ased on practice, we divide the oil production methods into 3 categories: Soak; Steam distillation and Injection

But despite conducted according to any method, the manufacturing process has the following general points:
- Essential oils obtained have natural fragrance materials.
- Process must conform exploitation material.
- Essential oils must be obtained from the material thoroughly, with the lowest cost.
Principles of extraction of all the above methods are based on the properties of essential oils such as:
- Volatile.
- Alluring under steam at temperatures below 100oC.
- Easily soluble in organic solvents.
- Easy to be absorbed immediately in the air.

1. Dipping Method
This is the oldest method of producing oil, used for thousands of years. To create an herb oils with best quality, all kinds of flowers such as jasmine, rose, orange blossom is spread out on a tray covered with a layer of oil dilution. Processes that oil becomes saturated with fragrance called "separation methods flavoring", and only after several months they keep adding new process impact using a solvent to separate the aroma substances. This process is very meticulous, thorough and requires a long time.

2. Steam distillation method
This is the main method for extracting essential oils from plants. The type of plant essential oils contained in large vats and boiled under high pressure. Aerosols containing oil is cooled and distilled to one or more times to concentrate the product.

3. Injection Method
Essential oils oranges, tangerines, grapefruits are extracted by this method. Simply peel squash, contain many parts most drops. With the squeeze method, one can get full off of vegetable oil.

In addition to the basic method above, it is now applied to scientific and technical progress for extraction of essential oils such as supercritical CO2 method, ultrasonic method, microwave method. The advantage of this method is the extraction of oil is much better, in faster time.