Nerve photo (Schuster, 1992)
James Schuster is a Wisconsin dermatologist who has prepared several videos and slide presentations on hair removal. Dr. Schuster performed several controlled tests of electric tweezers to demonstrate that the devices cannot perform as claimed.
The reason tweezing, waxing, laser, and electrolysis are sometimes painful is because each hair has a bundle of nerves surrounding the lower follicle. Plucking a hair tears the tissue near the root, which can set off pain sensation in these nerves. The energy required to remove hairs with laser and electrolysis can also cause these nerves to register pain. The reason so-called "painless" methods such as electric tweezers do not usually hurt as much is because they do not deliver enough energy to the root of the hair to cause lasting damage.
(slide courtesy of James Schuster, M.D. Reprinted with permission.)