This the 3rd post of a 6 part series discussing the management and fabrication of human figures. This month we’ll be discussing the process of life casting and its place in creating a figure.  We tend to be a little sloppy when we use the term life cast, often using it as a substitute for “figure.”  Some figures are completely assembled from life casts but most are a combination of sculpted and life cast pieces and some are totally sculpted with no life cast components at all.

The term “life cast” refers to the process of making a mold of a body part from a live model. Life casting is preferable to sculpting whenever a suitable model is available.  Life casting is an exact reproduction. The level of detail and scientific accuracy life casting produces is impossible to completely achieve by sculpting.  The most common use of life casting is for hands and heads. If the figure being produced is of a young child, member of a historical ethnic group, or a historical person the head will most likely need to be sculpted instead of life cast.

Any parts of the body that are not covered (hands, exposed arms, legs, torsos) should be life cast.  Parts of the body that are clothed (feet, torso) do not need the detail provided by life casting and can typically be fabricated less expensively by carving from foam.  (I will discuss foam carving in more detail in part 4 of this series.)

Life Cast Process

Molding

The first step involves creating a single use mold by applying a medical grade alginate to the body part (hands and heads are most common) needed for the figure being fabricated.  The body part being molded is completely encapsulated in the alginate to create a full 3-dimensional mold.  If a head is being molded the nostrils are left uncovered.

Mold Jacket

After the alginate begins to set (approximately 10 min) a layer of plaster bandages are applied to create a jacket for the alginate mold.  A continuous seam is created while applying the bandages so the “jacketed” mold can be removed from the body part.

Once the alginate and plaster is set (approx. 30 min) the alginate mold, which is very soft, is cut as needed and the mold is removed from the body part.

Casting

The alginate mold is very fragile so ideally a cast is created immediately. The other advantage of casting immediately is it provides the opportunity to remold immediately if the mold is determined to be defective. The mold is partially filled with a liquid resin and a rotational casting machine is used to create a hollow cast.

A hollow cast reduces the weight of the cast but more importantly allows armature to be built inside of the figure.

The key point to keep in mind regarding life casting is that an exact replica is being created of the approved model in the pose and expression also approved. The casts are not meant to be modified and requests to do so will typically result in a change order. The more restrictive nature of life casting, versus sculpting, is worth it because of the level of realism that can be captured by life casting. I hope this clears up what exactly life casting is and how it is used to create all or part of a figure. I look forward to your questions or comments.

Continue to Part 4