This is how CBD-rich medical marijuana oil extractions are carried out using 100% pure Ethanol (do not use common alcohol) and cannabis (Critical Mass CBD by Dinafem on this occasion). The CBD levels obtained were remarkably high and the extraction had a roughly 2:1 CBD/THC ratio.
The extraction is generally dissolved in oil or in other substances fit for human consumption.
The filtering and cleansing process is of utter importance so that all unwanted residue is removed and the extraction is as clean as possible.
This video shows the steps involved in the elaboration of an extraction as well as the analysis of CBD, THC and CBC levels conducted by the lab staff.
Watch out when handling flammable substances!