Life Casting                                                                                       

 

Introduction.

I have a family of friends who live on a Greek Island and they have to earn a living. The island economy is based on tourists. At the end of every season, after the tourists go home, everywhere closes up for the winter and the population of the island drops by half. It is very difficult to earn money because permits are required to do anything and even a simple permit, can take up to a year to get all the required signatures and government stamps etc.. It was against this background I wondered if Life Casting might be a possibility for them, as it was vaguely related to some of the things they already do.

 

The basics.

You find a beautiful person of the opposite sex,  convince them it would be a good thing for them to remove all of their clothes ..........  and then throw cold wet plaster over them !. 

 

Types of body casting.

Life casting can be subdivided into a number of distinct categories ......

a.    Infant and children.  For infants it is mainly replicating the hands and feet. 

b.    Adult hands.    Lovers holding hands. Family groups holding hands as a sign of unity and togetherness.

c.    Pregnancy Belly casting.    In the simple case, plaster bandage is laid up on the belly and this cast when dry it is the final product. The second version is where a mould is made from the belly and then a casting laid up in this mould, reproducing all of the body detail. 

d.     Glamour body casts.   These tend to avoid the intimate parts of the body and do not always show detail. 

e.     Erotic  body casts.     Erotic body casts show great skin detail and include the intimate parts of the body. Although they can be made full length it is common for them to cover from chin to mid thighs. Two person casts are common, typically an embrace  expressing love rather than sex.

f.    Intimate body casts.    Singles, couples and groups focusing on the sex act.

 

Things your mother did not tell you about.

 Life casting is all about creating a replica of a part of a human body. Why would we want to do this ?. If I asked you what you looked like when you were 18, you might be able to produce a photograph of yourself at that age. Photographs are two dimensional images of what something looks like on a flat surface. Historically statues were originally the only three dimensional means of recording what someone actually looked like. The three dimensional replica gives us so much more information a about a subject than a simple  photograph does.  Holograms are can synthise a three dimensional image but we have a long way to go before they become as realistic as the photographic image or a casting of the original subject. 

Life castings are not a new thing .... the dinosaur fossilised footprints are millions of years old.  Three thousand years ago the Egyptian's practiced the art.  Probably the very first human life casts were invented when the caveman pressed his palm into wet clay. We know exactly what certain people looked like, only because of life casting. Current interest in the art was fuelled by the realisation that anything that is not recorded is lost forever. Now we can record things in three dimensions. For example how small a babies hand is compared with the mother who held it. We can permanently record the joining of hands of people in love ... yes, age will change them, but the life casting remains young forever. Can you remember how your body looked when you were younger? , well now you can. In effect life casting can make your body  as immortal as Venus de Milo ... or Michael Angelo's 'David'. 

In times gone by, lovers exchanged personal items as a remembrance during times of parting. The perfumed handkerchief kept many lonely hearts afloat until they could be together again. Now life Casting enables the most intimate tokens to be exchanged, as an expression of love and commitment.

 

Casts and moulds.

For most women pregnancy is a wonderful experience of creation. The 'bump' as it is now known becomes a source of infinite wonder as the embryo grows inside them into a perfectly formed child and they become very proud of it. I think the current wave of interest in Life casting began with the mothers desire to record everything about this magic moment in their lives. This started the art of belly casting, which has now become very popular. In the early days someone would come along and do it for you, but it became so popular that kit's became available and ladies had 'belly casting' evenings !. The process was very simple. First the subject had to define the area of her body to be replicated and then mask off pubic hair. A 'lacey' slurry coat is then applied to the area and then a few layers of plaster bandage applied to build up a strong shell on the 'bump'. After about 15 minutes the plaster sets and when removed ...  a second industry was started .... decorating belly castings.  Once decorated, the proud mother had a permanent record of the whole event .... something that a failing memory could never erase.

In the above example the body detail was on the inside of the casting and the side presented to the viewer was of the rough plaster bandage layup.  In this application this may be exactly what the mother may want, since it tends to conceal intimate details of the body. For many women this was not enough and they wanted the detail to be seen, warts and all !. This required a different technique. After the first casting, a second casting  had to be made on the inside surface of the casting. This then revealed all of the detail. In this case the first casting became the 'female' mould and the second internal layup became the 'male' casting.  There is sometimes confusion between what is 'male' and what is 'female'. The same applies to the question of what is a cast and what is a mould. In the latter case I can only direct you to the eventual use of the laid up item, ie do you intend  using it as a cast, or a mould ?.

Making plaster casts from plaster moulds, is fraught with the problem of plaster sticking to plaster, it is basically a 'one off' process. Having said that I have often produced dozens of plaster casts from a single plaster mould and got away with it. The secret is to saturate the surface of the plaster mould with Vaseline diluted in white spirit or diluted washing up liquid, for maximum release capabilities. If we want to produce a large number of copies of an object then we need to look at a slightly different process and this involves making a mould of the original item in a more durable mould material. Silicone, latex, polyurethane etc are typical materials. Since these materials tend to be flexible they have to be contained in a rigid casing, which can be plaster, polyurethane or polyester resin with glass fibre reinforcement etc..   

Making a plaster mould and a subsequent plaster casting is a relatively cheap process.  Latex rubber is also a cheap process, but the slow drying time means it cannot normally be used on a live model.  The use of silicone rubber and other high end materials requires one to justify the cost of making a mould in the first place. Usually, the only reason for replication is for commercial reasons and for that reason mould costs have to be amortised against the number of 'pulls'  one can get from a mould before  it wears out. Again the slow curing time means that only specially formulated fast setting rubbers can be used on live models. Silicone rubber compounds are available with a de-mould time as little as five minutes (Skinsil).

Large plaster casts cam be reinforced with jute scrim and body casts with cotton scrim. Chopped strand glass mat works and for extreme  strength a casting can be reinforced with an open weave glass fiber cloth.

 

Model preparation.

Preparing the model begins when the initial appointment is taken. The aim is to make sure that the client feels comfortable about the whole thing and that the way is prepared for maximum success. For example they have to be told not to wear tight clothing before keeping the appointment. There is nothing worse than "knicker elastic" indentations in the skin and having to delay things until they disappear.  

For many clients, having a life cast done may be a unique experience and it pays to explain everything in advance as to what is going to happen, so that they will not experience any unpleasant surprises during the process. Some day someone is going to write about the psychology of intimate processes, but generally a woman can process a woman with no problems. From a man's point of view it is more acceptable to be processed by a woman than a man. If a woman is to be processed by a man, then a female assistant should be present. 

Before moulding anything we must make sure that we can separate the finished mould from the model. Almost all mould  materials used on the human body do not actually require a release agent to be applied to the skin.  However, nearly all mould materials will adhere to long body hair. The usual advice is that body hair should be trimmed to be no longer than a quarter of an inch long and then plastered down with a petroleum jelly, such as Vaseline, to stop the casting medium flowing into the body hair .... and locking onto it as it sets.  Many women have short fine hairs on their arms etc and these can be plastered down onto the skin with a release agent such as Vaseline or KY jelly. If in doubt test a small area first ... preferably on yourself. Selective masking can also be used , but unless you know exactly what you are doing ... I offer the following advice ....

Stay well away from any area's the model is not prepared to shave in advance.

One of my fondest memories of life casting was an illustrated article by a famous sculptor on making a plaster body cast. Everyone was smiling up till that magic moment when they tried to remove the cast !. The plaster had obviously 'leaked' into the pubic hair of the amateur female model  ... and the look on the sculptor and his assistant's face was pure horror. The look on the models face was a mixture of pain and extreme hilarity at the absurd situation she had been talked into. I have no idea if she ever sued for the return of her pubic hair !.

 

Plaster Working time.

The length of time to produce a body cast is a compromise between making it as short as possible for the comfort of the model ..... and the actual time required to layup a strong,  useable cast. Generally two operators require a minimum of 10 - 15 minutes is required to lay up a torso sized cast;  that is from the chin to mid thighs.

As the plaster sets it generates heat. The only way to minimise the heat is to restrict the thickness of the casting. This means that one cannot simply fill body voids such as breast overhangs and the cleft between the thighs with solid plaster. Instead these contours have to be laid up with a plaster bandage lamination that is no thicker than that used for smooth flat areas such as the stomach, back and upper breast areas. It is normal to add reinforcement around the edge of a casting to strengthen it.

Plasters are available that typically set with times between approximately 5 and 30 minutes. Retarders can be added to the plaster to increase setting times.

 

Direct plaster casting.

The only part of a casting that we will normally see will be that which was in direct contact with the skin. It is therefore important that this surface is free from defects such as air bubbles etc.. To do this we have to make sure that when we put the first coat of plaster onto the skin, we have to make sure that it is continuous and without any voids or air bubbles. The easiest way is to use bare hands to first apply a film of plaster on the area to be covered. If this is not acceptable then a soft layup brush can be used to apply the first and subsequent coats, applying a stippling action in areas of detail, such as around the nipples, breast over- hangs, inside belly buttons, armpit and pubic clefts, lips, ears, eye folds, nose and face creases etc. 

 

Angle of the dangle

Any woman will be able to tell you that as she slowly leans back, the breasts rise and separate. They also seem to get smaller and overhang reduces, as the mass settles down over a larger area.  A similar thing happens when a woman raises her arms. So by arranging the position of the models body we can modify the shape of the models body. This lead to the development of the casting  board, which can be tilted back a few degrees. They also introduced two moveable padded rests for the models arms, which can be set in any position. The casting board not only allows the models body to be adjusted to the best position, but it is also makes things more comfortable for the model during the casting process. When casting the rear of a torso, the back is much firmer and it is often possible to cast slim models lying face down, without any noticeable body distortion. 

 

Hair.

If you are making a casting of a bald man then one does not expect the finished product to have a full head of hair. On the other hand if we are making a casting of a woman's head and she would not expect a bald casting !. The compromise is usually to pull the hair back into a pony tail or bun, and then plaster it with Vaseline to stop the hair absorbing the liquid plaster. If the subject does not normally wear her hair that way, then the end product is not going to look very realistic !.  The usual approach to this problem is the model the hair separately and add it to the life casting.  Another approach is to make a latex 'wig' that the model can wear when the life casting is made. Examples of both methods can be seen on You tube. 

 

Eyes.

We have a similar situation with eyes.  When making the casting they will be closed. Again this is OK if you are modeling a sleeping client. However for the most realistic life casting the eyes need to be open !.  The only way we can do this is to model the eyes open after the casting has been made. This is easier to do on clay than plaster. We can layup a clay casting inside a mould of the life casting or slush mould slip inside the mould. When the clay is firm (but not leather hard) the eyes can be dug out and false eyes inserted into the clay. The eyelids then have to be modeled over the upper and lower parts of the false eyeball. A mould is then made of the head and a plaster casting then made as the end product ... complete with hair .... of course !. A demonstration of this method can be seen on You tube. Imitation glass eyes are available as complete spheres or oval sections. My own opinion is that oval section eyes are easier to use. Some have the outline of the pupil and iris engraved on the eye ball. One set of imitation eyes can be used for all adult heads and are of course reusable. 

Note.  An adults eye is about 25 mm in diameter, or about 1". Infants eyes are about 18 mm in diameter.

 

Body  'Enhancements'.

I sometimes wonder about the ethics of 'improving' defects such as stretch marks, operation scars, wrinkles and crinkles, warts, pimples and cellulite !.  

 

Other mould materials

There are hundreds of kinds of mould materials available and here I can only give you a few general details. It should be enough to give you a 'feel' for the subject. 

Alginate.

A  safe, non toxic semi-flexible mould material.  An extract of seaweed. Comes in powder form to be mixed with water. Available in at least two setting speeds. Slow set ... mix time  1 minute, setting time 4 minutes. Fast set ... mixing time 1 minute, setting time 2 minutes. Being organic material it 'goes off' after a few days and also shrinks as it dries out, but is ideal for 'one off' moulds required immediately.  Commonly used for making replicas of infants feet and hands. Can be used on the face, providing the nostrils are left clear. Also used to replicate intimate parts of the adult body. If air bubbles or water runnels are a problem, first question the mix, then consider the construction of a simple vibration 'table' to stand the alginate container on. 

Latex rubber.

Natural rubber from the rubber tree. In it's natural state it is a white free pouring liquid, that air dries to a translucent golden rubber. Cured latex is very strong and capable of up to about 400% elongation.  Several coatings are required to build up mould thickness. This is time consuming and tends to rule it out for direct use on the model. Latex pigments are available to colour alternative coatings, this helps ensure an even mould thickness.  Thixotropic 'thickener' can be added to the latex to turn it into a 'paste' for spread on application.  It does  speed up mould production but still cures in hours rather than minutes. Can be used for making a mould from a casting. Latex shrinks about 5% as it air cures.  Latex can also be 'slush moulded'. Ideal low cost solution for hard wearing open or glove moulds

Polyurethane rubber.

Comes as a two part liquid mix.  Normally requires de-gassing in a vacuum chamber before use,  but in practice, so long as you do not produce a vortex when mixing and pre-coat the mould before pouring you can produce air free castings. Comes in various grades, but typically cures in hours and this precludes it's use directly on a model. 

Silicone rubber.

Again a two part liquid mix with a working time of up to about two hours. For best results it should be degassed in a vacuum chamber before use.  Generally cures in hours, but some fast curing silicones such as "Dragon Skin" can be de-moulded in 75 minutes. Silicone rubber is extremely tough, stretchable and hard wearing. Grades are available that can be used at temperatures up to 250 degree's C, which allows pewter and white metal to be cast in them.  Silicone rubber is the natural choice for production moulds for most materials. 

Note. Normally we expect a mould that is continually stretched to deform in the direction of the stretch.  I have had cases where stretching has caused silicone rubber to 'shrink' and deform in the opposite direction. The suppliers had no idea why this should have happened. The casting medium was concrete. 

Vinyl hot melt mould rubber. 

Comes in solid slabs which have to be cut up and melted at about 170 degree's C.   Overheating causes the rubber to decompose and it gives off nasty fumes.  Usually melted in thermostatically controlled double skin boilers. Masters must be non-porous or sealed with G4 polyurethane varnish, otherwise the heat will drive out air from the master and form bubbles on the working face of the mould.  I do not think it has any application in life casting and is best avoided.. 

Polysulfide rubber.

A two part liquid rubber, that can be used for 'smooth on' applications.  Commonly used for casting wax  cores for 'lost wax' bronze casting.  No real application for life casting.

Glass reinforced polyester resin (GRP)

Polyester resin comes as a two part liquid mix., the resin and a catalyst. Extreme care must be taken with the catalyst, which is normally MEKP (methyl ethyl ketone peroxide) as this can cause severe chemical burns.  Setting time depends upon temperature and the amount of catalyst used, but is typically 30 minutes. Glass fibres in the form of chopped strand mat or glass cloth are used to reinforce the casting. Cured GRP is very strong and makes ideal supporting cases for rubber moulds. It is possible to make a mould using it, but the smallest undercut on the master will prevent the removal of the casting from the mould.  For cheap flat open moulds a latex liner in a GRP case is hard to beat. 

Warning.  GRP cannot be applied directly to the skin because of the danger of chemical burns. Also as the resin sets it generates considerable heat. If too much catalyst is used, the heat generated can be high enough to cause self combustion.  

 

Casting materials

Although plaster bandage laminate is normally used to make castings, many other materials are also suitable. For example if a really lightweight casting is required it could be cast in polyurethane foam from a two part mix.  Paper mache is another material, which is often dismissed because of the drying time but can be made to set in less than 10  minutes, giving a porcelain finish. One day someone is going to find a way of spraying this onto the inside of a mould, or directly onto the model, to make cheap, instant castings .... that will completely change the way life casting is done. 

Spray on polyurethane plastic is already available to to make castings or spray on mould cases, but so far the cost of this two part material has precluded it's use for life castings.  Polyurethane makes a good substrata for various kinds of specialist finishes such as paint and Vapour metal spraying metallic finishes. It can also be electro-plated. I always find it comical that to produce a good polished brass look ... the cheapest way is to use pure gold !.

Note.  The vacuum forming page has further information on metallic finishes for plaster casts.

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Relevant postings by Magic ..........

"Metal Powders"

"Most metals are available in powder form. The most common ones are
those used in polyester gel coats in GRP work. In UK, South Western
Plasters stock the following metallic powders, Bronze, copper, Antique
Black, Brass, aluminum, Iron and graphite powder. For best effects it
should be used with at least 50% powder to 50% clear resin. To ensure a
thorough mix, catalyst (MEKP) should be added to the resin and mixed
before the metal powder is added, thickening the mix. It is then
applied by brush to the surface to be treated. At 12 degrees C, pot
time is typically 25 - 30 minutes. The trick is to paint it on with a
reasonable thickness (about 0.5mm - 1.0mm ) and then stop playing with
it !. This allows the resin to smooth out, without brush marks.

Leave the resin to set until the surface is no longer tacky. With 220
or finer grit on a block, remove any obvious runs. Then 'cut back' the
surface with wire wool. This reveals the metal. As soon as the metal
is exposed it will react to the atmosphere as metal does. So as soon
as you have the finish you want, polish the surface with mould wax to
seal it.

Aluminum powder mix looks like polished steel when burnished. Bronze,
brass and copper powder mix will patinate, using the usual chemicals.
Iron powder mix will actually rust !.

I think one would have to experiment when coating plaster, as it
obviously has to be sealed. For anyone abroad, you should be able to
buy aluminum powder from any auto body shop, where it is sold as a
filler.

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"Runnels, mix separation and air bubbles ........"

It does not really matter what casting medium you are working in,
defects tend to happen. Entrained air is the greatest problem due to
introduction of air during the mixing process. Most air is induced
when the mixer has produced a vortex, so the obvious answer is to slow
down the speed of the mixer paddle to avoid a vortex. Some air will
always be introduced into the mix, and the solution is to make sure it
never appears on the surface of the mould. To make this happen it has
to be forcibly displaced in an upwards direction, away from the mould
surface. When making silicone and polyurethane rubber moulds, we
de-gas the rubber mix in a vacuum chamber before use.
If we consider the case where an alginate mould is being made
of a union of hands, one may have control of the movement of an adults
hand, but not that of an infant. To expel the air from the mould, the
universal solution is ... vibration. Vibration expels air, fills
voids and strengthen the casting by consolidating it.
Vibration is caused by a displaced mass, so a simple motor with
an off-set weight on the output shaft will generate as much vibration
as you can handle !.
For the hands runnel problem, first I suggest one questions the
mix and then I simply recommend that the mould container sits on a
simple vibration table.

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