Investment casting has become a very complex industry with newer waxes with a far more complicated makeup than those used a thousand years ago. However, the basic three types of wax are still as effective as ever for simple investment casting. You can purchase the three stalwarts---beeswax, paraffin wax and petroleum wax---at quality art supply stores. Beeswax is literally produced by bees, and both paraffin wax and petroleum wax are carbon-based products with the main difference between them centering on the length of the carbon chain of molecules.
These waxes are a highly specialized form created from resins and petroleum products by highly complex chemical engineering. Industrial waxes fill the needs in investment casting that the simple beeswax and paraffin variety cannot meet. Use emulsified pattern wax---a highly recyclable variety---when you need an easy removal from the die cavity. Runner wax is itself a recycled wax; its main benefit lies in its strength when you need a hardier product for a more difficult casting. Use specialist wax for producing products meant for assembly. The standard and most versatile of the waxes is called a filled pattern wax because its features allow you to use it in any type of casting.
Sometimes flaws occur in products made by investment casting; you can use specialized waxes to repair these flaws. For example, you can use a cream-type wax to resurface abnormalities that appear on the surface of the finished product. These types of waxes are simply called repair waxes; the primary differences between them lie in their melting points and their ability to adhere to other forms of wax.