Casting jewelry is a process that involves casting a liquid metal alloy into a mold. This method is often called "lost wax", because the mold is created with wax which later melts and is eliminated to leave an empty chamber in the center of the mold. It is a technique that has been used for thousands of years and is still widely used by both professional and amateur artisans to make reproductions of original jewelry. If you want to make jewelry yourself using this method, follow the instructions described in the article.
Steps
Method 1 of 4: Model the Mold
Step 1. Carve a piece of synthetic wax to give it the shape you want
Start with something simple, as complex molds are difficult to hold together on first attempts. Get a stick of modeling wax and a precision knife, a Dremel and any other tools you need to sculpt. The shape you now give to the wax is also the one that the finished jewel will take.
- You are making an exact copy of the jewel you will get.
- Using an element as a reference model helps you to better define your creation on the first try.
Step 2. Connect three or four "sprues"
In practice, they are wax cylinders that allow the model to melt and come out of the mold during processing. Using some more wax, shape several long cables and connect them to the model, so that they flow out of the model. This step is easier to understand when you see the whole process: the wax will be covered with plaster, then melted and flowed away to leave a void that has the same shape as the model you made; afterwards, you have to fill the cavity with silver. If you don't make sprues, the melted wax cannot come out of the mold and leave its "negative".
- To make small objects, such as a ring, only one sprue is required. For larger pieces of jewelry, such as belt buckles, you may need to make up to ten.
- All channels should come together in one place and must be connected to a base channel.
Step 3. Connect the mold to the base channel using some melted rubber
The various channels join together and you have to fix the mold to the base exactly where they meet; in doing so, the wax melts and exits from the lower end of the mold.
Step 4. Place the frame over the base channel, making sure there is 6mm between the wall of the frame and the model
The frame is a large cylinder that goes over the base channel.
Method 2 of 4: Get rid of the wax
Step 1. Secure the wax model to the base of the frame using more melted wax
The model should remain raised inside the frame, in order to be ready for the casting process.
Note: The excess silver parts that you can see in the video are other pieces that are part of the clasp and do not represent additional sprues or other indispensable elements
Step 2. Mix the dry ingredients of the gypsum material with water following the manufacturer's instructions
Respect the indications of the specific product you bought; it is simply a matter of combining the ingredients in the right proportions.
- Wear a mask or respirator whenever possible when working with this powder, as it is not safe to inhale.
- Move on to the next step when the mixture reaches a consistency similar to that of a cake batter.
Step 3. Transfer the material to a vacuum chamber to eliminate air bubbles
If you don't have a vacuum tool, you can simply let the plaster rest for 10-20 minutes. The air bubbles create holes that allow the metal alloy to filter; consequently, the jewel would have a "pockmarked" appearance.
Step 4. Pour the chalky compound into the frame surrounding the wax model
You have to completely "drown" the sculpted wax in the plaster and put it all back into the vacuum chamber, to get rid of the last air bubbles before continuing.
Wrap the upper opening of the frame with adhesive tape, resting it halfway on the edge of the frame itself; by doing so, you prevent the chalky mixture from overflowing from the bowl
Step 5. Wait for the chalky mold to stabilize
Follow the manufacturer's instructions for drying times to the letter before proceeding to the next steps. When the mold has hardened, remove the tape and scrape off the excess material from the top opening.
Step 6. Put the frame and the mold in the furnace, which has meanwhile reached an internal temperature of about 600 ° C
Note that the different types of gypsum must be subjected to different temperatures; however, they should never be below 600 ° C. In this way, the mold hardens and the wax inside is melted away leaving an empty chamber.
- This process takes up to 12 hours.
- If you have an electronic furnace, try setting it so that it gradually increases the temperature up to 705 ° C; this expedient prevents the plaster mold from breaking.
Step 7. Remove the frame and mold from the furnace while they are still hot and check the base for obstructions
Check that the melted wax can easily come out of the gypsum block and that there is nothing that can close the sprues; if the channels are patent, gently shake the mold and frame to make sure all the wax comes out. You should see a "pool" of wax in the tank of the frame or at the bottom of the furnace.
Remember to wear protective gloves and goggles when doing this
Method 3 of 4: Making the Jewel through Fusion
Step 1. Place your chosen metal in a crucible and melt it in the forge
The melting temperature and time vary according to the type of metal you have decided to use; You can also use a small crucible and a blowtorch to melt the silver.
Step 2. Use a jewelry juicer to pour the metal into the mold
If you want to make pieces professionally, you need a centrifuge that allows you to quickly distribute the liquid metal evenly; however, it is not the only solution available to you. There is the classic and simpler technique that involves carefully pour the molten metal into the channel left empty by the wax at the base of the mold.
You can also use a large metal syringe specifically for this operation to inject the metal into the mold
Step 3. Let the metal cool for 5-10 minutes and then slowly put it in cold water
The cooling time obviously depends on the type of material you melted. If you immerse it too soon in water, you run the risk of breaking it; if you wait too long, you may have a hard time separating the plaster from the hardened metal.
- Do your research to know the cooling times of the metal you have chosen before starting the job. That said, if you've gotten caught unprepared by the situation, you can wait 10 minutes and then put the mold in cold water.
- The plaster should begin to melt as you shake the mold in the cold water.
Step 4. Gently tap the block with a hammer to break up the excess plaster and unearth the jewel
Detach the frame from the base sprue and use your fingers or a toothbrush to remove any remaining bits of material left on the jewelry.
Method 4 of 4: Refine the Jewel
Step 1. Use an angle grinder on which you have mounted a cutting disc to peel off the metal wires that have filled the sprues
Remove any fragments that have formed by filling the small holes you had to make to pour the liquid metal into the mold. A manual angle grinder should be more than enough for this job.
Step 2. Consider soaking the piece in an acid bath or wash to remove any chalky residue
The smelting process often leaves a film of grime and grime on the metal. You can look for some specific substance to wash certain metals, giving them a brighter look and making the subsequent cleaning work easier.
Step 3. Sand any irregularities in the jewel using a rotating brush to polish the metals
Use files, polishes or polishing cloths to clean the piece and give it the look you want; if you plan to set a stone, do it after polishing.
Advice
- To make original pieces, you should sculpt the models yourself from a block of wax using dentist tools or sculpting spatulas to outline the details. You can buy the wax stick and specific tools at any fine art store. There are many different types of wax, some are softer than others; try several until you find the one you prefer.
- Sometimes, synthetic wax is also available in jeweler supply stores and not just fine art or craft shops; search online or the yellow pages to find these retailers.
