Sunday, February 13, 2011

Lost Wax Casting - Doing It On Your Own

By on Sunday, February 13, 2011 4 Comments

Born bronze - Bronze castsCasting via Wikipedia
This Guest Post is by Leon Harris who writes for Pennsylvania Precision Cast Parts, a leading medal casting manufacturer specializing in the lost wax casting process.

There are plenty of ways to design and make your own jewelry. Most novices begin with simple beading, whereby they purchase ready-made materials (charms, beads, chains, closures, etc.) and assemble them into finished pieces. Some people even get crafty by purchasing a small furnace or forge to turn their own glass beads.

But if you want to take your hobby to the next level and make something a little more professional and unique, you should definitely consider lost wax casting as a potential method of creating the pieces you see in stores.

There are a few pieces of equipment you’ll need to secure, but here are the basic steps to getting it done.

1. Create a model
The first and possibly most important step in the casting process is creating your original model, since it will be the three-dimensional blueprint for your final piece of cast jewelry. You need to take special care in choosing the right wax for modeling, so you will likely need to experiment to find the composition that works best for your style (you don’t want it to be too malleable or it may lose its shape, but you also don’t want it so stiff or brittle that delicate parts break off).

Wax Model

2. Sprue and base
Once your model is complete down to the last detail, you need to set it up for molding. You’ll attach the model to a wax pole known as a sprue, which in turn attaches to a base. The base is generally part of a larger assembly that includes a type of flask. Once you have your model rigidly held in place above the base, you can fit the flask onto the base, thus creating a receptacle for the molding material.

3. Create the mold
The next step is creating the mold, and it’s pretty simple. The most common material for molding is plaster, and you can make it by adding water to plaster powder and mixing it to create a thick liquid, which you pour into the flask, surrounding your wax model. When the plaster is set, you can drill or chisel through it until you find wax, at which point you will put the entire structure into a kiln to melt the wax out, leaving a cavity with a negative of your model imprinted on it.

Removing wax model

Mold
4. Two types of casting 
From there, you have two options for casting (i.e. pouring the molten metal). The first method is centrifugal casting, in which metal is heated either by forge or by blowtorch, placed in a box attached to the mold at the end of a long swing-arm (generally inside a drum of some sort), and the whole assembly is spun to force the metal into the mold through centrifugal force.

Pouring Molten Metal
 Alternately, you could opt for vacuum casting, by which an air-tight chamber is created by attaching a pump and air-pressure assembly to the mold (this requires specialized equipment, but it may show a higher metal yield than centrifugal casting).

5. Finishing touches
Once the metal has been cooled inside the mold (generally by dipping it in cold water) you can crack the mold to reveal your treasure within. If all has gone well, the result will be an exact replica of your model (albeit attached to a metal sprue that you’ll need to remove). From there, you simply grind and polish your jewelry to perfection.

Polishing

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Original Post by THE BEADING GEM
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4 comments:

  1. Very informative post! I am nowhere up to that level yet but saving it for the future.

    ReplyDelete
  2. So am I although I am not sure if I am going to be any good with making 3-D wax sculptures! But it's good to know there are casting services out there once one can master the wax and mold stage!

    ReplyDelete
  3. I've always been in awe of the metal artists that brave glowing white, molten ore from which they craft their masterpieces. I also revere the glass artists who turn and sculpt and blow an incredibly hot glob of liquid glass into a thing of wonder and beauty. To me this is an entirely different level of jewelry making. I doubt I will ever attempt this level as I am a hazard around my own kitchen stove and am constantly burning myself trying to retrieve something from the oven or the broiler. I shouldn't even mention the many loafs of garlic toast that I've cremated, a few came out flambéed...a dramatic presentation but totally inedible. =O

    ReplyDelete
  4. You too? I also have to watch my garlic toast like a hawk otherwise they are incinerated!

    ReplyDelete

 

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