I wanted to add some custom accents to a Texas A&M themed nightstand that I was building. I thought it would be cool to cast my own knobs using my Aggie Ring as a template. This Instructable will take you through the steps and materials that I used in the process.
Step 1: Choose a Template:
The first step in this process is to find a template that you want to use. Your template could be just about anything. I chose my Texas A&M Aggie Ring.
Step 2: Take an Impression of Your Template:
For step two, you will want to create an impression of your template. If your template does not have a lot of detail you can you Alginate; however, if your template has a lot of fine detail, it is best to use a polyvinyl siloxane (PVS) material. I used "Dentsply Aquasil Light Body PVS" but any PVS material will do. Fun fact: this is actually the same stuff that the dentist uses to take impressions of teeth. The material comes with a "gun" and you just squirt the material over your template. Be sure to keep the tip of the impression gun in the impression material as you are covering the surface of your template in order to prevent air bubbles. After you have covered the surface of your template, remove the impression gun and let the material dry (this usually takes about 5-7 minutes).
Step 3: Pour Wax Into Your Impression
Take a small metal container, fill it with wax and heat it over a flame until it melts. I used "Inlay Casting Wax" made by Kerr Restoratives. Once the wax is melted, pour it into your impression and let the wax get hard again. After the wax becomes hard, carefully separate it from the PVS material. The result will be a wax replica of your template.
Step 4: Prepare Wax Patterns for Investment
Add a wax sprue former to each of your wax patterns, then attach each sprue former to a crucible former. Next attach the crucible former to a casting ring. I did not use a ring liner for this project. Now you are ready to invest your wax pattern.
Step 5: Investing Your Wax Pattern and Burnout
Essentially, "investing your wax pattern" involves surrounding your wax pattern with stone. To do this, I used a material called "Cristobalite" made by GoldStar Powder. This material is a powder, and you mix it with water to create "liquid stone" which is then poured into your casting ring so that it can surround the wax pattern. After about 40 to 60 minutes, the stone becomes hard again and your wax pattern is ready for burnout. For the burnout phase, remove the crucible former and place your casting ring in an oven programmed for 1200 degrees F for 60 minutes. This will cause all of the wax to melt out of the casting ring.
Step 6: Casting
Casting involves melting a metal down to its liquid form and then pouring that liquid metal into your casting ring where it will take up the space that your wax once occupied. Below is a link for a video to watch the process (in this video they are casting gold rings instead of furniture knobs, but the process is the same).
For my project, I used gold technique metal (an inexpensive gold analogue).
Step 7: Polishing
After you recover your casted metal, you need to polish it. I used a dremel and a series of sand paper discs (rough, medium, then fine) to smooth the surface and remove any small imperfections. Then I used a rag wheel with rouge to get a high shine. This is essentially the last step and your final product can be easily converted to a knob for any furniture piece.
Step 8: Conclusion:
The knobs could have easily worked as stand alone furniture knobs but I ended up deciding to inlay the knobs into a piece of wood to make them a little larger and add even more detail to my project. Hopefully this Instructable has provided you with a little inspiration on how creative you can be with wax castings. The same process explained here can be repeated for all sorts of things like jewelry, art, and statues.