Protecting the skin from the heat

Laser light is absorbed by the melanin present in the hair, which is shaved before the treatment in order not to waste the energy and not to heat the skin pointlessly.

By luck, the hair store the heat, while the skin cools down very fast. This interesting property is used to heat up the bulb without damaging the skin.

Once heated, the hair frees the heat energy it has stored. This energy spreads throughout the hair and destroys its lower structures, the bulge and the germinal matrix, where new hair are synthesized.

The outer layer of the skin (epidermis) is the laser's weak point: hair have to been burnt in depth, but without damaging the skin surface.

This is why a third rule of laser hair removal exists: be sure the laser is equipped with an efficient skin cooling system. Side-effects (superficial burns and pigmentation disorders) only occur if the skin is affected.

The goal is to keep the skin temperature low by cooling it down actively. The first cooling systems consisted in ice or gel applied directly on the skin. Then, more elaborated techniques appeared such as the projection of cryogenic spray, or cold air blown constantly.

Skin cooling devices are both known to be space wasting and efficient. These devices have become nearly as big as the laser devices themselves along with the advances in technologies. But they insure both tolerance and efficiency. They also numb the skin by lowering the skin temperature.

The CrioJet blows a constant air flow at a -60°C temperature. It provides skin cooling before, during and after the shot, as well as comfort for the patient.

There exist several types of skin complications related to laser. The most obvious being burns, which are always very superficial. But pigmentation disorders may also occur, such as hypopigmentation if cells synthesizing melanin (the melanocyts) are destroyed, or, more frequently, hyperpigmentation, that is the development of dark marks. With decent material, these accidents almost never happen on light skins.

On darker skins, laser acts like prolonged exposure to the sun and can induce variations in skin pigmentation. These marks generally disappear rapidly, but it can sometimes take a few months before the skin gets totally clear!