How is the skin formed?
The skin is a superposition of layers: epidermis, dermis and hypodermis. These layers form an elastic covering with small openings, the follicles (through which the fat is expelled) and the pores (through which the sweat is expelled).
The epidermis is a thin layer whose thickness is barely thicker than that of a leave. It is over the epidermis that we spread our cosmetics.
The dermis contains the famous proteins of collagen and elastin responsible for keeping the elasticity and youth of the skin.
The hypodermis is a layer made up of adipose cells.
Generally, the stratus conium is compared to a brick wall in which the corniocytes are the bricks, linked by a lipid type cement. In this cement are the poly-unsaturated fat acids and cholesterol. The quality of the cement is fundamental, since it allows the retention of water in the corneum cells and, in general, prevents the transepidermic leaking of fluid, which is constant. That is why it is important to apply on the skin cosmetics reach in lipids such as oils and vegetable butters.
taken from the Slow Cosmetique book