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When starting out, there are many different materials in which to sculpt from.(water baste clay, oil clay or plasticene, castilene, and wax.) Use which best fits the occasion, or what is affordable.
Each material has pros and cons. Water clay is cheap and fast to work with but dries and will normally need an armature. plasticene is commonly used. this oil clay will never dry and comes in different harnesses, but is easily damaged and will need an armature. Wax is the cheapest, especially when only making one bronze. wax can go directly to bronze which cuts out a lot of work but can be disastrous because you only get on chance. Then there is castilene. Castilene is a modeling compound usually used in the toy industry. It is expensive and can be hard to get, but it comes in three harnesses doesn’t need an armature and for those who work in wax, can be burned out.
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The second step after creating your sculpture, is making a way to reproduce your creation easily. We do this by making a mold. (Plaster, latex, or silicone) are your material choices and again which one you use depends on what you are making and ones price range. I am going to talk about a silicone or “rubber” mold.
A rubber mold is expensive, but is durable and pliable. It will accept several different kinds of materials for the finished product. Example: Resin, wax, plaster, clay, etc. This makes silicone the best for most of what I do.
Before you pour the mold you first need to make a shim line. This is where the two half’s of the mold will separate. then you pour your mold. (tip. keep the mold thin buy pouring in two layers with a piece of cheese cloth in between for strength). When both half’s are complete a “mother mold” needs to be made. The mother mold is a plaster mold on the out side of your rubbers one, designed the cradle the form of the rubber in order to keep it from bending or getting deformed, while pouring a cast “copy” of your sculpture. Now the original can be removed to reveal a negative of you design.
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After you have made the mold and poured your wax, you are half way there. Now you must fix any problems you have with the wax. If changes need to be made do them now. You may need to put pieces together if for instance you made a human figure, and the arms had to be separated when made the mold. Wax is much easier to work with than bronze, even if you want a polished look in the bronze, the wax can be polished and smoothed now with some lacquer thinner and a rag.
With that done, you move to the next stage, gating. Wax rods and a pour cup, are now attached to your piece. these will later act as gateways for the bronze to flow in the investment and air to escape. Venting rods are to be placed any place in which air can be caught and restrict the metals flow.
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This next few steps are the most stressful. When you think you have all your gating and venting done, weigh the entire thing on a small scale. This is so you can figure out how much metal is going to be needed. This is were your high school math comes in. Wax to bronze is about 10 to 1. So for every 1 lb. wax, you need 10 lbs. bronze. Now make a note of the weight, for when you continue, you can’t go back. Before face coating you should get ready for the investment by make a cage. The cage, made of chicken wire and tar paper, acts like a wall, containing the investment. (Tip: make sure there is at least 3 to 4 inches of space on each side and on the top)
Time to face coat. Face coat is used to give you a strong and detailed shell around your sculpture. Make sure the face coat is 3/4 in. thick all around, this may take a few coats. After the face coat has set, place the sculpture in the cage and start adding your investment. when you reach the top attach one more piece if chicken wire to the top add make sure it’s submerged. The investment should be mixed in parts, if you make to much at once the investment will flow out the bottom. As soon as that sets up, remove the tar paper and load the invested piece into a kiln. Make sure you pour cup and air vents can be seen on and are facing down. In the kiln the wax will be completely burnt out leaving a hollow cavity in its place. This will take almost a week. Time to sit back relax and cross your fingers that nothing goes wrong. If you worked entirely from wax or Castilian with no mold, this week will decide weather you wasted hours, days, weeks, months. Make a mold!
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A week has past, and the wax is gone, hence “lost wax method” time to pour. Your investment should now be placed in some sort of encasement (wooden box) pour hole up, then impact the area between investment and box with sand. This will contain any molten bronze in the case of a blowout. When the bronze reaches temperature and the investment is just right the metal is poured. Caution: This should only be done by experienced professionals.
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Now that the bronze has cooled enough to handle it’s time to break it out of the investment. Take the whole thing over to a disposal unit, (dumpster) and with a hammer, wire clippers, a wire brush, and a hose, start removing the investment. (Be sure to be wearing safety goggles, gloves and a face mask) ( tip: Removing the investment will its still hot will make the job easier but can be dangerous. Use Caution.)
All most done. With the bronze clean of face coat, it’s time to remove all the now bronze gating. For this you can use an angle grinder for the big stuff or a saw. As you get closer to the sculpture switch to smaller tools. A dremmel tool is nice but can be expensive, and if you are not careful can do more damage then good. To be safe, some files, a hammer and chisels will do less damage if a mistake is made. Take your time, read up on metal work techniques and after elbow grease and sweat you are done. Assuming there is no problems with the metal pour.
Optional: Apply a Patina to your bronze. Bronze will naturally change color over time from it’s environment. A patina and sealant will force a color of choice.
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