By Bob Sherman
This article was originally written in 1997 and has been rewritten, modernized, and modified for this web site.
Mottled candles have long been a problem for many and sought after by a few. Most candle makers that use oil based scents have at one time or another accidentally made mottled candles. In this article I will discuss both how to avoid mottling as well as how to get your candles to mottle.
PLEASE NOTE! - Candle making can be dangerous if proper safety procedures are not followed. Please read these Safety Rules before attempting any candle making projects.
What Is Mottling?
Mottled wax for our purposes is wax that exhibits a random "snowflake" pattern on the finished candle. While air bubbles and other defects in molded and container candles may give a mottled appearance, that is not the effect we are discussing. This mottled snowflake appearance is caused by a chemical reaction with oils in the wax when certain combinations of temperature and cooling time occur, which is why many of us encounter it during the course of normal candle making.
What Causes Mottling?
As mentioned previously, the main ingredient in mottling is oil. There are two common sources of oil in candles. Paraffin wax is an oil based product so it contains some oil and some waxes have a higher oil content than others. Another common source of oil in candles are oil based scents. Waxes with a high oil content may mottle without the addition of any oil under certain conditions.
The only way I know to guarantee your candles will not mottle under any conditions is to use Vybar 103 (for harder waxes) or Vybar 260 (softer waxes). These Vybars completely inhibit the mottling reaction and I have never seen a candle containing them mottle.
If you desire to produce mottled candles you must first understand that two things need to happen - the wax must contain sufficient oil and the candle must cool within a certain speed range. For the sake of simplicity I will refer to these as oil content and cooling speed from here on.
Although it varies from one wax to the next, I find that adding one ounce of oil to most waxes will cause mottling. Depending on your scent oil that alone may be enough. This works better with "oily" scents than it does with less oily scents such as citrus scents. For unscented candles or candles with less oily scents, the addition of mottling oil may be necessary. Bear in mind that the paraffin wax you are using may have high or low oil content so you may need to add more or less oil.
This is the tricky part so be prepared to do lots of experimentation. To mottle, candles need to cool slowly, but not too slowly. Cooling too fast or too slow will prevent mottling. Mottling occurs best when cooled within a fairly narrow range of cooling speeds. Unfortunately there is no easy way to describe or measure this cooling speed so some trial and error will be required.
There are several factors that affect cooling speed such as pouring temperature and room temperature, but the most important is mold size. The larger a mold is, the longer it takes to cool. Large molds are much easier to make mottled candles in than small molds. Small molds such as votives which can air cool within 2 hours are extremely difficult to mottle candles in. A large mold such as a 6 x 6 inch pillar which takes approximately 24 hours to air cool will mottle with pretty much no effort. This is further complicated by fluctuations in room temperature although pouring temperature is easily controlled.
Most often you will be looking for methods to slow the cooling speed. Some popular techniques for slowing cooling time:
- Placing a box atop the mold after pouring (not touching).
- Placing the molds in a cooler or other insulated container.
- In difficult cases some folks use an oven although I don't recommend it. Extreme care must be used. The molds are placed on baking sheets and positioned in an oven preheated to 150 degrees F. until cool. Use caution that no wax gets spilled in the oven as this would be an extreme fire hazard when the oven is later used.
Carrier oil is my oil of choice for mottling wax. It is basically unscented scent oil and I always keep some in my workshop. Most importantly, it does not have any adverse effects when burning the candle. There are other oils marketed as "mottling oil" but I have had better results with carrier oil. I have also seen solid mottling additives which I have not been impressed with. Mineral oil works well too and is inexpensive and commonly available in your local supermarket.
The exact amount of oil needed will vary with the brand and melting point of your wax. I have found that most waxes will mottle with wax formulas in the range of 3 to 9 percent oil. As a general guideline, low melt point waxes typically have a higher oil content and require less oil to achieve mottling but there are some exceptions. I prefer to mottle with no hardeners or other additives in the wax although some folks add a bit of stearic. If you are using scent oil, less mottling oil will usually be needed.
Basic candle making techniques are used with the following exceptions. Pour at a higher than normal temperature. Cool as slowly as possible. The mottling occurs while cooling, and slowing the cooling process improves the mottling up to a certain point. Mottled candles have visual interest, but usually take a bit of experimentation to get optimum results with your wax, molds, and shop conditions.
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Disclaimer: The information presented here is accurate to the best of my knowledge and common candle making practices as of the time of this writing Originally published in November 1997 and has been updated and modernized in August 2007 and July 2011. The author and the publisher accept no liability for the use or misuse of any of the information presented in this article. This article is presented for informational purposes and is used at your own risk.
Author: Bob Sherman
Publisher: Bobby's Craft Boutique Inc.
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