NeoprenePart 2 – Making the Neoprene Mask
OK - now that we’ve had loads of fun and fulfillment getting creative with the clay, it’s time to get to work and make a mask that is wearable and durable. Not that what follows isn't fun - it just demands a little more patience and thoroughness. (A little music always helps.)
The masks are made out of neoprene, an industrial latex compound that cures to a slightly flexible state. The mask holds its form like a leather mask and is equivalent in weight. The advantage to a neoprene mask is that it is an affordable way of achieving an incredibly durable and professional product. And multiple masks can be made from the same mold. Because of their durability, neoprene masks are ideal for classroom use and touring
The casting frame, made of packaging foam and the duct tape left over from protecting your house against terror attacks.
In casting anything with plaster you need something to retain the liquid plaster in as it hardens. Since we decided to use a 3-dimensional mannequin as a sculpting form, we now face the challenge of how to cast a plaster mold with it. We could cut the back side half off with a saw and cast the mask on a workbench using clay for retaining walls, but then we just wasted a perfectly good mannequin. My solution is to construct a casting frame out of packaging foam and duct tape. (The foam is used to pack large appliances and usually disgarded in the garbage dump in back of department stores.) Both repel water and plaster so they make a perfect form. After taping together enough pieces of foam for the depth you need, cut out a hole that has the dimensions of your mannequin to fit in. Then construct your 2” retaining wall with leftover pieces. Seal all the seams with good old duct tape.
Sealing the seams.
Plug the undercuts.
Apply the release agent.
SEALING THE SEAMS
Place your sculpture into the frame and seal all seams and undercuts around the piece with leftover clay.
PLUG THE UNDERCUTS
Plug undercuts on your sculpture with clay. Especially eye and nose holes, which will be cut out of the finished mask anyway.A deep hole in a positive sculpture will create a tall and unstable column in the negative mold. These will tend to break off as you remove the mask from the mold.
APPLY RELEASE AGENT
Apply a release agent of liquid dish soap over the whole clay sculpture AND frame. with a small brush. Be sure to get into crevices and lines. DO NOT use petroleum jelly as a release agent for making a neoprene mask. It only clogs up the absorbent qualities of the plaster and makes the mold almost unusable.
Sift the Plaster into the bucket one handful at a time.
Mixing the plaster with a mixing bit on an electric drill.
Most hardware store plasters will work for creating a mold but I find it's best to find a construction supply house and buy your plaster there. For one, the price is about 1⁄2 of what you'll pay at a hardware store and two, the plaster is much better. For casting a neoprene mask the best plaster is #1 Pottery Plaster, which is designed for slip casting.
The old tried and true method for mixing plaster is to start with the water and add the plaster to it a little at a time. Measure the amount of water in bucket or large container. Figure in that however much water you have, the final plaster mix will be 1/3 again that amount. So if you have 2/3 gallon of water, you'll end up with approximately 1 gallon of plaster.
Sift the plaster into the water one handful at a time. Do not stir at this point. After many handfuls the water will start to get supersaturated with plaster and no longer absorb it. An island will form at the surface with little damp cracks of wet plaster. This is good. Time to stop adding plaster. Let the mixture steep for about 5 minutes, intermingling and getting acquainted. (During this time is when I usually apply the release agent to the sculpture.)
When 5 minutes is up mix the plaster thoroughly. Undermixed plaster is not very strong. I use a mixing bit with an electric drill but a vigorous stir with a paint stick is fine. The mixture should be pourable, about the consistency of pancake batter. But it won't be poured since our retaining wall is only 2 inches high. We'll ladle it on slowly. This is where the patience comes in.
Applying the detail coat.
Pouring the mold.
APPLYING THE DETAIL COAT
Carefully apply a detail coat of the freshly mixed liquid plaster onto the surfaces of your mask. Use a small brush to very lightly release any trapped air bubbles from deep impressions and crevices. An air bubble will translate into a wart-like bump on the surface of the finished mask. (Which can be easily removed also.)
POURING THE MOLD
As the plaster starts to thicken keep ladling it directly over the detail coat. It will take time for the plaster to harden enough to build up the mold. If you used room temperature water the process will take approximately 20 minutes. (A bit faster for warmer water.)
Soon the plaster will start to really thicken and stay put. Make sure the walls of the mold are uniform in thickness. There is a tendency for the top of the mold (which will soon be the bottom.) to be the thinnest. Scoop plaster from the sides to thicken this area.
Shaping the mold.
SHAPING THE MOLD
Soon, very soon, the plaster will become so firm that it is no longer workable. Create a level flat spot, or plateau, on top. This will become the bottom of the mold and the more level it is the better it will hold the Neoprene Latex liquid.
It will take about 20-30 minutes for the plaster to cure. This is a great time to clean up your tools and bucket. (And yourself. Wash your arms first. Plaster is a bear at removing arm hair.)
The plaster will get warm as it hardens. This is especially helpful when removing the clay from the mold. Monitor the casting with your hands. You’ll feel how hot it actually gets. After about 30 minutes it will start to cool a bit and this is the perfect to remove the clay from the mold.
Removing the frame from the mold.
Freeing the mannequin from the mold.
Removing the mannequin.
Peeling the clay away from the plaster.
REMOVING THE CLAY
Flip the whole contraption over and remove the frame from the mold. The outer edges of the mold can be very sharp. It’s a good idea to dull them by scraping a putty knife or chisel across the edge.
Next thing is to free the mannequin from the clay. Grab the neck and work it back and forth to see if it will loosen. Sometimes it will come right out with little effort. Most of the time, however, you will need to remove a little clay from the sides with a wire sculpting tool before you get any play in the mannequin.
Once the mannequin is gone you can start to remove the still warm clay. It should easily peel away with little or no sticking if you applied enough release agent. For some small undercuts you might have to use a small wire tool to assist. Store the clay away for your next project.
Gently wipe any clay or soap residue from the insides of the mold with a warm slightly damp cloth.The plaster mold needs to dry out thoroughly before you can pour Neoprene latex into it, usually 1-2 days is optimal, but using an electric fan can speed up the time to overnight.
POURING THE NEOPRENE CASTING
Neoprene rubber latex is a more rigid and durable cousin of regular latex rubber. It is very easy to use and will enable the mask-maker to easily make multiple copies of a mask from the same mold. Neoprene rubber latex is not a dangerous product to use but some simple precautions are always wise to follow. Ventilation, goggles and rubber gloves are recommended by the manufacturer.
To make a mask using Neoprene latex, you use the age old pottery process called slip casting or absorption casting, where the liquid latex is poured into the a clean DRY plaster mold and allowed to sit for awhile. This plaster mold absorbs the solvent from the liquid leaving behind a skin or thin wall, which clings to the side walls of the mold. Allow it to set in the mold approximately 1 to 3 hours for desired build-up. The liquid level may drop due to absorption. This is normal, just top it off with additional casting compound if necessary. 2 hours will produce a wall thickness of approximately 3/16". (Cured Neoprene is very tough and durable and it is unlikely that you would want a wall thicker than 3/16".)
The bulk of the liquid is poured back into its container to be reused again. Allow the neoprene latex skin to cure approximately 8-14 hours. (A small fan will again speed up the process.)
REMOVING THE MASK FROM THE MOLD
When the neoprene has set but not hardened carefully peel the mask away from the mold.
The mask is drying, but still soft - It retains the whitish color of the wet neoprene.
Here is the mask after the neoprene has dried. Notice that the color has darkened.
As the leftover skin dries it turns beige and shrinks a little, allowing the latex mask to be removed quite easily. Slowly peel back an edge and work the skin off gently. In this state the mask is very flexible, much like a regular latex Halloween mask. You can trim away the edges with a scissors and prop up the mask in the shape you want to let it cure and harden for 1-2 days. Then it is ready to receive the finishing work. The mask still contains some solvent at this point and there is a noticeable odor which will disappear in few days once the neoprene is fully cured.
Trimming the mask.
TRIMMING THE MASK
Once fully cured the mask is firm like Tupperware. At this point you can cut out the eye and nose holes with a mat knife. (And be careful there.) Or if you have a Dremel tool, drill them out. A Dremel tool with a wire brush attachment also works great to smooth any rough edge or large blemishes that might have formed from a bubble in the casting of the mold.
Attaching the strap.
Removing the sharp edges.
Painting the mask.
You can create a smooth skinlike surface and remove any other small blemishes with a rag dipped in acetone.
ATTACHING THE STRAP
Attach an elastic strap to the mask with hot glue or epoxy. As a guide the best placing for the strap is level with the top of the eye socket.
REMOVING THE SHARP EDGES
The mask is almost ready, but remember - it's going to be worn. Be sure to sand off the edges where the mask has been trimmed so it is comfortable to wear.
PAINTING THE MASK
All types of paint adhere well to neoprene, lacquer, enamel, and acrylic. I like the ease and clean-up of acrylic so I always apply a coat of gesso to the mask as an undercoat primer for painting.