Frosting and Wet Spots in Candles: Causes and Fixes

Frosting and wet spots both look like flaws, but both are cosmetic. Frosting is a pale, crystal-looking layer on natural wax. Wet spots are glass-side patches where the wax shrank away from the jar. CandleScience says frosting is "solely an aesthetic issue and does not affect the way your candle burns or smells," and that wet spots do not change how a candle performs. You can reduce both, but you will probably never get rid of frosting completely in soy.

What is frosting?

CandleScience describes frosting as "a byproduct of a natural wax," caused by "the growth of tiny crystals on the surfaces of the wax." It shows up as a white, powdery or feathery coating on the top, or in streaks down the glass. It tends to be easier to see on dark wax or dark jars, because the contrast is stronger. I am saying that from my own bench experience, not from a source.

What are wet spots?

Wet spots are not wet. CandleScience says they are "places the wax has pulled away from the container as it cools." The wax shrinks as it sets, and when part of it cools faster than the rest, that part lets go of the glass. Light bends differently through the little gap, so the patch looks darker or glossy from outside. Makesy lists more causes: pouring too hot or too cold, pouring into cold jars, drafts or a cold room, and waxes that shrink more than others.

Do they change how the candle burns?

No, according to both suppliers. Makesy says the candle "will still burn beautifully," and that neither wet spots nor frosting affects how the candle burns or smells. A label can also hide a wet spot, as CandleScience points out. If your customers complain, the fix is a short note on your care card or product page, and testing a few of the changes below.

How do I reduce frosting and wet spots?

The two suppliers agree on most of this. Where they differ, I show both numbers. Check your own wax maker's sheet for pour temperatures, since they change by wax.

• Warm the jars. CandleScience says to preheat glassware but "not to heat your containers over 100°F." Makesy suggests a low oven at about 100 to 120°F (38 to 49°C) for a few minutes. Start at 100°F (38°C) and go no higher unless your supplier says so.
• Pour at the right temperature. Makesy says most soy waxes do best between 120 and 140°F (49 to 60°C). For frosting, CandleScience says a lower pour temperature can help, and to adjust it in 5°F (about 3°C) steps.
• Stir gently. CandleScience says over-agitating melted wax can speed up crystallization.
• Cool in a steady room. CandleScience says 70 to 76°F (21 to 24°C) is ideal, away from drafts. Makesy adds that "rushing the cooling process almost always makes things worse."
• Give the jars space. CandleScience says to set candles at least 4 inches (10 cm) apart while they cool, ideally on a wire rack instead of a solid surface.
• Pour slowly to limit trapped air and uneven cooling (CandleScience).
• Start with clean, dry jars. Wash and dry them, and handle them on the outside (Makesy).
• Try a different wax. Makesy names two of its own waxes for better glass adhesion. A new wax means a new round of wick tests.
• Fix a finished candle. Makesy suggests running a heat gun gently over the outside of the jar so the wax re-adheres.

Worked example: test one change at a time

The easiest way to find your fix is to change one thing per batch and count the results. These numbers are made up to show the method.

In this example, warming the jars cut the wet spots from 42 percent to 25 percent, and the lower pour temperature took it to 8 percent. Note the room temperature and the cooling spot for each test too, since a draft can ruin a comparison. If a change does nothing, drop it and try the next.

Common mistakes

• Treating frosting as a defect and discarding good candles.
• Changing three things in one batch, so you cannot tell what worked.
• Heating jars over 100°F (38°C) when your supplier says not to.
• Cooling candles in front of a fan or open window.
• Packing jars tightly on a tray right after pouring, so they cool unevenly.
• Promising customers "no frosting" on a natural wax.

Questions

Is frosting a sign of old or bad wax?

None of the sources I read say so. CandleScience says all soy wax will frost over time, and calls it a byproduct of natural wax. Frosting depends on how the wax cools and what it is made of, so a fresh batch can frost too.

Will a first burn get rid of frosting?

A burn melts the top layer, and the surface re-sets as it cools. I have not found a supplier source that promises it clears frosting for good, so I would not promise it to customers.

Should I tell customers about it?

Yes, briefly. A line such as "natural wax can show a white frost or glass-side patches; this does not change how the candle burns" saves you complaints. Keep it to what the sources support.