Nothing is more frustrating than finishing a beautiful resin project—only to see it slowly turn yellow over time. Whether it’s jewellery, coasters, wall art, or furniture, resin yellowing is a common issue faced by artists across India.
The good news?
Yellowing is not random. It happens for specific reasons—and most of them are preventable. This guide explains why resin turns yellow and exactly how to prevent it for long-lasting, crystal-clear results
What Is Resin Yellowing?
Resin yellowing is a chemical discoloration that occurs when epoxy resin reacts to:
- UV light
- Heat
- Oxygen
- Improper curing
- Low-quality raw materials
Over time, these factors cause the clear resin to develop a yellow or amber tint.
Top Reasons Why Resin Turns Yellow
1. UV Exposure (Sunlight)
- UV rays break down the chemical structure of epoxy resin.
- Happens faster in outdoor or sun-exposed areas
- Common in windows, balconies, wall décor near sunlight
Result: Gradual yellowing over weeks or months
2. Poor Resin Quality
- Low-grade or unrefined resins lack proper stabilizers.
- Cheaper resins yellow faster
- Inconsistent batches cause uneven discoloration
3. Excess Heat During Curing
- Overheating triggers oxidation.
- Thick pours without temperature control
- Using too much heat gun or torch
4. Incorrect Mixing Ratio
- Improper resin-hardener balance leads to incomplete curing.
- Unreacted chemicals remain inside
- These chemicals darken over time
5. Aging & Oxidation
- All epoxyresins naturally age.
- Even high-quality resin can yellow slightly over years
- Faster if exposed to heat, air, or light
6. Pigments & Additives
- Some pigments accelerate yellowing.
- Cheap dyes
- Non-resin-safe colorants
- Organic pigments without stabilizers
How to Prevent Resin Yellowing (Proven Methods)
1. Use UV-Resistant Resin
- Always choose resin with built-in UV stabilizers.
- Slows down yellowing dramatically
- Ideal for jewellery, coasters & décor
2. Control Temperature While Curing
- Ideal curing temperature: 24–28°C
- Avoid direct sunlight during curing
- Pour thick projects in layers
3. Mix Resin Properly
- Measure accurately
- Mix slowly for 3–5 minutes
- Scrape sides and bottom of mixing cup
- Proper curing = better long-term clarity
4. Avoid Overheating
- Use heat gun lightly
- Never hold flame in one spot
- Let bubbles rise naturally when possible
5.Add a UV-Protective Topcoat
- For items exposed to light:
- Apply a clear UV-protective resin topcoat
- Acts as a sacrificial layer against sunlight
6. Store Finished Resin Products Correctly
- Keep away from direct sunlight
- Avoid hot areas (cars, balconies)
- Store in cool, dry spaces
Common Myths About Resin Yellowing
❌ “Clear resin never yellows”
✔ False — all epoxy resins age
❌ “Yellowing means bad curing only”
✔ Not always — UV plays a major role
❌ “Heat gun prevents yellowing”
✔ Excess heat actually worsens it
Quick Checklist to Prevent Yellowing
- Use UV-resistant resin
- Mix accurately & slowly
- Cure at stable temperature
- Avoid sunlight during & after curing
- Use resin-safe pigments
- Apply UV topcoat for exposed items