Article – Let Stearic Acid Help Your Candlelight Last Longer

Stearic acid a.k.a. stearin usually comes in granulated or powder form and is a candlemaker’s best friend. Interestingly, it was a 19th Century chemist, one Michel Eugene Chevreul, who discovered that animal tallow was in fact, a compound made of two acids – oleic and stearic combined with glycerine. When the glycerine is removed from the compound, stearin is the result.
Tallow is animal fat but distinguished from the so-called ‘killing-fat’ obtained during the slaughter of the animal it comes from the ‘cutting fats’, which are removed from organs and the carcass. When the tallow is heated it turns to oil. This is the oil that is used in food and in candles and in cosmetic creams and regular body soap and of course, candles. In the latter two applications, it is the stearic acid makes the soap and the candle wax hard.

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Only 10% of Stearic Acid is needed for 90% wax to perform its particular magic. It unmoulds more readily, which is a huge headache halved.  Melting even a small amount of stearic acid in with powdered candle dyes helps the colour disperse evenly throughout the candle. It also creates the lovely pastel look to the colours. Adding 2% stearic acid to the paraffin wax reduces seepage if you’re using a heavy fragrance oil. But the most common reason to use the acid in candles is that it achieves a glossy finish and the hardening factor makes it take longer to burn and it magnifies the scent.
The hardening effect of stearic acid is especially wonderful for those preferring soy candles now that a vegetal source has become popular. Palm and coconut stearic are favourites although bear in mind that it will elevate the melting point of the soy, so keep an eye on things.
In short, stearic acid is a vital part of our lives, it’s in our food, our cosmetics and in the candles that create the ambience for all our special celebrations. Long live stearic acid!