The process of boiling away the solvents and impurities that are part of the creation process in the production of BHO. This process will produce a pure, safe and delicious BHO. Vacuum purging places the oil under an atomspheric pressure lowering the effective boiling point of each of the compounds. This allows certain ones to be cold boiled away without potentially damaging the others. This process is best performed in a vacuum oven but, if that is not possible one may make their own purging system.