http://www.fxsupply.com/life_casting/casting.html
About Face and Body Casting:
Alginate, plaster and plaster bandages are being used more and more in a variety of applications: A face and head cast is the foundation for foam latex makeup, plaster casts of hands are now sold regularly in art shows, and plaster bandage "sculpts" have been crafted by artists for more than 30 years. When combined as a process, these three basic materials can be used to make casts of exceptional quality. The head cast pictured here was used for a melting vampire in the movie "Nightfall" produced by Spinning Reel Films. Please review the following notes before using any of the materials featured on this page.
It is a common and dangerous misconception that plaster is used to make life-casts of actors' faces for use in special effects. Because plaster becomes rigid, it is difficult to handle and remove, especially from body hair. Because of its weight, it will deform the face. We recommend artists use a prosthetic grade alginate. Alginate is a rubbery material derived from seaweed. Dental alginate can be used but you will only have 50 seconds of working time and you must use cold water which is uncomfortable. We recommend a "Warm-water slow-setting alginate" which has been buffered to set in about 5 minutes. This gives you plenty of working time and because warm water can be used, it is much more comfortable to wear. Use plaster bandages as a "back-up" to the alginate and use the plaster only for the positive cast. If you are doing a full body cast you can use a high quality plaster bandage to pick up detail on the arms, legs and body. Use silicone or alginate in detail areas like the hands, feet and face.
Glossary of Materials and Terminology used in Life Casting:
ALGINATE, also known as PROSTHETIC GRADE CREAM. A powder, that when mixed with water transforms into a rubbery material. Typically Alginate can only be used once. Dental Alginate is used by dentists to cast teeth. Slo-set (Prosthetic) Alginates are used to cast face, limbs and body parts. Dental alginates set in 50 to 60 seconds. Prosthetic alginates set in three to ten minutes. Sorry, prosthetic alginates are not flavored.
BALD CAP, BALD PATE, BALD WIG. A stretchy cap that is stretched over the head to protect the hair during casting. Made from Glatzan or latex rubber.
CAST. The final piece taken from mold. A POSITIVE. Usually made from Casting plaster, Hydrostone, foam latex, slip latex, UltraCAL 30 or other material. Cast can generally be used to describe the entire process, for example: To do a body cast the artist would prep the model, make a mold and take a cast from the mold.
CASTING PLASTER. Very much like Plaster of Paris except that it has a slower setting time. Forms a skin when used in a mold. Used for finished casts. No good for latex molds or for foam latex. Paints well. 2,400 psi.
HYDROSTONE. Gypsum Cement. Hard and strong. Used in high quality art and novelty casting. Can't be worked with a template or formed by hand. Forms exceptional details. Very resistant to water absorption. 10,000 psi.
MEDICAL ADHESIVE. A silicone based adhesive that works like super-glue. Used by professionals instead of spirit gum. Don't use it around the eyes. Don't try to use it without a good MEDICAL ADHESIVE REMOVER. NOTE: For environmental reasons the old Medical Adhesive that we all know and love is no longer available. The new stuff works well but has a different formula. If you order the Ben Nye stuff that we sell we will send you PROSTHETIC ADHESIVE which works just as well.
MODEL. The person or thing which you want to duplicate.
MOLD. A NEGATIVE of the model. In body and face casting the mold is usually made from Alginate or plaster bandages.
MOLDERS' PLASTER. AKA Pottery Plaster. Excellent for molds, especially for ceramics and slip latex (masks). Doesn't form a skin like plaster of Paris or casting plaster. Absorbs water very well after completely dry. 2,000 psi.
PLASTER BANDAGES. The same thing a doctor would use to put a cast on your arm. We use Gypsona Brand Bandages because they are very creamy and flexible. 2" and 6" are the most common sizes used.
RELEASE or RELEASE AGENT. Something that is smeared, painted or sprayed over something else to keep stuff from sticking to it. For example petroleum jelly is smeared over the eye brows to keep alginate from sticking to them. Releases are used for specific materials.
ULTRA CAL-30. Gypsum Cement (looks and works like plaster). Excellent for foam latex molds because of its strength and resistance to heat. Standard of the industry for special effects make-up artists. 6,000 psi.