Thursday, November 12, 2009

Hand Casts & Clay Sculpting

For our most recent class we worked on hand casts and clay sculpting. This was a continued lesson of our life casting and introduced the beginning process of designing our own prosthetics.

To begin:
1) Prepare your model. Wipe excess dirt and grime with a baby wipe. Apply moisturizer beforehand if they have sensitive skin that is susceptible to drying out.
2) Mix up your algaenate and pour.
3) Create your Mother Mold with Plaster Bandages.
4) Time for Pour Up. This is used with Ultracal 30 same as our previous Life Cast.
5) Set up Palette for Sculpting.

The step you don't see pictured before this is the mixing and application of our Algaenate. This is poured over the hand and smoothed on. Use gloves as it tends to get messy. You can also apply with Popsicle sticks or whatever's handy.

The algaenate should be the consistency of honey. The more water you add to your mix, the less time it will take to cure, meaning the less time you have to work with it. Since it will be runny, reapply any excess by applying back onto the hand. As it dries add texture by touching the outside of it with your fingers or stick or whatever. This texture will help the plaster strips grip to the algaenate in the following steps. A fingernail scratch test will let you know when the material is set and ready for the next step.

Once the Algaenate is dry, take about eight 12 inch strips of plaster bandages and dip them in water. Warmer water will cause the gypsum to activate faster speeding along the process. Make sure the water is wrung out thoroughly as you apply the bandages. This creates the mother-mold to your softer algaenate mold.

Apply the strips roughly to the wrist, overlapping any application of algaenate. Your plaster mold should envelope your original casting. For a hand you'll use about half a roll of plaster bandages. When doing say a head, you'll use about 8-12.

Once the plaster is dry, flip the hand. Exercise caution as you don't want the two molds to separate quite yet.

You can have your model wiggle their way free, but be prepared to cut them out if necessary. Though this is basically chemistry, it's not an exact science. That's what makes it so damn fun!

Once free and clear of your model, you now have a mold of their hand. Algaenate has a tendency to shrink, so for the best results an immediate casting is necessary.

Prep your mold on a workable palette. Save yourself time and headache by having the materials needed for casting ready before this step. Now the area near the wrist is now like an open drain. To prevent any leakage of Ultracal 30, plug it with a damp paper towel. This will keep your work station from resembling a dirty puddle.

As you saw from the initial pull of the mold, some of the fingers were connected by the casting. You can "chase" or remove them with a pair of cuticle scissors. By doing so this opens the mold for a proper pouring.

Once the wrist area is secure you're ready to pour your Ultracal 30. A steady even pour will ensure maximum results.

A thicker mix pour at low height helps combat the air bubbles that naturally tend to form from mixing your materials. Be sure that you don't overfill, this wastes our material and turns into a messy clean-up.

Carl floated more Ultracal 30 into the mold, making sure it got into the crevices from the fingers.

Take caution with your fingers as they have a tendency to break. When the casting material is still wet you can add small strips of wires as fortification. Cut your wire to fit and push into the fingers. Make sure there is room to cover them with additional plaster. Be sure you're doing this before the plaster starts to kick. You don't want to start digging wires into your mold as the material begins to set, leaving you with a hand casting that is unusable.

From this we pulled an almost exact double of our model's hand. It's important to remember the plot of MULTIPLICITY here. You're making a copy and from this copies of copies. Your best results will come from your very first pours. Consider it a generation of degradation.

Now on to sculpting. We used a simple 4 grade oil based clay. This can be found in any art supply story. The heat from rolling it in your hands makes the clay more pliable and easier to work with. Baby wipes take off any residue, so don't wipe it on your clothes since it can stain. You really only need a small amount. Notice the pen in this picture for scale.

We began our build-ups on ready made hands. You ultimately want your sculpture to be as thin as possible. Thicker prosthetics are fine for other parts of the body, but the hand is a place of maximum flexibility. You want to deliver a piece that will not inhibit movement. Thin is also important because when the piece is applied the edges are going to be the dead give away seen on camera, ruining the illusion. Clean edges are easier to cast and to apply.

The Steps are:
1) Rough out your clay and begin your pattern.
2) Smooth out your edges.
3) Feather your edges. Smooth. Repeat and repeat. Feathering consists of smoothing the clay to its thinnest possible consistency and removing the excess from the edges of your piece.
4) Create your wound. Take your time, this is the most important step. These are the same fundamentals as working with wax.
5) Texture. Stipple if needed, add depth. This will add believability when viewed on camera.
6) Wash. This is meant to remove fingerprints and smooth any imperfections. This is done with denatured alcohol. Use caution with this as it's a known irritant.

Most of the class opted for continuing our previous lessons, sculpting bigger scars and gashes. One sculpted cat scratches while another student worked on boils and blisters. I was inspired by AN AMERICAN WEREWOLF IN LONDON and began a sculpting of a pentagram. This is an iconic image seen in countless Hammer Horror films and other scary stories of evil and damnation.

My idea was to cast a prosthetic that could yield to looks upon application and painting; a singed branding or a lacerated cut. It's important to remember when creating your sculptured wound what caused the injury in the first place. This will help with size, placement, and the overall direction of the piece.

I used a quarter-inch sculpting loop to smooth away the excess areas of clay and a Popsicle stick to edge out the lines of the design. I did stumble upon one huge problem when I thought I was complete. The design I sculpted went clean through to the casted base model. This meant that each individual piece would come out as a casting versus one solid piece. Not to worry, it's only clay. I smoothed out the piece, added more clay and started over.

I realized that to be able to cast a one piece prosthetic that I needed to build up a thicker layer of clay and only sculpt to a layer that still had a thinner build-up of clay underneath it. Basically cutting into it without cutting through it. This would guarantee a one piece prosthetic yielded from the casting versus the 11 small pieces I would have had from the previous sculpting. I also had to continue past the casting area to give the piece an edge for adhension when applied as a prosthetic. The previous sculpting would have basically given me a patch like a sticker, when I really need the farther edges for blending with make-up later on.

Next week I will add a build-up of clay around the base of the hand, separated by a small reservoir. This additional clay build-up is designed to save in the amount of material used to cast the piece, meaning it will be just the piece I sculpted and not the entire hand that I sculpted it on as a base. I am very eager to cast it, but more excited to see it applied. Hopefully both instances (burn and cut) that is was designed for will produce the results I'm looking for.

1 comment:

  1. Can't wait to see what happens with this next week.