exposed top coats
• Decorative castings meant to stay crystal clear
• Projects that live in bright rooms or near sunlight

Helpful Products and Guides

• EcoPoxy FlowCast
• EcoPoxy FlowCast SPR
• EcoPoxy UVPoxy
• Shop All Resin + Epoxy
• Epoxy Resin Guide for Beginners
• Epoxy for Woodworking
• Deep Pour vs. Top Coat Epoxy
• Why Epoxy Gets Bubbles

Frequently Asked Questions

Why does epoxy turn yellow?

Epoxy can turn yellow over time because of UV exposure, age, heat, product chemistry, and environmental conditions.

Can sunlight make epoxy yellow?

Yes. Sunlight and UV exposure are some of the most common reasons epoxy starts to yellow.

Does all epoxy turn yellow eventually?

Many epoxy products can yellow to some degree over time, but the speed and severity vary depending on the product and the conditions.

Can you prevent epoxy from turning yellow?

You may not be able to eliminate yellowing completely, but you can often reduce the risk by choosing the right product, reducing UV exposure, and being thoughtful about the design of the project.

Is yellowing worse in clear epoxy?

Yes. Yellowing is usually more noticeable in clear or lightly tinted epoxy because there is less colour to hide the change.