Does heat make resin yellow more quickly?

Why does heat cause resin to yellow?

Exposure to high temperatures speeds up the natural ageing process of epoxy resin. This leads to chemical changes within the resin, often resulting in an unwanted yellowish tone. Whether the resin is freshly cured or has been in place for a while, leaving items in a hot environment—such as near radiators, in direct sunlight, or inside a car on a warm day—can hasten visible yellowing. As such, minimising heat exposure is recommended for resin pieces you wish to keep clear for longer.

Tips for preventing heat-related yellowing

• Choose formulations with UV and heat resistance: Some epoxies, like “Trasparente” clear casting resin and “Icrystal”, contain filters designed to resist yellowing caused by heat and sunlight.
• Store away from heat sources: Keep cured resin out of direct sun or hot places. For smaller items, storage in a cool, shaded area is best.
• Follow recommended thickness: Pouring layers thicker than suggested can lead to excessive heat during curing, which may also increase yellowing risks.

When this matters

If your project will be used outside, in kitchens, or other warm areas, heat resistance and anti-yellowing features become especially valuable. This is particularly true for decorative and functional items intended to look clear and bright for years to come.