the best part ... Vayikra 18:30
Candle waxes are made from a variety of fats, oils and waxy-like animal, insect, plant and rock substances.
Ancient civilizations primarily used tallow derived from animals to produce wax for burning.
"A tallow candle, to be good, must be half Sheep's Tallow and half Cow's; that of hoggs mekes 'em gutter, give an ill smell, and a thick black smoak" ... Anonymous, 18th century
Beeswax was introduced as a candle wax in China between 618-907 CE and in Europe during the middle ages. Extracts from tree nuts, the Coccos pella insect and the fruit of the cinnamon tree were used in Japan in the 12th century. During the 18th century, oil from the head of the sperm whale was made into spermaceti wax. Chemically synthesized waxes were created during the 20th century as were waxy gels, vegetable bases, soy and palm oils.
All waxes are primarily hydrocarbons and when burned, emit some carbon (soot) due to incomplete combustion. There is no such thing as a soot-free wax.
When a candle is burned, the flame oxidizes the wax producing water, carbon dioxide, light, heat and soot. The flame that we see flickering off the wick of a candle is the luminescence of non-combustible carbon particles that are very hot but incompletely burned. These carbon particles combine and form soot. The flickering flame of a candle is composed of the glow of rising carbon particles which will combine and cool into black soot. Adding unsaturated hydrocarbon fragrance oils softens candle wax to produce cooler burning. Cooler burning produces more soot.
Soot is associated with respiratory disease - submicron soot particles can penetrate deeply into the lung. The carbon core of soot can act as a carrier of many kinds of toxic molecules. It also can deplete indoor air of the healthy negative ions responsible for removing harmful air contaminants. Negative ions in healthy indoor air may also fight infection, enhance mood, improve appetite and sexual drive, attenuate allergies and migraine headaches, support the body's resistance to disease in general, increase the ability of red blood cells to absorb oxygen, and promote alpha brainwave activity which augments higher level awareness.
While the flame is made of glowing soot, fire itself is nearly invisible to the naked eye.
So, when choosing candle waxes for ritual purposes, consider the flame and the fire and their respective roles in the ritual, when making a choice.
Related entry - The Science of Scent