A method is provided for reducing a wrinkle on a skin surface (42). The method includes identifying a person having a skin surface (42) with a wrinkle and in response to identifying the person, positioning at respective sites on the skin surface (42) an array (44) of electrodes (60) coupled to an energy source (46). While the electrodes (60) are at the respective sites: during a first time period, applying energy from the energy source (46) to drive the electrodes (60) to apply radio frequency (RF) current at a first voltage, capable of ablating an epidermal layer of the skin; and during a second time period, applying energy from the energy source (46) to drive the electrodes (60) to apply current at a second voltage, lower than the first voltage. Other embodiments are also described.