Lampblack Ink

Choose a candle color to coordinate with the purpose of your spell. (Green for money, for instance.)

Carve and dress as desired. (This means carve symbols or words into the candle, and annoint with essential oils that are appropriate to your purpose.)

Hold a spoon over the candle flame until black soot forms. (This takes a while; it's a time-consuming process requiring patience.) This soot is lampblack.

When sufficient lampblack has been produced, carefully tap it off the spoon and into a bowl.

Add spring water or wine, drop by drop, to dissolve the soot and then add gum arabica to thicken the ink.

Source: Element Encyclopedia of 5000 Spells