Chilling the skin with an ice cube of 1:1000 aqueous benzalkonium chloride (Zephiran) gives quick, painless, superficial anesthesia plus antisepsis. No other steps are necessary prior to minor electro-surgery. Numbing a proposed injection site with an ordinary ice cube is an old pediatric procedure. Prior to electrosurgery, however, an alcohol sponge could not be used to wipe the skin without a flash fire from the spark. Breaking the skin contaminated with unsterile water from an ordinary ice cube might be objectionable.
To overcome these objections, I make ice cubes by diluting 4 cc. of stock aqueous 12.8% commercial concentrate of benzalkonium chloride with 500 cc. of water. This makes one tray (14 ice cubes) of 1:1000 benzalkonium chloride solution,* costing 1/5¢ per cube. An added drop or two of any dye (gentian violet, Parker 51 ink, methylene blue, etc.) protects the staff from inadvertently drinking benzalkonium chloride ice cubes