Vacuum purge
From Wiki Weed
After extraction, most concentrates require further refining in order to remove the solvent which is remaining in the product. In order to do this, concentrate makers have utilized vacuum ovens and devices which serve to reduce the atmospheric pressure on the concentrate, which speeds up the process of removing the solvent and allows it to happen at a lower temperature than would be possible at normal pressures; this enables more terpene preservation, as they evaporate above certain temperatures.
