What are wax additives? Wax additives are different ingredients that you can add to your candle waxes in order to create a cosmetic effect or to change the properties of the wax itself. Using additives can be helpful in that they can solve a variety of different problems that you can run into when making candles. If a particular kind of candle is just not working out, try an additive. The main issue to keep in mind is that additives can introduce new problems into the candle making equation and as such it is recommended to start off adding as little as possible.
The second problematic element of using wax additives is that many have higher melting points than wax making it necessary to melt them separately. Sometimes beginning candle makers have trouble mixing these separate ingredients together as they don't know a key secret - try adding a little bit of wax into your additive before you start melting. Later, when the two products are combined you will see much less separation.
Here is a list of common wax additives as their uses:
Stearic acid is actually a refined animal fat. While not an acid in the traditional sense, it will degrade rubber molds and oxidize copper pots.
Vybar increases candle hardness without also making them brittle. For this reason vybar is commonly used in making taper candles. The other main benefit to vybar is its melting point - sold as either Vybar 103 (melts at 160 degrees Fahrenheit) or Vybar 260 (130 degrees Fahrenheit) - as it is low enough to melt in the same pot as your candle wax. Other benefits attributed to vybar include the ability to add additional fragrance and increased wax opacity.
Unlike vybar, polymers have a high melting point (above 200 degrees Fahrenheit) and thus must be melted separately. The main advantage of using polymers is that the addition allows one to make brightly colored candles by increasing the opacity of the wax. As there are a variety of polymers on the market it is best to read the package to decide which one you want to use for your project. Each one will have different benefits and melting points.
White petroleum is known for increasing the softness of wax and for increasing retention of fragrance oil. This can be an advantage when making container candles as it reduces how much the wax shrinks after cooling. White petroleum is also a common additive when making carved candles for this same reason.
Microcrystallines are essentially what is leftover when oil is removed from petroleum. There are a variety of different blends one can buy but the types break down into two categories - those that increase the elasticity of the wax and those that make wax harder.