Why Your Homemade Soy Candles Get Sinkholes and Wet Spots (And How to Fix Both)

You mixed your fragrance carefully, poured at the "right" temperature, and let the candle cure exactly as instructed — and yet there it is: a crater sinking into the top of your wax, or a cloudy patch clinging to the side of the jar like a bruise. Sinkholes and wet spots are two of the most common headaches in home soy candle making, and the good news is that neither one means you did something wrong. They mean soy wax is just doing what soy wax does when it isn't given the right conditions to cool.

What Sinkholes and Wet Spots Actually Are

A sinkhole is a dip or crater that forms in the surface of your candle, usually centered around the wick, as the wax cools and contracts. Soy wax shrinks noticeably as it solidifies — more than paraffin does — which is exactly why sinkholes are so common in 100% soy pours. A wet spot is different: it's a patch where the wax has pulled away from the glass on the inside of the jar, creating a translucent or foggy-looking gap you can see from the outside. Neither affects how the candle burns or smells. They're cosmetic. But if you're selling candles, or just proud of your work, cosmetic still matters.

The Real Cause: Wax That Cools Too Fast or Too Unevenly

Both problems trace back to the same root issue — temperature change. Soy wax is a natural product, and it's sensitive to its environment while it cures. When the outside of the candle cools faster than the inside (which happens constantly, since glass and metal jars conduct heat quickly), the wax contracts unevenly. The surface can crust over while the center is still liquid, and as that inner wax finally cools and shrinks, it pulls the surface down into a divot. Wet spots happen for a similar reason: as the wax contracts overall, it can separate slightly from the container wall, especially near room-temperature drafts, cold work surfaces, or a chilly garage.

If you've ever pulled a tray of candles out of a cold car trunk or set them by an open window to "cool faster," you've probably met both problems at once.

Your Pour Temperature Is Doing More Than You Think

Pour temperature is the single biggest lever you have. Pour too hot, and the wax has a long way to fall in temperature, which means more contraction and a higher chance of sinkholes. Pour too cool, and the wax may set before it fully bonds to the glass or fills in around the wick, leaving air pockets that show up as surface pitting later. Most soy wax blends want to be poured somewhere in the 120–135°F range, but always check your specific wax manufacturer's guidance — additive blends and wax from different suppliers can vary by 10–15 degrees. Consistency matters more than any single "magic number": pour every candle in a batch at the same temperature so your results are predictable.

The Fix Most Makers Skip: A Second, Smaller Pour

The single most effective fix for sinkholes is a technique called the second pour, or "repour." Instead of trying to get one perfect pour, you deliberately plan for two:

Pour your candle as normal and let it cool undisturbed at room temperature — no fridge, no drafts, no fans. Once it's fully set (usually a few hours, sometimes overnight), you'll likely see a small sinkhole form around the wick. At that point, reheat a small amount of the same wax and fragrance blend to your pour temperature and do a thin second pour, just enough to fill the divot level with the rest of the surface. Let it cure fully before trimming the wick. This is exactly the technique we rely on for glassy-smooth tops on batches like Egyptian Amber and Cracklin Birch — dark, dense wax blends that are especially prone to sinkholes if they're only poured once.

For wet spots, controlling the cooling environment does the most work: cure candles at a steady room temperature, ideally 65–75°F, away from windows, vents, and cold floors. Some makers also warm their containers slightly before pouring (a quick pass with a heat gun or a few minutes in a low oven) so the wax and the glass aren't fighting a big temperature gap from the very first second.

When It's the Wax, Not You

If you're doing everything right and still seeing sinkholes or wet spots on every single pour, it might be worth looking at your fragrance load or your wax-to-additive ratio. Overloading fragrance oil beyond what your wax can hold can destabilize how it sets. It's also worth testing a different soy blend — some are simply more prone to shrinkage than others, and a wax that's more forgiving might save you a lot of second-guessing, especially if you're troubleshooting scent throw at the same time as appearance. A candle like Hiking Trail, with its lighter, greener fragrance profile, tends to behave more predictably than heavier, resin-forward blends — a good reminder that appearance and fragrance chemistry are more connected than they first seem.

Quick takeaways

• Sinkholes and wet spots are cosmetic, not safety issues — your candle still burns and smells exactly as intended.
• Both come from uneven cooling: control your pour temperature and cure candles at a steady room temperature, away from drafts.
• A thin second pour, done after the first layer sets, is the most reliable fix for sinkholes around the wick.
• Warming your containers slightly before pouring helps prevent wet spots along the glass.
• If it happens on every batch, look at your fragrance load or try a different soy wax blend before blaming your technique.

Every candle maker — including us — has pulled a candle out of the mold and sighed at a crater or a cloudy patch. It's part of learning how soy wax behaves. At Sweet U Candles, we treat every "flawed" batch as data: adjust the pour, adjust the cure, and try again until the top is glassy and the sides are clear. That's the whole craft.