Guide
Wet spots on candles: what causes them and how to prevent them
Wet spots are patches on the side of a glass candle jar that look damp or darker than the rest of the wax. They aren't wet. They are places where the wax pulled away from the glass as it cooled and shrank, leaving a thin air gap. CandleScience says they don't affect how a candle burns or smells. To prevent them, start with clean, dry jars warmed to about 100 to 110°F, pour slowly, tap out air bubbles, and let candles cool slowly at around 70 to 72°F on a wire rack, spaced about 4 inches apart and away from drafts.
Why wet spots happen
All wax shrinks as it cools from liquid to solid. If one part of the jar cools faster than another, the wax there contracts and lets go of the glass while the rest stays stuck. The result is a patchy pattern that shows through clear glass.
- Cold jars. Hot wax poured into cold glass cools unevenly where it touches the jar.
- Uneven cooling. Drafts, fans, air vents, a cold room, or candles packed closely together make some sides cool faster than others.
- Cold surfaces. Stone or metal counters pull heat out of the jar's base.
- Pour temperature. Makesy notes that wax poured too hot shrinks more as it cools, while wax poured too cool may not bond to the glass.
- Trapped air. Fast stirring or pouring can leave air bubbles against the glass.
- Dirty or uneven glass. Dust, oils from fingers, or glass with thick and thin areas cool and grip the wax unevenly.
Both soy and paraffin candles can get wet spots. Sources disagree on which is worse, but every wax shrinks, so the fixes are the same.
Wet spots, frosting or something else?
| What you see | What it is | Affects the burn? |
|---|---|---|
| Darker, damp-looking patches on the sides | Wet spots: wax separated from the glass | No |
| White crystals or chalky film | Frosting: soy wax crystallizing | No |
| Oily droplets on top | Sweating: excess fragrance oil or heat | Can, if there's too much oil |
| Dip or hole near the wick | Sinkhole: wax shrinking in the middle | Can, if there's an air pocket under it |
How to prevent wet spots
- Clean and dry the jars. CandleScience suggests washing glass in mild soapy water and drying it completely. Hold jars by the outside so you don't leave oils on the inner wall.
- Warm the jars. Preheat them in a low oven to about 100 to 110°F (38 to 43°C) just before pouring, so the glass is closer to the wax temperature.
- Pour at your wax's recommended temperature. Use a thermometer and keep the temperature consistent from batch to batch. If you still get wet spots, test a few degrees warmer or cooler.
- Pour slowly and tap. Pour gently, then tap the jar a few times to release trapped air.
- Cool slowly and evenly. Let candles set in a room around 70 to 72°F (21 to 22°C), away from fans, vents and windows.
- Give them space and the right surface. Space candles about 4 inches (10 cm) apart on a wire rack, or on wood or cardboard, rather than stone or metal.
- Choose even glass. Jars with uniform wall thickness cool more evenly than jars with thick and thin areas.
How to fix wet spots
Makesy suggests running a heat gun gently over the outside of the jar. Warming the glass softens the wax so it can stick again. Keep the heat moving and stop once the patch disappears, so you don't melt the candle unevenly. Wet spots can come back if the candle goes through big temperature swings, for example in shipping.
If you sell candles, two simple ways to hide the spots are:
- Frosted, tinted or opaque jars, where wet spots barely show.
- Labels placed over the area where wet spots usually form.
Some sellers mention on the product page that wet spots are a normal cosmetic feature of handmade candles, which reduces returns.
Do wet spots affect the candle?
No. CandleScience says wet spots don't affect how the candle burns, and Makesy and Supplies For Candles say they don't affect scent throw either. A candle with wet spots is as safe to burn as one without them. It's a cosmetic issue, though a noticeable one in clear glass.
Frequently asked questions
What are wet spots on candles?
Wet spots are patches on a glass candle jar that look damp. They're places where the wax pulled away from the glass as it cooled and shrank, leaving a thin air gap. They aren't liquid and don't affect how the candle burns.
Are wet spots bad?
No. They are cosmetic only. CandleScience says they don't affect how the candle burns, and other suppliers say they don't change the scent throw.
How do I prevent wet spots in soy candles?
Use clean, dry jars warmed to about 100 to 110°F, pour slowly at your wax's recommended temperature, tap out bubbles, and cool candles slowly at around 70 to 72°F on a wire rack, about 4 inches apart and away from drafts.
Can you fix wet spots with a heat gun?
Often, yes. Gently warming the outside of the jar with a heat gun can soften the wax so it sticks to the glass again. Keep the heat moving. The spots can return if the candle is exposed to big temperature changes.
What's the difference between wet spots and frosting?
Wet spots look darker or damp, where wax has separated from the glass. Frosting looks white and chalky, from soy wax forming crystals. Both are cosmetic and neither affects the burn.
White crystals as well? That's frosting, which has different causes. See candle frosting: why soy candles turn white.