High frequency uses alternating (Tesla) current to conduct energy to a gas when it is ignited. Glass electrodes contain either Argon (violet) or Neon (orange) gas. When light energy is given off, it forms electricity around the electrode. When the oxygen, naturally present in the air around the electrode is electrified, it forms ozone. It is especially useful after the extraction phase of a facial because it kills germs, dries excess oil and increases healing.
During your facial your esthetician will perform extractions and then will use high frequency as a bacterial inhibitor. She will place a gauze over your face so that more oxygen will surround the glass electrode and more ozone is formed and the greater the effect. She will then move the electrode lightly across the gauze in circular movements. The machine may make a noise similar to an electric fly zapper but you will not feel any current just the electrode moving on your face.
She may focus on areas that are broken out trying to kill the bacteria and dry the oil in the blemish. After the high frequency she will continue the balance of the facial.
For clients with acne it is beneficial to have a high frequency application every couple of weeks. That coupled with following a home care regimen with specific acne targeted products and extractions should produce results.