How to Use Epoxy Resin in Silicone Molds (No Bubbles, No Sticky Cures)
If you’ve ever pulled a piece from a mold and thought, “Why is it still bendy… and why does it have a million bubbles?”—you’re not alone. Epoxy resin is forgiving in creativity, but it’s unforgiving in measurement and mixing.
The good news: once you learn a few non-negotiables (accurate ratios, slow mixing, controlled pouring, proper cure temperature), resin becomes a repeatable craft you can trust—whether you’re making a glossy tray, a jewelry dish, or a sculptural décor piece.
If you’re planning to cast décor pieces, start with mold shapes that release cleanly and show off shine—explore Fynzio’s silicone mold collections here: https://fynzio.com/collections/resin-molds
What Epoxy Resin Is (and Why Silicone Molds Are the Sweet Spot)
Epoxy resin is a two-part system:
- Part A: Resin
- Part B: Hardener
When mixed at the correct ratio, they crosslink into a solid plastic-like material with that signature glassy finish.
Why silicone molds work so well: silicone is flexible and non-stick, so cured resin releases with minimal sanding and fewer surface defects—especially compared to rigid molds.
Safety First (Non-Negotiable, Even for Small Pours)
Epoxy is a craft material, but it’s still chemistry.
Many Safety Data Sheets include hazard statements like skin sensitization and irritation (e.g., “may cause an allergic skin reaction”), and recommend protective measures like gloves, eye protection, and avoiding inhalation of vapors/mist. And occupational health literature notes allergic contact dermatitis is a common issue with epoxy exposures in workplaces.
My baseline safety setup (small studio / home crafting)
- Nitrile gloves (latex can degrade with some chemicals)
- Eye protection (splashes happen during mixing)
- Ventilation: open windows + fan moving air out
- Cover skin: long sleeves if you’re messy like me
- No food/drinks on the resin table
Hands-on note (tested workflow): In our internal craft testing, the biggest “oops” moments happen during pigment stirring and cup scraping—exactly when hands drift toward faces. Gloves + a dedicated wipe station prevent most of that chaos.
Tools & Materials Checklist (So You Don’t Pause Mid-Pour)
Before you mix anything, set up like you’re about to cook a recipe you can’t restart.
Essentials
- Epoxy resin + hardener (compatible set)
- Silicone mold(s)
- Graduated mixing cups (or a scale if mixing by weight)
- Stir sticks (flat sticks scrape better than round)
- Nitrile gloves + paper towels
- Isopropyl alcohol wipes (cleanup)
- Bubble control tool: heat gun (gentle) or torch (careful)
Nice-to-have (seriously helpful)
- Silicone mat for your workspace
- Level (or a leveling app)
- Dust cover (storage bin or box)
Mid CTA: Planning a tray, dish, or décor pour? Browse shapes that demold cleanly and photograph beautifully: https://fynzio.com/collections/resin-molds
Step-by-Step: How to Use Epoxy Resin in Silicone Molds (The No-Sticky Workflow)
Step 1) Prep your mold (clean + dry = glossy)
- Wash new molds with mild soap, rinse, and let fully dry.
- Remove dust with tape or a lint-free cloth.
- Place mold on a level surface.
Pro tip: Dust is the sneakiest cause of “mystery bumps.” I like to set molds under a plastic bin for 10 minutes before pouring so airborne fibers settle elsewhere.
Step 2) Measure accurately (this is where cures succeed or fail)
Your resin system will specify a ratio—often 1:1 or 2:1 (resin:hardener). Mix ratios may be by volume or weight, and you must follow the brand’s rule.
If your resin is 1:1 by volume:
- Pour Part A to your desired line, then Part B to match.
If using a scale (by weight):
- Tare the cup, add Part A, then add the exact Part B weight per instructions.
Common measuring mistakes
- Eyeballing (it’s almost never exact)
- Using a cup with unreadable markings
- Confusing “by weight” ratios with “by volume” (can cause cure failure)
Helpful tool: If you’re calculating pour volume for a mold, use a resin calculator to avoid waste. Fynzio has a handy one here: https://fynzio.com/pages/resin-calculator
Step 3) Mix slowly, scrape thoroughly, and mix longer than you think
Pour Part B into Part A, then stir slowly—think “folding batter,” not whisking eggs.
My tested mixing method (works ridiculously well):
- Mix 2 minutes slowly, scraping sides and bottom
- Let sit 1 minute (bubbles rise)
- Mix 1–2 more minutes, scraping again
- Optional: transfer to a second clean cup (“double cup method”) and mix 30 seconds
This reduces streaks (unmixed resin) that cause tacky spots.
Step 4) Add color (without whipping in bubbles)
Add mica, dye, or alcohol ink after initial mixing.
- Stir pigments gently
- Avoid overloading (too much pigment can affect cure)
- For layered looks, split into smaller cups for control
Step 5) Pour like a pro: thin stream, edge-first
For silicone molds, the goal is to avoid trapping air in corners and details.
Best practice pouring:
- Pour in a thin stream from 6–12 inches above the mold (helps pop bubbles on the way down)
- Start at the lowest point / deepest corner
- Let resin “push” into the shape instead of flooding it
If your mold has fine details: Use a stir stick to “paint” a thin layer into details first, then fill.
Step 6) Bubble removal (gentle heat, short bursts)
Once poured, wait 2–3 minutes. Then:
- Pass a heat gun briefly across the surface (keep moving)
- Or use a torch very lightly (farther away than you think)
Don’t overheat. Too much heat can warp silicone, ripple surfaces, or accelerate cure unevenly.
Step 7) Cover and cure (temperature matters more than beginners realize)
Cover the mold to prevent dust landing on your glossy surface.
Then let it cure at your resin’s recommended temperature. Cold rooms slow curing and can contribute to soft or tacky finishes.
Real-world note: If your space drops cold overnight, consider curing in a warmer interior room. Stable temperature = consistent results.
Step 8) Demold at the right time (patience protects edges)
Demold only when fully hardened—not just “surface hard.”
To release:
- Peel mold edges back gently
- Push from the base, don’t yank the piece by thin features
- If it resists, wait longer (forcing causes chips and stress marks)
Troubleshooting: Fix the 7 Most Common Resin Problems
1) Sticky or soft resin (even after “full cure time”)
Likely causes:
- Incorrect ratio (most common)
- Under-mixing (streaks of unmixed resin/hardener)
- Too cold during cure
Fix: If it’s tacky from bad mixing, you usually can’t “save” it fully. Scrape off what you can, clean the mold, and repour correctly.
2) Tons of bubbles
Likely causes:
- Fast mixing
- Pouring too thick, too fast
- Cold resin (higher viscosity traps air)
Fix: Warm sealed bottles in lukewarm water, mix slower, and pour in a thin stream. Use gentle heat after pouring.
3) Cloudy or dull finish
Likely causes:
- Moisture in mold or on additives
- Dust settling during cure
- Overheating surface with torch/heat gun
Fix: Dry everything, cover cures, and use shorter heat passes.
4) “Fish eyes” or craters
Likely causes:
- Oil/contaminants (silicone spray residue, hand lotion, etc.)
Fix: Wash mold with mild soap and dry fully. Keep skincare products away from your work area.
5) Resin pulls away from edges
Likely causes:
- Mold contamination
- Temperature swings during gel phase
Fix: Clean mold, stabilize cure temperature, and avoid moving the piece while it gels.
6) Warping or ripples
Likely causes:
- Too much heat while popping bubbles
- Pour too thick for the resin system (exotherm)
Fix: Use thinner pours or a resin designed for deeper pours, and apply heat minimally.
7) Resin sticks to the mold (hard demold)
Likely causes:
- Not fully cured
- Worn mold surface (after many uses)
- Cure inhibition from contaminants
Fix: Wait longer; wash and dry the mold; replace heavily worn molds for perfect releases.
Mini Project Ideas That Look Amazing in Silicone Molds
If you want quick wins that build confidence:
- Coasters (easy to level, satisfying demold)
- Trinket trays (great pigment practice)
- Sculptural candle holders (resin décor, not flame exposure)
- Keychain blanks and letter casts
If you love modern home décor casts, explore Fynzio’s bestseller collections for shapes that show off a glassy finish: https://fynzio.com/collections/best-sellers
Why Safety & Consistency Matter
Epoxy systems commonly carry warnings about skin sensitization (allergic reaction risk) across many SDS documents. Occupational health reports also highlight epoxy resins as notable causes of allergic contact dermatitis, and studies of exposed workers show meaningful dermatitis prevalence among those sensitized. Even beyond workplaces, EPA documents have historically discussed large-scale exposure potential through consumer and commercial epoxy uses.
This isn’t meant to scare you—it’s meant to help you craft smart: gloves on, air moving, and good habits from day one.
About the Author (Fynzio)
Written by the Fynzio content team—makers obsessed with crisp details, glossy finishes, and molds that release cleanly. Our tutorials are built from practical bench testing: measuring methods, mixing times, bubble control, and demolding techniques you can repeat confidently.
Need help choosing a mold for your next pour? Contact us: https://fynzio.com/pages/contact
Last updated: December 25, 2025
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