To cast jewelry, create a mold, run it through a burnout cycle in a kiln, melt metal, pour it into the mold, and quench it in cold water. To finish the jewelry piece, remove it from the mold, file away the rough edges, and polish it.
- Select the model
Select the jewelry item you want to cast, and inspect it for any defects. If necessary, repair the model.
- Attach the sprue to the mold
Weigh the rubber sprue bases, and mark accordingly. Melt the wax where the sprue wax and base meet using an alcohol lamp. Use both sticky and designer wax to attach the sprue to the mold, which creates the passage through which you pour the metal.
- Mount a sprue on the model
Select an out of the way spot for the sprue. Place wax where the sprue meets the model to secure it.
- Mount the model on the tree
Place a fillet of wax at the connection point for the model sprue and the tree. Warm the wax with the lamp, and use it to attach the model to the tree.
- Assemble the base
Put the flask and base together, and check to ensure you have three-eighths of an inch clearance between the model and the wall of the flask.
- Weigh the sprued base
Remove the flask. Weight the sprued base, subtracting the weight of the sprue itself from that measurement. To determine the amount of metal needed, use the following formula: (grams of wax) x 1 x (the specific gravity of the metal to be used).
- Mix the investment
Assemble the flask and base again. Following the manufacturer's instructions, pour water in a rubber bowl, and add the investment powder. Keep adding the powder and mixing until it is the consistency of cake batter.
- Vacuum out the air bubbles
Use a vibrating platform to finish mixing the investment. Place a bell jar over the bowl, and switch on the vacuum. Leave the vacuum on for 1.5 minutes.
- Set the investment
Pour the investment into the flask while keeping it tilted. Repeat the vacuuming procedure for the flask. Allow the investment to set.
- Finish the mold
Use a twisting motion to remove the rubber sprue. Place the mold in a kiln, and run the burnout cycle.
- Melt the metal
Warm up a crucible. Place the flask in a centrifugal machine, and place the crucible next to it. Warm the metal until it melts.
- Pour the melted metal
Use a stirring rod to stir the metal and remove any impurities. While the mold is spinning in the centrifugal machine, slowly pour the metal into the mold. Wait until the mold cools to dull red, and then quench it in a bucket of cold water.
- Finish the jewelry piece
Slosh the mold in the water to remove the castings. Clean the investment from the jewelry piece. File off any rough edges, and polish.