How to make a Green Lantern ring- including a glowing version!

Step 7 Casting the silver ring

So what do you do if you want something more durable than a resin ring? Cast it in silver!

It's pretty uncommon for people to have this type of specialized casting equipment so I'm keeping this part pretty short- it's really just here to give people some idea of the processes involved. My recommendation is to carve your wax model and take it to a local jeweler or trade school and see if they will cast it for you.

To cast the ring in sterling silver first the wax model of the ring is attached to a sprue base. Unlike resin casting there is only one sprue attached to the bottom of the ring. This then has a steel flask placed around it.

Next a ceramic casting investment is mixed, vacuumed and poured into the flask and then the flask is again placed in a vacuum chamber to remove any air bubbles.

After an hour, the rubber base is removed and the steel flask is placed into a burnout furnace overnight. The wax will melt out of the ceramic, leaving a cavity for the molten metal to flow into.

The next morning the flask is pulled from the oven and is placed into a centrifugal caster. The proper amount of silver is placed into the crucible in the caster and is heated with a torch until molten.

The caster is then spun and the centrifugal force throws the metal into the ceramic mold. The steel flask is then removed from the caster and is set aside to cool.

After a couple of minutes the flask is placed in a large bucket of water and the ceramic dissolves, leaving a cast silver ring.

The rough casting then has the casting sprue cut off and is cleaned up using a Dremel/flexshaft tool and sandpaper.

Comments

[Drewbaccaa]

I have a gas forge that gets to 2500f how hot do you need this to be for silver.... I also have a kiln... which would be better?

[Honus]

That's easily hot enough- the trick is that the burnout oven has a ramp up cycle so it goes from 300 degrees and holds it and then up to 600 and holds it and then goes up to 1300 for burnout and then goes back down to around 900-1000 degrees for casting. All of this happens over several hours- I usually set up the oven so it turns on around midnight and then I'm ready to cast in the morning. Melting of the Sterling Silver is actually done using a gas torch- I've never cast Silver using any other method. Sterling Silver flows around 1650 F depending on the exact alloy.

[ardrhi]

Wow. A friend of mine had an oven like that in his dorm room at college. It got to insane temperatures. He used it to bake frozen pizzas in about 5 minutes instead of 20, and they were amazingly delicious. He got it out of the chem lab's trash, and was always worried a little about what kind of weird chemicals might be leaching out of the walls when he used it for food.

[Dr_Defenestration]

This is an excellent tutorial. Thank you so much for posting this. I was just wondering in the ballpark how much it would cost if I were to enlist a jeweler to cast my sculpted ring in silver?

[Honus]

Sterling Silver averages around $1.25 per gram for castings so take your wax weight and multiply that times 10.5 (specific gravity of Sterling) to get your casting weight. Of course that doesn't include any sprue removal, flask charges or cleanup costs. I'd take it into a local jeweler and see what they say.

[Dr_Defenestration]

Thank you so much for your quick response. I alas have another question. Upon reviewing the available wax, would I be better for opting with the 1" x 1-1/8" or the (hard version) or the 1-3/16" x 1-5/6." Any assistance would be greatly appreciated.

[Honus]

I'd go for the larger size- it's always a lot easier to remove wax than to try and add wax to make a larger piece.

[Wolfdagon]

The description on that link says "A square inch of sterling silver will weigh 5.457 troy ounces." Can I assume that they mean a cubic inch, since a square inch would have no height. Also, how much silver is required to cast one ring?

[Honus]

How much Silver is required is completely dependent on the weight of your wax model. Take your wax model weight in grams and multiply that by 10 (specific gravity of Sterling Silver) to get your cast ring weight. You generally have to include the weight of the sprue as well. Most of the rings I've made were in the mid 20- 23 gram range.

[wetkiss]

 I was wondering if you could tell me were I can get the silver if I wanted to cast it at home. My friends and I are doing a Green Lantern group and are going to all be different lanterns. This tutorial has really helped us a lot. thank you.

[Honus]

You can get it here-
http://www.ottofrei.com/store/product.php?productid=14265&cat=0&page=1