Why Is My Resin Cloudy? Discover the Main 6 Causes

Understand what’s dulling your shine—and how to fix it.

You’ve poured your heart (and hardener) into a resin project… only to wake up to a cloudy, hazy finish instead of the glass-like clarity you expected. Sound familiar?

Don’t worry—cloudy resin is a common issue, and the good news is: it’s usually fixable (or preventable next time). In this post, we’ll walk through the 6 main reasons your resin may turn cloudy, along with easy tips to get that crystal-clear finish every time.

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☁️ 1. Improper Mixing

What’s happening:

When resin and hardener aren’t mixed thoroughly or at the correct ratio, the chemical reaction doesn’t fully complete. The result? A cloudy, sticky, or soft surface.

How to fix it:

• Mix exactly as directed—usually a 1:1 or 2:1 ratio (check your brand instructions).
• Stir slowly but thoroughly for at least 3–5 minutes, scraping the sides and bottom of your container.
• Use clear mixing cups with measurement lines for accuracy.

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❄️ 2. Cold Temperatures

What’s happening:

Resin reacts poorly in cold environments. If your room or materials are below the recommended temperature (usually 70–75°F / 21–24°C), the resin thickens and traps microbubbles, making the finish look milky or foggy.

How to fix it:

• Warm your resin bottles in a warm water bath (sealed and upright) before mixing.
• Ensure your workspace is warm and draft-free (use a space heater if needed).
• Avoid working in cold garages, basements, or near windows in winter.

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💨 3. Excess Bubbles

What’s happening:

Too many air bubbles in your mix or pour can rise to the surface and get trapped, giving your resin a cloudy look—especially in deep molds or layers.

How to fix it:

• Stir slowly to minimize bubble creation.
• Pour in layers and let each layer sit for 1–2 minutes before popping bubbles.
• Use a heat gun or torch (briefly!) to pop surface bubbles right after pouring.

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💧 4. Moisture Contamination

What’s happening:

Water + resin = trouble. Even a small amount of moisture from a mold, tool, or air humidity can cause clouding, bubbling, or even foaming.

How to fix it:

• Make sure your molds and tools are completely dry before starting.
• Avoid mixing resin on rainy or super humid days.
• Store your resin in a cool, dry place, sealed tightly.

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🕓 5. Expired or Old Resin

What’s happening:

Over time, resin can degrade—especially if stored improperly or exposed to temperature swings. Old resin may turn yellow, separate, or create a cloudy finish when cured.

How to fix it:

• Check the expiration date and shelf life (usually 6–12 months after opening).
• Always store in a cool, dark place, away from direct sunlight.
• If resin has separated or smells “off,” it’s safer to toss it.

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🧼 6. Residue in Molds or Cups

What’s happening:

Leftover cleaning agents, soap, dust, or oils can cause a chemical reaction or stop the resin from curing properly—leading to haziness.

How to fix it:

• Clean molds with isopropyl alcohol and let them fully dry before pouring.
• Avoid soapy water unless you rinse and dry meticulously.
• Always handle molds with clean hands or gloves.

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✨ Bonus Tips for Crystal-Clear Resin:

• Use quality resin specifically made for art or casting—not industrial brands.
• Work in a dust-free area to avoid particles settling mid-cure.
• Use a UV-resistant resin for projects that will be in sunlight.

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💬 Final Thoughts

A cloudy resin project can be disappointing, but it’s also a fantastic learning moment. With a few adjustments to your materials, workspace, and technique, you’ll be on your way to flawless, glass-like finishes in no time.