In casting, the metal to be used in making the jewelry is melted and shaped using a mold.
This is a basic method practiced by jewelers in shaping, in one form or another, almost all of the known metals. The operation of casting is used in mass production, and it is commonly applied when making a copy of a jewelry design.
There are Four Basic Steps to be Followed in Casting Jewelry Metal:
- Preparing the rubber mold.
- Making the wax pattern.
- Preparing the mold which is made of investment satin cast.
- Shaping or forming the metal to be used in making the jewelry.
Casting requires the use of special tools and materials, such as a wax model. Professional casters can be asked to make wax models for your use.
Materials and Tools:
- special rubber for making the rubber mold
- rubber mold frame
- vulcanizing plates
- melted casting wax
- investment satin cast
- casting flask
- sprue base
- centrifugal machine
- compressor and gas tank
- surgical knife
A. Preparing the Rubber Mold
The outcome of the shape of the metal will depend on the mold to be used, that is why, this is done very carefully. Remember that the copies of the design as molded, come out smaller than the original jewelry or model due to metal shrinkage during cooling. But the copies made with the help of the mold will certainly be of the same sizes.
- Cut the special rubber into a square.
- Place the jewelry design to be copied in the rubber mold frame. Press the model or . design against the rubber. (The rubber mold should be tightly packed into the frame to get the accurate shape of the design).
- Heat the rubber square in the vulcanizing plate for about seven minutes. (The length of heating time will depend on the thickness of the rubber).
- Remove the rubber from the frame and make a slit in the middle to make the wax pattern. Noticed that the jewelry model is actually impressed inside the mold. (Each mold is used for only one piece of jewelry).
B. Making the Wax Pattern
A syringe filled with melted casting wax will be used to make the wax pattern.
- Put wax into the rubber mold and let it solidify.
- Once the wax has solidified, remove it from the mold. The hardened wax will serve as the pattern for the next mold to be made. Several wax patterns can be made equivalent to the required number of pieces of jewelry to be made.
C. Preparing the Mold Made of Investment Satin Cast
The investment satin cast mold forms the metal to be made into jewelry. Tools and materials such as casting flask, sprue base and investment satin cast are needed. The first two are made of steel while the investment satin cast is in powder form (like to the plaster of Paris).
- Attach the wax pattern into the sprue base. Then put the pattern inside the casting flask.
- Mix enough water to the investment satin to arrive at a powder consistency similar to that of the plaster of Paris.
- Let the investment satin cast solidify for about 1 1/2 hours.
- Meantime, heat the flask on a casting oven or over live coal to melt the wax inside. Heat for two hours.
- Take the flask away from the heat using a pair of tongs. The flask will serve as the mold for the metal.
D. Shaping or Framing the Metal for Making the Jewelry
- Put the casting flask inside the centrifugal machine. Attach the flask to the crucible (which is made of steel) where the metal will be melted.
- To melt the metal, use a blow torch with its fire directly pointed at the metal.
- Once the metal is melted, rotate the centrifugal machine. While rotating, notice that the melted metal flows into the casting flask. All the spaces inside the casting flask must be filled with the melted metal. Allow a few minutes for the metal to solidify before removing the casting flask from the machine.
- Take the casting flask off the centrifugal machine once the metal has solidified and hardened.
- Submerge the flask under water to remove the investment satin cast. Notice that the cast metal is now coated with the solidified satin cast.
- Clean and polish the cast metal, which is now transformed into a piece of jewelry.
source: TRC Business Guide, www.trc.dost. gov.ph, photo from www.freedigitalphotos.net