Understanding the causes of epoxy resin yellowing

Epoxy resin is highly valued in the fields of decoration, crafts, and DIY, particularly for its crystal-clear transparency and ultra-glossy finish. However, a recurring issue faced by many users is the yellowing of epoxy resin over time. This unsightly change can reduce both the visual appeal and the longevity of your projects.

Yellowing is generally caused by:

  • Exposure to UV rays

  • Temperature fluctuations

  • The quality of the raw materials used

When resin is exposed to sunlight, UV rays alter its chemical structure, leading to gradual yellowing. High temperatures can also accelerate this process.

Techniques to prevent yellowing

Choosing a high-quality resin

To reduce the risk of yellowing, opt for a high-quality resin, ideally formulated with UV inhibitors. These additives act like sunscreen for the resin, slowing down colour degradation.

Using a UV-resistant protective varnish

Applying a protective varnish, such as a transparent polyurethane-based varnish, creates a physical barrier against UV rays. For optimal protection, it is recommended to apply several coats.

Choosing the right hardener

An incorrect choice of hardener can accelerate yellowing. Select hardeners formulated with UV stabilisers and strictly follow the recommended mixing ratios to ensure proper curing.

Other best practices

  • Limit UV exposure: place resin objects away from windows or under shelter for outdoor projects.

  • Control temperature: maintain a stable ambient temperature between 20°C and 25°C during curing.

  • Adopt proper pouring techniques: favour thin layers to reduce heat build-up during the curing reaction.

  • Add anti-oxidant additives: incorporate HALS stabilisers to extend the clarity and durability of the resin.

Maintenance and storage of epoxy resin

To preserve your resin creations:

  • Clean them using mild, non-abrasive products.

  • Prevent scratches by using protective items such as trivets or cutting mats.

  • Store resin in airtight containers, away from light, and at a stable temperature between 15°C and 25°C.

Take action

Looking for the best epoxy resin for your projects? Discover our selection of products specially formulated to resist yellowing at Boutique Résine Epoxy. Turn your ideas into durable, brilliant creations.