Base oils are divided into four categories:
Synthetic base oils are not directly from petroleum refining, but are synthetic base oils obtained from petrochemical products.
Hydrogenated base oils are base oils obtained by hydrotreating mineral oils.
Solvent Refined Mineral OilMineral oil type base oils obtained by solvent refining.
Other base oils do not belong to the above 3 classifications of base oils.
Standard base oils refer to base oils produced according to the relevant standards, such as the paraffin-based neutral oil standards, intermediate base and cycloalkyl oil base oil standards, and base oil series standards issued by SINOPEC earlier.
Expanded Information:
Base oils are called by some as medium oils or carrier oils, and the single essential oils can't be smeared directly on the skin (except for lavender and tea tree, which can be dabbed on with a cotton swab on a small area), and they have to be diluted in base oils before they can be used extensively on our human skin.
Many carrier oils have medical properties in their own right, and growing in plant seeds all over the world, we can make all kinds of plant oils. There are several hundred species of plants whose seeds produce oils, only a few of which are used for commercial purposes.
Base oils used in aromatherapy are cold-pressed (processed below 60 degrees Celsius), while edible oils, such as soybean oil, are extracted at temperatures above 200 degrees Celsius, and are the kind of edible oils you usually see on the shelves of supermarkets.
Reference: