It's about time that some herbal information made it up here :P
I'd like to touch on not only the technical difference between macerated and essential oils, but how their effects vary in ritual and spell craft.
Okay, first of all (and most of you already know this), but an essential oil isn't really an oil at all, having little or no fatty substance . By-the-by, if you're buying essential oils from a metaphysical store, and they have a slightly greasy feel to them, more likely than not, they have been cut with grape seed oil, which has no real scent of its own, making it a popular carrier oil. Just a heads up.
Sorry for the detour, just thought that it bore mentioning! Okay, essential oils are the volatile oil/essence/heart of a plant. They can be extracted using steam distillation, alcohol/solvent extraction (necessary for some plants that won't react to steam, or for tough root-based essential oils), or through a labor-intensive process called enfleurage, in which fresh blossoms are delicately pressed into a screen that is first layered with fat. The flowers release the full range of their precious scent as they die, and the fat is scraped and refined. Enfleurage created essential oils, while they tend to be terribly expensive, are also more layered and complex in their scent.
While magical practitioners as a rule, tend to enjoy making their own tools, most of these methods are beyond the scope of the average person. Creating essential oils, even in minuscule amounts, takes a lot of raw plant matter (land, ability to harvest, or access and ability to purchase large amounts of fresh material locally), a large monetary investment in equipment and tools, time to experiment and get a pleasing end result. So many variables go into creating a proper essential oil; scent varies dramatically depending on the time of day that the plants are harvested, heating temperatures during distillation, etc.
Okay. Maceration, in this sense, refers to covering dried plant matter with oil, and allowing it to release it's scent, medicinal, and magical properties into the oil. Anyone with access to dried herbs, or a bit of a garden to grow and dry their own, can do this.The end result varies dramatically, depending on what you are using. Dragon's Blood resin, for example, stains the carrier oil to a brilliant, bloody red almost immediately, and releases its potent scent very well by this method. I recommend a bit of sunlight to help it along.
Others, such as licorice root, have almost no perceivable scent, and if you are using a strongly scented carrier, such as olive oil, may be buried completely.
Don't be ridiculously disappointed if your oils aren't strongly scented. They still pack a magical wallop, and are far superior to those pretty packaged fragrance (read, plastic) oils at the messy-physical store.
A lady recently contacted me about making macerated oils, and said that she was having trouble finding info on it. So, in the interest of helping along the magical herbalist, what follows is a fairly detailed explanation of making oils, and keeping them from going bad:
Sterilize your jars thoroughly. Very, very important. Wash them with antibacterial dish soap, allow them to dry, and then another wash with alcohol. Dry them out with a hairdryer or heat gun. Fill the jar about halfway with your favorite herb, cover with your chosen carrier oil. Use extra virgin, cold extracted oils. Cap tightly, and let it macerate for about a week and strain. If the scent or effect still isn't strong enough for your taste, add fresh dried herbs to the strained oil, and perform the same process over again, until you get your ideal results. During the last straining, add a bit of Vitamin E oil, benzoin, or tincture of benzoin for preservation.
Macerated oils are delightful to use in spell craft, and have a much longer history of use in magic than essential oils do. Hoodoo Condition Oils are traditionally made by this method, though many modern practitioners pump up the effect with essential oils.
Essential oils have gotten a glamorous reputation lately, partly because of their exorbitant cost. Many believe that they are more powerful, as they contain the essence of a plant. Macerated oils are a bit homely, not having the noticeable scent that EOs do. Both are quite effective in spell casting, but layering and tailoring effects is more effective with the soaked versions (they play well with others). They seem to hold a greater amount of energy, and blend well with each other. EO's tend to work very quickly, and are unsurpassed if your intent lies on a highly psychological level; it is similar to the difference of medicinal herbalism and aromatherapy. One isn't necessarily BETTER than the other, except in the condition and the individual they are treating.Magic is nothing if not personal, and specific. Natural perfumery is well worth study; learning which EO's blend well with each other, composing scents based on base, heart, and top notes, as well as using your magical training to tailor intent.
Just please, please, always use the natural varieties. Fragrance oils have no magical power in and of themselves, and whatever results are the outcome, are all you, with a bit of the placebo effect thrown in.
Almost forgot to mention. There will be an oil or tincture that you will struggle with. Mine was basil. No matter how clean the bottles were, no matter how carefully, thoroughly dry the basil, it would always mold on me. It took me two full growing seasons to master the art of basil tinctures and oils; don't be afraid to experiment until you find what works for you :)