Chapter 3:
Go With The Flow:

1. Materials and Safety
2. Terms & Measurements
3. The Physics of Fluids
4. Basic LifeCastâ„¢ Design
5. BODY PARTSâ„¢ Videos

Fluid behavior in lifecasting.

The techniques of lifecasting are primarily governed by the scientific principals of fluid behavior.
Fluid: Anything that flows into the shape of the container that holds it is called a fluid.

Technically this includes liquids and gasses but, fine powders could also be considered "fluid" since they also conform to their container's shape. Fluids have certain characteristic behaviors which are important to a lifecast sculptor.

Thickness, Viscosity And Flow:

The thickness of a fluid is also called viscosity.

With BODY PARTSâ„¢ kit mediums the more powder that is used in relation to the water (see ratios in Chapter 2), the higher the viscosity of the resulting fluid.

• High Viscosity (paste) will not allow fluids to flow as quickly around or into the shape of your artifact. But, they also don't run off as easily so you can spread these fluids as a paste onto someone's face or torso for example or into the mold to create hollow "slush" castings which are much lighter than solid ones.
• Medium Viscosity (batter) is the one used for the basic project. It is ideal for "dipping" methods where you put your hands or feet into a container of the fluid and pour the casting into the resulting mold.

Thickness, Viscosity And Flow:

• Low Viscosity (creamy) fluids are somewhat weak but easy to pour and economical. They are ideal for shallow "relief" sculptures which are not completely 3 dimensional.You must be extra careful to avoid bubbles with thin fluids like these and mix the powders extremely well, meaning you should use very cold water to extend the working time as much as possible. Then let it sit for 30 seconds to a minute so the bubbles can float up before dunking into it.

Mixing Liquids With Powders:

It is important to estimating the materials a project will need that you understand what happens when they are mixed with water and why. That, in turn requires an explanation of a powder's composition.

The ArtFormâ„¢ contains a large percentage of "diatomaceous earth". Diatoms are tiny, ancient creatures which leave behind extremely complex shells or skeletons when they die. These shells are almost completely empty but so complex that a single pound of diatomaceous earth has the surface area of a football field!

Because the water fills these empty spaces the overall volume of the ArtFormâ„¢ plus water is practically no different from the volume of the water alone. So when you estimate the amount of ArtFormâ„¢ needed it should be based upon the volume of water alone needed to cover your design.

ArtFormâ„¢ Molding Compound
• A thick ratio for ArtForm™ is 1:1 (equal water and powder by volume)
• A medium viscosity ratio for ArtForm™ is 2:1 (2 parts water to 1 part powder by volume)
• A thin ratio for the ArtForm™ is 3:1 (3 parts water to one part powder by volume).

The ArtCastâ„¢, on the other hand is almost entirely composed of 'solid' particles of calcium sulfate which do not absorb water but partially dissolve in it. Because of this important difference the resulting mixture with water is exactly opposite to that of the ArtFormâ„¢ described above. ArtCastâ„¢ adds to the volume of the water.

This additive process can be considered a kind of "displacement" similar to placing an egg, for example in a cup of water which makes the water level rise. So when estimating the amount of ArtCastâ„¢ needed it should be based on how much powder is needed to fiil the mold with the amount of water as your secondary consideration.

Refer to the illustrations at the right for a more visual explanation.

ArtCastâ„¢ Statuary Cement
• A thick ratio for ArtCast™ cement is 1:3 (one part water to 3 parts powder by volume)
• A medium viscosity ratio for ArtCast™ cement is 1:2 (one part water to 2 parts powder by volume)
• A thin ratio for ArtCast™ cement is 1:1 (equal parts water and powder by volume).

In our basic kit projects the thickness of the ArtFormâ„¢ will vary slightly depending on the models' hand size. Those with large hands or with multiple hands in the casting matrix package (see Chapter 2) all at once will use less water than projects with a single small hand.

Since the premeasured amount of ArtFormâ„¢ powder remains the same, some variation in working and setting time is to be expected in those BODY PARTSâ„¢ kits.
• As a beginner stick with the instructions, don't try anything too difficult at first and you should have no problems.

Notice that the viscosity of the ratios for these two materials are exactly opposite!

Note: Earthium(f/x)â„¢, PolyArtâ„¢ and other advanced media are beyond this Basic Concepts section. Please refer to their instructions or to the Advanced Methods section of this Library.

Gravity Casting:

This is by far the most common method of casting 3 dimensional objects. It is as ancient as art itself. It can only be done with medium and low viscosity fluids. Which is why they are used in your basic project.

Other ways are discussed in the Advanced Methods section.

Gravity Casting:

Gravity casting follows two natural laws:
1. Gravity only pulls straight down. This limits where your casting medium can go in the mold and what you must do to get it there.
2. Air only moves straight up. This determines where to expect air bubbles and air traps (explained below) and what you must do to avoid them.

Air Bubbles:

Air Bubbles are a major nuisance in lifecasting or any kind of mold making and casting craft. The proper techniques may not completely eliminate these little frustrations but, they will certainly minimize them. Bubbles can turn an otherwise quick and easy project into hours of tedious and meticulous repair or a complete re-do.

On Earth of course, we live in a huge bubble called the atmosphere which is slightly "greasy" and sticks to everything. The little bubbles which annoy a lifecaster are mixed into the mediums from that big one that surrounds and supports us.

Air Bubbles:

Air bubbles are a gas and behave like any other fluid. They cannot negotiate corners or obey your desires. You cannot command them, only trick them with your craftiness.

If you have access to a vacuum chamber, great! Use it. If not, a little skill and understanding usually solves the problem. Correct BlendBagâ„¢ (Chapter 2) use and the following information will allow a lifecast artist to minimize or eliminate most bubbles. The ones which do get through to your final sculpture can be easily repaired (see Chapter 4).

The 3 Sources of Air Bubbles:

1. Skin and Surface Bubbles: Ever dive under water and see thousands of bubbles hanging on for dear life? Notice how they especially love to gather around hair follicles? Even infants have millions of tiny, almost invisible hairs covering their entire bodies. Air bubbles will be trapped there.
• These will appear as bumps on the final casting similar to mold bubbles described below. To eliminate these bubbles you must have the model move around in the fluid for several seconds after submerging.

Air Bubbles:

This is part of what you will remember as Positioning Time, a portion of Work Time in Chapter 2.

You can also rub the fluid all over the body parts being copied, creating a thin coating and removing the bubbles before submerging. This all must be done within the Working Time.

2. Mold Bubbles: These are mixed into the ArtFormâ„¢. They also appear as bumps on the final casting. However the only mold bubbles that really matter are the ones on the "skin" of the mold, right? The ones we can see, that can affect our work. These can be controlled.
• Mold bubbles appear as bumps, identical to the Skin Bubbles described on the previous page. They are minimized by correct BlendBag™ or wire whisk mixing.

Remember, bubbles only go straight up from the bottom. Once they have all floated to the top, that's it, there are no more. After squeezing the fluid ArtFormâ„¢ into your container, jiggle it so the bubbles float to the top where they will pop before submerging.

Earthium(f/x)â„¢ use as described in Advanced Methods can eliminate virtually all mold bubbles.

This will take a little time and is only effective during the Working Time, before the ArtFormâ„¢ begins to set.

Another approach is to keep the model moving around in the fluid ArtFormâ„¢ until it begins to set. When it gets too thick for the bubbles to move any more, the model then holds still.

Mold bubbles can usually be popped off very easily right after unveiling the LifeCastâ„¢, while the cement is still soft.

3. Interior Cast Bubbles. These are mixed into the ArtCastâ„¢ and are actually surrounding each particle of the cement powder to begin with. That's why, if you sift the cement powder into a bucket of water a riot of bubbles appear on the surface.
• Cast Bubbles appear as holes in the sculpture. But, like an iceberg the largest part of a cast bubble is below the surface as the illustration shows.

Again, the only ones we care about are on the surface between the skin and the mold, where they will show. Once all the bubbles from the bottom have floated up there are no more. They float straight up until something stops them, usually a lateral or horizontal area inside of your mold.

Correct soaking and mixing procedure (Chapter 2) will get rid of most cast bubbles before you even pour the fluid into the mold. Make sure you tap and jiggle the mold thoroughly at each stage of the casting process (Gravity Casting above).

Cast bubbles can usually be filled easily with a drywall paste right after unveiling your LifeCastâ„¢, while the cement is still wet. Modern epoxy putties work very well after the LifeCastâ„¢ has dried completely.

The Air Trap:

Air Traps are very similar to bubbles in their causes but much more serious. Even a small air trap can be very difficult to repair on something as detailed as a lifecast of the human body where every fingerprint is duplicated.

Remember from Gravity Casting that air goes only straight up. If there are areas of your design that prevent it from escaping, like the fingertips in the illustration, then these areas (shown in blue) cannot be filled with cement. The air won't let the cement get in, nor can the air escape because the mold is covering it. In other words there will be some 'mysteriously' missing parts.

As the photograph shows, this will result in incomplete areas of the lifecast, the fingertips are missing. These are difficult to repair except by re-casting the missing areas and carefully carving the pieces to fit.

Air Trap:

How Air Traps Happen:

If any parts of your design are not straight up and down, like the bent fingers of the illustration, precautions must be taken to ensure a successful lifecast sculpture.

If you simply pour the cement straight in, the result will be similar to those in the photograph. It is usually much easier to simply start over but, the missing areas can be re-cast, shaped to fit and attached with epoxy.

Avoiding Air Traps:

One way of avoiding these traps is to make sure all parts of the lifecast are lower in the mold than the parts above it. For example, keeping the fingers fairly straight and bending the wrist back slightly as the illustration shows.

This is required in a beginner's BODY PARTSâ„¢ kit project to be covered by the Successful Creativity Guaranteeâ„¢ but can be very limiting.

Avoiding Air Traps:

Air Traps also frequently happen when holding objects to be captured in your LifeCastâ„¢ project. This is very important to make your model understand since you cannot see what they are actually doing once they are inside the mold. You can however practice with just positioning, observation and discussion with your model.

Tilt, Jiggle and Spin:

Since most hand type lifecasts will have an Air Trap or two its always best to follow the instructions exactly. To summarize that part of our BODY PARTSâ„¢ printed instructions:
1. Make your first pour of the ArtCastâ„¢ to only about half way up, but to at least the knuckle area of the palm.
2. Then tilt, rotate, tap and jiggle the matrix to get the fluid cement into all the nooks and crannies and let the bubbles escape.

Tilt, Jiggle and Spin:

3. Set the matrix upright and fill the remainder.
4. Finally tap the can with your knuckles firmly all around to remove any remaining bubbles.

This process will usually eliminate most common Air Traps.

Basic Air Paths:

Air Paths along with correct gravity casting can eliminate the dreaded air trap. They require planning and good communication with your model(s).

The top illustration shows one type of Air Path. If you have the model touch their fingers together as shown, then the air from the middle finger can escape through the thumb.

When the cement is poured it will fill the entire shape without encountering any air traps. This is also how partial or complete fists are made. The fingers must be tightly touching the palm.

Another type of Air Path is when two or more models are interacting to make a single, complex LifeCastâ„¢. These are some of the most interesting artifacts in lifeasting.

Basic Air Paths:

This is especially true when an older person and a younger one are involved, the wrinkled skin of age contrasting with that of youth.

In the 2nd illustration an Air Path is planned through the back of one person's hand. This allows the air to escape from the fingertips of the second model's hand.

There are a few more useful variations on the Air Path which are described in Chapter 1: "Dip & Dunk" of Advanced Methods. They are very important since many lifecasting projects are simply to large or otherwise not practical to manipulate in the manner described on these pages.

Suction & Air Pressure:

Since we live at the bottom of a huge air-ocean called the atmosphere, there are fairly large forces pressing down on us from all directions at all times. This air pressure tends to make semi-vacuums form when isolated pockets of matter are created, like inside of a mold.

In lifecasting, the mold fits the skin right down to the fingerprints and will hold you in. Because of this "vacuum seal", if you just forced your way out the mold would be damaged or destroyed. The inside and outside pressures must be equalized or joined.

To break this suction you must force air between the mold and the skin. We typically use air, blown in through the straw provided in all our BODY PARTSâ„¢ kits to release the suction. Water can also be used but, it makes the process messy and the water must then be poured back out immediately.

To release model from the mold follow these steps, doing one hand at a time:
1. First blow air with the straw firmly around the upper edges of where the wrist enters the mold to loosen it up.
2. Then slide the straw in the mold deeper. Be careful to press the straw against the skin as you do this so it doesn't scratch or gouge the mold.
3. Blow hard and the model should feel some areas of their hand loosen up.

Suction & Air

Repeat this in 2 or 3 locations around the wrist as the model wiggles gently. Be sure their fingertips are loose and have them slowly pull their hand free.

If any little pieces of the mold fall inside you can also use the straw to suck them out gently. Be careful not to inhale to strong or you could accidentally choke doing it this way.

You can also tip the can upside down and tap the pieces out before pouring the cast.

Mechanical or tank fed air compressors also work very well. especially in deep designs. However, make sure you have the regulator under control or you may damage your mold with too much pressure.

Go To Chapter 4: Basic Lifecast Design & Planning:
Good Luck Is When Opportunity Meets Preparation.

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