Oil is produced from a variety of seeds that have to go through a number of steps for the extraction to be completed.  These steps vary depending on the extraction process which can either involve mechanical or even chemical extraction. These two extraction methods are the most common with the chemical method sometimes being preferred more than the mechanical method. For large amounts of oil to be extracted from seeds in an oil mill plant using mechanical extraction, the two processes that they have to go through is the pressing of the seeds until all the oil flows out. There are a number of machines used such as the oil press to make sure that the extraction is successful.

However, the extraction can also be done using chemicals such as hexane which are said to be effective in the ensuring that there is no oil that is lost through wastage. Most times the chemical extraction is done as a backup of mechanical extraction in a bid to ensure that there is no remaining oil left in the seeds. It is at this point that the question, “How is oil refined?” becomes relevant especially since chemicals have been used in the extraction process. To refine oil, there is a process known as solvent extraction that removes any chemical that may have been left in the oil. Furthermore, if there are any remnants of the seeds they are eliminated as well so that the refined oil is as pure as possible.

Nevertheless, if mechanical extraction was the only process the seeds went through then the oil can be refined by filtering or skimming over the surface of the container that holds the oil and removing any impurities that may make the oil inedible.