Wet spots in your soy candle: causes and solutions

You’ve just poured the perfect batch of candles. The top is mirror-smooth, the smell is fantastic and you are proud of the result. But the next morning you look at the side of the glass and see strange stains. It looks like there’s water between the wax and the glass, or the wax is coming off in some places.

This phenomenon is called “wet spots” or adhesion problems. It is one of the most common frustrations for anyone working with soy wax. The good news? It doesn’t affect how your candle burns or smells at all. It’s purely cosmetic. Still, as a maker, you obviously want your candles to look as sleek as they smell. Below, we dive into the science behind these stains and look at how to prevent them.

What exactly are wet spots

Although the name suggests otherwise, these stains have nothing to do with water or moisture. What you see are spots where the wax has come loose from the glass. In the places where the wax is still firmly attached to the wall, the candle appears darker. Where the wax has come loose, there is a microscopic layer of air, making the glass look lighter or silvery.

Actually, this is just physics in action. Soy wax is a natural product that lives and works. It reacts constantly to temperature changes, even after the candle has been cured for a long time. This is in contrast to kerosene, which often remains more stable but has different properties.

The culprit is temperature

The root cause of wet spots is simple: shrinkage. When you melt candle wax, it expands. As it cools, it shrinks again. Glass is a solid material that does not visibly shrink or expand at these temperatures.

If the wax cools faster than the glass, or if the ambient temperature drops too quickly, the wax will shrink away from the walls of your glass containers. This often happens in random places, resulting in those typical stains. Factors such as cooling too quickly, pouring into ice-cold glasses or drafts in your workspace greatly exacerbate this process.

Here’s how to reduce the chance of staining

Avoiding them completely is quite a challenge with 100% soy wax, but you can drastically reduce the chances of these unsightly spots. It’s all about controlling the process.

Always start with spotless glasses. Dust, grease or fingerprints on the inside of your glass immediately cause poor adhesion. Wash your glasses with warm water and mild soap and dry them thoroughly. Even better, take a moment to wipe them down with a little alcohol before you begin.

Preheat your glassware. This is perhaps the most important step that many beginners skip. When you pour hot wax into a cold glass, the wax shakes. The outer layer solidifies directly against the cold glass while the core is still hot. This creates tension. Put your glasses in an oven on the lowest setting for a while or use a heat gun to warm them to about 40-50°C. The wax and glass will then cool simultaneously. Check out our guide on how to make a container candle for more basic steps in this process.

Pay sharp attention to your pouring temperature. Each wax has its own ideal point, but for soy wax, this is often lower than you think. If you pour too hot, the shrinkage during cooling is greater. Try pouring around 50-60°C, when the wax starts to get a little thicker and cloudier. A good thermometer is essential here, because guessing rarely works.

Control cooling. Do not place your freshly poured candles directly on a cold countertop made of stone or granite, as this draws heat from the bottom of the pot. Place them on a rack or wooden board. Make sure the candles are not in a draft and place them about 10 inches apart. That way they don’t transfer heat to each other, but they can cool off quietly. A stable room temperature of about 21°C works best.

Do you use a specific candle mold instead of glass? Then you’ll have less trouble with wet spots, but watch out for other defects such as trapped air. You can read more about that in our article on how air bubbles dissolve in candle wax.

Choose the right wax. Some waxes are more susceptible to wet spots than others. Pure soy wax is notorious, but blends designed specifically for containers often have additives that improve adhesion.

Repair existing law spots

Have you already poured and still see stains? Don’t panic. There’s a quick fix, even if it’s sometimes temporary. Use a heat gun (heat gun) to gently heat the outside of the glass at the spot of the stain. The wax on the inside will melt, liquefy and reflow against the glass. Then let the candle cool again very gently.

Keep in mind that soy wax continues to work. The stain may return over time as the temperature in the room changes.

A matter of acceptance

It is good to know that wet spots are a sign that you are working with natural wax. Many commercial candle manufacturers use kerosene or synthetic additives that prevent shrinkage, making the candle look perfect.

When you choose 100% soy-based candle wax, you are choosing a natural product with all its peculiarities. Many customers now know this and see it precisely as a proof of quality. Like candle frosting, it is a cosmetic feature that does not detract from the candle’s performance. Also, don’t forget to choose the right candle wick; a good burn is ultimately more important than a perfect side.

Try applying the tips above to optimize results, but don’t be too hard on yourself if a spot does appear. Keep experimenting with temperatures and, above all, enjoy the making process.