Introduction: Cast a Metal Ring!
This Instructable is about casting and finishing a ring using the art of lost wax metal casting. In lost wax casting, a wax positive of the final product is carved and embedded in plaster. The plaster is then heated so that the wax drips out. Finally, molten metal is poured into the negative impression left by the wax.
My ring has dual snake heads emerging from the ringband. I picked these because snakes seem to symbolize power, prowess, and deadliness, which are cool to display on a ring. You could use a different design, as these instructions apply for a wide variety of lost wax casting projects.
Your finished product will be shiny, smooth, and handcrafted by you! You could use the ring for yourself, for a gift, for a secret weapon of power, or for displaying your handiwork.
Enough talk, let's get casting!
Step 1: Cast the Wax
First off, you will need some wax to carve into the ring. I just used old broken crayons. Grab a bunch of crayons, remove all the paper wrappers, and place them into some sort of melting pot. Unless you want to spend hours scrubbing wax off of your cookware, avoid using eating stuff. I used a cut-down soup can, and it worked very well. Place the crayons in your melting pot and begin heating the pot over the stove. If you have a range hood, you may want to turn it on now, as melted crayons can make some annoying fumes. When the crayons are all melted, pick up the melting pot with some pliers and smoothly pour the wax into a mold. The mold should be something like a small popcorn tin lid. These are great because they have a small diameter and smooth, straight sides. Thus, they create a nice-sized disk of wax that can be easily removed and carved. Basically, the mold needs to make a chunk of wax that can be removed and carved into a ring. If you pour the wax to be as deep as the ringband is thick, carving will be easier. Once the crayons have been poured, let them cool and then place in the freezer to chill them further. When they are nicely cold (cold wax seems to be easier to remove than warm wax), pop the wax blank out of the mold.
Step 2: Carve It Up!
Before you begin carving, draw a template on paper. If you want swirls, use a compass to get nice smooth curves. This will help you in carving the ring. Additionally, a normal wedding ring can be placed on the paper and traced for the ringband to get an idea of what size of ring will fit. Once you have your drawing. lay the paper on your wax blank and trace the lines with your carving knife. I just used a regular woodcarving knife. Now that the paper template has been transferred to the wax disk, begin to carve the ring. This is one of the most fun parts. Use your creativity and be detailed! Also, be very careful. Crayons are not the strongest things in the world! If you happen to break your wax ring, use a something like a metal nutpick to solder the ring back together. What works great is to heat the metal tool over the stove and then use it to melt the parts back together, sort of like smoothing plaster over a crack in the wall. Once the ring is done, it should be the same shape as you want the finshed ring to be.
Step 3: Prepare for the Plaster
Now take another short crayon and, using the same method detailed in the previous step, solder it to the ring. It works best to solder it to a blank area of the ringband, rather than the snakehead part, as to not mess up the details. This crayon will be the hole you will pour the metal into to fill the ring cavity. After you've done this, take a paper cup and melt some crayon onto the bottom of it. Before it cools, stick the crayon shaft onto this, so the ring stands up on the pedestal. It should look about like the picture above. When the time comes to cast the ring in metal, the mold will be inverted so the ring is facing down, and then the metal will travel from the base of the crayon pedestal down into the ring, which is now above the pedestal.
Step 4: Plaster Goop
Using plaster of paris, mix a batch of plaster and then vibrate it to remove air bubbles. Pour it into the cup and tap it some more to get all the bubbles to rise to the surface. If bubbles attach to the ring casting, they will create voids that the metal will flow into, thus making bubbles appear on the metal product. These are pretty ugly and can be annoying to remove. They could also destroy fine details. Once the plaster has set, tear away the paper cup and let the mold dry for about two weeks. I got distracted with other projects, so my mold probably dried for a month or so. It just has to be absolutely dry.
Step 5: Fire the Mold
Using some sort of furnace, heat the mold strongly for about 30 minutes. I used a paint can with a hole cut in the side as my furnace. A copper pipe was put up to the hole and a ShopVac blew air into the furnace through the pipe. Charcoal was lit and put into the paint can and the mold was put on top. It works quite well for melting out the wax. After the mold has been heated, take it out and put it on a bed of gravel or sand. My mold, as seen in the picture, cracked a fair bit in the furnace. Real lost wax casting uses a bunch of special equipment and materials, but those would probably cost upwards of $2000, so I just made do with what I had. Since I didn't have all the special stuff, my mold cracked some, but it didn't affect the final casting. Now that the mold is hot and void of wax, you're ready to pour the metal!
Step 6: Cast the Ring!
Using the same sort of cut-down soup can from the wax melting step, melt your metal in the furnace. If you have a real crucible you could use that too. My metal was some solder (tin/lead) mixed with some zinc. I had been playing around with alloys beforehand and had some ingots of the tin/lead/zinc alloy. Note that lead metal is poisonous, so wash your hands after casting and finishing the ring. Lead probably wasn't the best metal to use for a ring... :) But I don't really wear these rings that I make much, so washing hands after use is just fine.
When the metal is nicely molten, as seen in the first picture, use long pliers to take it out of the furnace and then use a screwdriver to skim off the slag on top. With the pliers, smoothly pour it into the hole in your mold. My metal began to bubble furiously when I poured it into the mold, so wear safety equipment. I don't know if it was the plaster of paris or residual wax, but something made a bunch of gas that bubbled out through the metal. Eventually, the ebullition stopped and the metal cooled. Allow at least half an hour for it to cool - an hour is probably even better.
Step 7: Remove the Ring
Break the mold open using a hammer and remove your awesome ring! Strangely, the inside of my mold was blue and red colored when I broke it open. Now that I think about it, it was probably the crayons leaching into the plaster during the heating of the mold. I was very pleasantly surprised to see that my ring actually turned out well. The metal filled the ring cavity completely and picked up a surprising amount of detail!
Step 8: Rough Finishing
Now that the ring is cool and out of the mold, take a hacksaw and cut off the stick of metal attached to the ringband. Using a Dremel tool and some sort of cutting bit, remove the rough parts of the ring. Large wood files also work great for this job. Since the alloy on zinc, lead, and tin is soft as far as metals go, shaping the ring is pretty easy. To give more detail to the ring, use smaller files and a lot of patience. Eventually, the ring should look like the wax ring originally did.
Step 9: Final Finishing
Using sandpaper cut into strips, rub the ring to a shine. The sandpaper acts as a smoother to even out any imperfections from casting or carving the wax. By using finer grits of sandpaper, you can acheive a very amazing shine. After you are done with the sandpaper, pick up an old shirt and rub the ring vigorously. This will literally give it a mirror finish! Once you are happy with your final product, admire your handiwork and use it for whatever benevolent or devious purposes you have in mind. Those snake heads look awfully scary...
This was my very first try at lost wax casting. Using none of the specialized equipment, plaster, or tools of the pros, I achieved a shiny, smooth ring that looks awesome. You should try it too! Don't be discouraged if it doesn't look like a storebought gold ring. After all, those don't have snake heads of power and prowess...