A highly specialized type of makeup is prosthetic makeup, sometimes called FX prosthesis. Prosthesis, from the Greek word meaning “addition” is an artificial device created to replace a missing part of the body. By extension, it has come to mean the alteration of a person's appearance and is an essential part of the stage, television and movie industries requiring specially trained makeup artists. FX prosthesis involves techniques in sculpting, molding and casting to produce highly sophisticated cosmetic effects. It also demands creativity and artistry to create the look to be crafted by the makeup technicians.

Dick Smith is credited with revolutionizing prosthetic makeup in films like “Little Big Man”. In FX prosthesis, a mold of a part of the body is made out of silicone rubber to serve as the base for sculpting the prosthetic, a process known as “lifecasting”. Because this mold is supple and flexible, another mold made of plaster or fiberglass is made and placed on top of it for support.

This mold is filled with gypsum cement to make a “positive” mold on top of which the form of the prosthetic is sculpted in clay. It is important for the edges of the clay to be as thin as possible. After sculpting is done, the prosthetic material of foam latex gelatin or silicone is cast into the mold and cured.

The airbrush is an important part of prosthetic makeup. At its simplest, slight changes in a person's look, such as a scar, pock marks or a tattoo are applied using standard airbrush makeup techniques. In the case of prosthetic makeup a more complicated process is needed. A Gravity Feed Single-Action internal mix airbrush is used for this purpose. In makeup work, however, a Single-Action airbrush means that the air is flowing through the airbrush. This is sometimes referred to as a “Cosmetic Single-Action” airbrush. The only function of the trigger is to adjust the color volume and the width of the spray pattern. The air continuously flowing through the airbrush prevents the makeup in the brush from drying up even while the makeup is not being applied. The internal mix type produces a fine, soft spray and gives the artist full creative control.

When the prosthesis is removed from the mold, it has the uniform color of the prosthetic material out of which it was made. This means that all the details of, for instance, an alien face or a monster, must be painted on the prosthetic using an airbrush. The airbrush is the perfect tool for creating makeup that looks natural and realistic. This is specially important when an imaginary look is created as is the case in horror movies or sci-fi presentations. Because close-ups are commonplace, the joint between the prosthetic and the performer's natural skin must be flawless and only the airbrush can produce this blend.

The next time you wonder how your favorite movie star could look so old or ugly, or when a strange-looking face jumps out of the screen and scares you, it's the airbrush that made it largely possible.