"Waited 72 hours like the instructions said. The top feels hard but the inside is still soft and I can dent it with my fingernail. Did I get a bad batch or did I do something wrong?" — Reddit r/resin, one of the most common deep pour troubleshooting posts
Almost always, it's something that happened before or during the pour — not the product itself. Deep pour epoxy failures are frustrating precisely because they seem random when they're actually very predictable. The same five causes come up again and again, and most of them are completely preventable once you know what to look for.
Sticky surface or soft interior in deep pour epoxy traces back to five causes: incorrect mixing ratio, insufficient mixing, ambient temperature too low, pour depth too thick for the project size, or moisture contamination. Every single one is preventable — but only fixable before it happens, not after.
Find your symptom in the table below, jump to the cause, and work through the fix. If the piece is already cured wrong, the last section tells you honestly whether it can be saved or needs to be started over.
Find Your Problem First
| What you're seeing | Most likely cause | Jump to |
|---|---|---|
| Surface feels slightly tacky but piece seems otherwise solid | Minor mixing ratio deviation or normal oxygen inhibition layer | Cause 1 → |
| Soft spots in specific areas, rest of piece is fine | Insufficient mixing — unmixed material from container edges | Cause 2 → |
| Entire piece soft or rubbery after full cure time | Temperature too low, or significant mixing ratio deviation | Cause 3 → |
| Interior permanently liquid despite hard surface | Pour too thick or excess heat trapped inside the pour | Cause 4 → |
| White haze, waxy film, or cloudiness on surface | Moisture contamination or amine blush | Cause 5 → |
Deep pour epoxy is a two-component chemical system. Part A (resin) and Part B (hardener) react together in a precisely calibrated ratio to produce the cross-linked polymer network that makes cured epoxy hard and stable. Get that ratio wrong — even by a few percent — and the chemical reaction doesn't complete properly.
- Always measure by volume, not weight — unless the product specifically states weight ratio (most don't)
- Use calibrated measuring cups with clear markings, not cups with approximate scales
- Measure Part A and Part B in separate containers before combining — never estimate visually in the mixing container
- For large pours, use a digital scale as a cross-check if your product provides a weight ratio
- Bond Craftor Deep Pour Epoxy uses a 2A:1B volume ratio — measure both components separately before mixing
Even with a perfect ratio, incomplete mixing produces a failed pour. The problem is usually invisible: unmixed or poorly-mixed resin hiding along the sides and bottom of the mixing container. These "dead zone" pockets of pure Part A or pure Part B get poured into the mold and create soft spots that no amount of curing time will fix.
- Mix for a minimum of 3–5 minutes, actively scraping the sides and bottom of the container throughout
- Use the double-container method: after mixing thoroughly in the first container, pour into a second clean container and mix for another 1–2 minutes — this eliminates unmixed material stuck to the original container walls
- Mix slowly and steadily — aggressive fast stirring introduces air bubbles without improving mixing quality
- The mix is ready when it looks completely clear and uniform with no streaks, swirls, or cloudiness
Epoxy curing is a chemical reaction, and like all chemical reactions, it's sensitive to temperature. Colder conditions don't just slow the cure down — below a certain threshold, they effectively halt it. Many people pour in a cold garage in winter, check back after the stated cure time, and find a soft, rubbery piece that isn't close to fully hardened.
- Maintain ambient temperature between 18–29°C (64–84°F) throughout the entire cure period — not just during the pour
- If working in a cold garage or basement, use a space heater to bring the space to temperature before pouring and keep it warm during cure
- A heating blanket placed around (not directly under) the mold can help maintain temperature in a cold environment
- If your piece is already soft due to cold, move it to a warmer environment (25–30°C) and give it an additional 24–48 hours — cold-related soft cures can sometimes recover with added heat and time
- Warm both components to room temperature before mixing — cold resin is also more viscous, making bubbles harder to remove
This is the failure mode that catches experienced makers off guard, because it doesn't follow intuition. You poured exactly the same depth that worked on a small test piece. The surface cured beautifully. But the interior is still soft, or worse, the piece cracked and yellowed from overheating.
Maximum safe single-layer pour depth depends on your product formula, the ambient temperature, and the surface area of your project. The product's stated maximum depth applies to standard conditions — for large river tables or wide slabs, you need to reduce that depth further and pour in multiple layers.
- For projects over approximately 6 sq ft, reduce single-layer pour depth below the product maximum and build up in multiple layers
- In warm weather (above 25°C), reduce pour depth further — heat accelerates the exothermic reaction
- Wait for each layer to reach firm initial cure before adding the next — pouring onto a still-warm previous layer adds heat to an already exothermic situation
- Never let mixed epoxy sit in the bucket — pour immediately after mixing. Resin in a concentrated mass heats faster than resin spread across a mold
This one is sneaky because you can't see it happening. Moisture contamination — whether from humid air, damp wood, water droplets in the mixing container, or improperly stored materials — interferes with the curing chemistry and produces a characteristic set of symptoms that look different from the other four causes.
- Keep ambient humidity below 85% RH during both application and the full cure period
- Never work in rain or high-humidity conditions — even indoor humidity above 85% is enough to cause blush
- For wood projects, verify moisture content is below 12% before pouring — use a moisture meter, not visual inspection
- Make sure mixing containers and tools are completely dry before use — even small water droplets can cause localized contamination
- Store Part B (hardener) sealed tightly — amine hardeners are hygroscopic and absorb moisture from the air if left open between uses
- For surface blush (waxy film): wipe with warm water and a stiff brush — blush on the surface can sometimes be removed this way without affecting the cure underneath
Can It Be Saved? What to Do When It Happens
The honest answer depends on how bad the problem is and what caused it. Here's the real breakdown.
- Continue curing at room temperature for another 24–48 hours
- Move to a warmer environment (25–30°C) to accelerate the remaining cure
- Wipe surface with isopropyl alcohol — if tackiness disappears, it was oxygen inhibition (normal), not a cure failure
- Monitor: if it continues to harden over 24 hours, you may be fine
- A fundamentally incorrectly cured piece cannot be fixed by adding more epoxy on top
- The soft layer will remain soft and will cause any new pour over it to fail as well
- The piece needs to be discarded and remade
- Before remaking: identify which of the 5 causes applied and correct it first
Before Your Next Pour — Prevention Checklist
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1Confirm mixing ratio. Re-read the product label before every pour — don't rely on memory. Bond Craftor Deep Pour Epoxy is 2A:1B by volume.
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2Measure in separate containers. Measure Part A and Part B individually before combining. Never estimate in the mixing container.
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3Mix for 3–5 minutes using the double-container method. Scrape sides and bottom. Transfer to a second container and mix again.
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4Check ambient temperature. Must be 18–29°C throughout the pour and cure period. Measure at mold level — not just room air temperature.
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5Calculate pour depth for your project size. Large projects need shallower layers than the product maximum. When in doubt, go thinner and add a second layer.
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6Check wood moisture. If pouring over wood, confirm moisture content is below 12% with a moisture meter.
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7Check ambient humidity. Keep below 85% RH during both application and the full cure period. Never pour during rain or high-humidity days.
Questions People Ask About Deep Pour Epoxy Curing Problems
How deep can you pour deep pour epoxy in a single layer?
It depends on the specific product formula, the ambient temperature, and the surface area of your project. Bond Craftor Deep Pour Epoxy can reach up to 4 inches (10cm) per layer at 18°C on standard-sized projects. At warmer temperatures (25–32°C), reduce to approximately 2 inches (5cm). For large-surface-area projects like full dining tables, reduce single-layer depth further regardless of temperature, because larger resin volume generates more accumulated heat. When in doubt, pour thinner and add a second layer after initial cure.
Can I use deep pour epoxy for wood projects like river tables?
Yes — deep pour epoxy is specifically designed for river tables and large wood castings. The key wood-specific preparation steps are: verify wood moisture content is below 12% before pouring (use a moisture meter), apply a thin seal coat of epoxy to the wood surface first to prevent air bubbles from rising out of the wood grain, and allow the slab to acclimate indoors for at least two weeks before pouring so it stops moving.
Can I add pigment or color to deep pour epoxy?
Yes, but with limits. Keep total colorant — pigment paste, mica powder, alcohol ink — below 3–5% of total resin volume. Exceeding this threshold doesn't just change the color; it can physically interfere with the curing process by absorbing heat differently or blocking the curing reaction at higher concentrations. Dark, opaque pigments are particularly prone to causing problems at high concentrations. For deep pours where you want a colored base layer, Bond Craftor Black Epoxy Resin is a pre-tinted option that eliminates the mixing guesswork.
The surface wiped clean with alcohol but the interior is still soft — is that fixable?
If the surface tack wiped away with isopropyl alcohol, that was normal oxygen inhibition — a thin incompletely-cured layer at the very top surface that all epoxy produces. That's not a cure failure. However, if the interior of the piece remains soft or rubbery after the full cure period, that's a genuine cure problem (ratio, temperature, or pour depth) and the piece cannot be saved by adding more epoxy on top. The interior will remain soft permanently.
How long should deep pour epoxy actually take to fully cure?
Bond Craftor Deep Pour Epoxy reaches initial cure (firm enough to demold) at approximately 72 hours at 18–25°C. Full cure — where the interior has hardened completely and the piece can be sanded, machined, or used — takes 72–168 hours (3–7 days) depending on pour depth, temperature, and the specific formula. Thicker pours and cooler temperatures push toward the longer end of that range. Don't sand, machine, or apply a topcoat until the piece has passed the full cure window.