As internet search data shows, soy wax has been one of the most popular natural alternatives to paraffin wax in recent years. It is easy to use and absorbs fragrances relatively well, but unfortunately it also has a few drawbacks: it is prone to frosting, uneven burning and yellowing.
If we know what triggers these problems, most of them are relatively easy to remedy. Let's take a look at what can cause soy wax to turn yellow!
Soy wax can yellow in two different ways, and these two phenomena are caused by two very different processes. Either the bottom layer of wax on the candle can turn yellow, or over time the whole candle can become yellow.
When fragrances (be it fragrance oil or essential oil) are added to the melted wax at the wrong temperature, they will not be able to mix properly. There is a risk that the heavy fragrance will sink to the bottom of the pot where it will form a yellowish layer in the solidified candle.
Not only is this aesthetically unpleasing, it also impairs the scent throwing ability of the candle, as the upper layers will not contain sufficient amounts of fragrance, and the proportion of wax in the bottom of the candle will be too low to allow the candle to burn properly.
For soy wax, the correct temperature for adding fragrance is between 180-185 ℉ (82-85 °C). You also need to make sure that the added essential oil is well mixed into the melted wax, and that you do this without mixing in bubbles.
It is also important to keep to the correct proportion, not adding too much or too little essential oil to the wax, as both extremes can impair the burning quality of the candle.
We have probably all experienced the phenomenon of the spines of books stored on sunny shelves fading over time. The same thing can happen to our candles: if we have used dyes to make them, they lose their brightness after a few months, and white, untinted soy wax can turn yellow from UV exposure.
Since UV rays are part of natural sunlight, the best way to protect against them is to keep your candles out of the sun. If you don't just want to admire it when you use it, but want to keep it as a permanent decoration in your room, you can reduce the likelihood of yellowing by adding a UV inhibitor to the molten wax.
High levels of vanilla fragrance oils can also lead to yellowing effects similar to UV rays. These can discolour the wax within a day or so, so it is a good idea to add a little ivory dye if you are using such fragrances.
The yellowing of soy wax can be almost completely avoided if you prepare your candle properly and add the right additives to the wax. It is therefore very important to take the necessary precautions when making candles!