Soy Wax Polymorphism

EcoSoya logo

Most of our customers know the best-in-class benefits of EcoSoya soy waxes and the unique characteristics of soy wax: cleaner, cooler, and longer burning, made from renewable resources, biodegradable, easy to clean, etc. Another distinct trait of soy wax is that it experiences polymorphism, which means it is polymorphic.

What is Polymorphism?

What exactly is polymorphism? It pertains to the structural characteristic of the soy wax which has the ability and desire to form different crystal types while retaining the same chemical composition.

These various types of crystalline structures can form when the candle cools from a molten state to a solid candle. The types of crystals that grow in the candle may be influenced by the components of the candle and its environment. Not only can more than one type of crystal form in the candle, but the existing crystals can continue to change over time as they seek what they consider to be a more stable structure for the environment they “live” in.

Simply stated, when the candle system and surrounding environment encourage the growth of different types of crystals, the effects can be seen in the aesthetics of the candle. In the worst cases we see this as “bloom” (white frosting), the cauliflower effect, rough/grainy top, or white lumpy tops.

An example of polymorphism can be found in chocolate. As chocolate ages the outside of it becomes white or “frosted”. The aesthetic and texture changes but the chocolate itself has the same chemical composition as when it was first made.

The Conditions of Polymorphic Crystalline Growth

Numerous conditions affect crystal growth, such as: pour temperature, ambient temperature during cooling, humidity, candle storage temperature, fragrance, dye, anything added to the wax, and of course wax composition, to name a few.

The crystals are especially sensitive to temperature changes. In fact, the period from when the first crystal forms in the molten candle to when it solidifies is the most critical. Maintaining an even temperature during this time is necessary to encourage proper crystal growth. Candles made with EcoSoya® container waxes are best cooled at temperatures of about 68°F to 80°F.

Soy Wax Polymorphism and Pouring Candles

When pouring candles, it is best to avoid a large temperature gradient between the center of the candle and the outside walls of the container. Since different types of crystals like to form at different temperatures, a large temperature gradient can encourage different crystal growth both when the candle is cooling and when the candle burns.

In the food industry, items such as chocolate are shipped in temperature-controlled trucks to maintain their crystal structures, a luxury we in the candle industry don’t have. Therefore, it is crucial to find a pour temperature that promotes even temperatures throughout the candle while the candle is cooling.

It is clear that while a different crystal structure may not alter the soy wax chemically, it does play a huge role in the overall appearance of a candle. Although it may require some testing, the optimal crystal structure can be achieved. By finding the best wax components; fragrance, dye, pour temperature, etc. for the candle, you can minimize the effects of polymorphism.