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lorenzo

Anyone do any silver casting?

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It's traditional to start with plaster of paris or clay, start with a slipcoat or vibrate to get rid of air bubbles. There are also reuseable casting rubbers available from jeweler's suppliers if you want to get modern.

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Casting has a lot more to it than you would really think, investment has to be burned out to a specific set of temperatures(yeah, more than just getting it hot) and it can't have too much water in it. Investment is specifically designed to take the heat of a kiln, anything else will be destroyed. If you do get to hot, the investment may weaken or crack, if you don't have a complete burnout, some of your model will still be wax and won't get made into sterling. The flask also has to be hot, about 1000* for sterling when you cast, this is to ensure that the metal gets into the whole casting, so you need a kiln for burnout.

My school uses this kind of investment and flasks and bases similar to these.

After you are set, you need a way of actually casting, sling casting would be doable, but gravity pouring into investment will give you some very porous castings and you may end-up with partial castings as well.

There are a lot of things that can go wrong when casting(about 1 in 10 fails), so it can be very useful to find a nearby casting house. You can bring them a wax model and they can sprue it for you, invest and cast, and it's pretty cheap, somewhere around $1/gram for sterling.

Shiz

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Well, my current line of thought involves an open back casting, so that reduces many of the complications. If I come up with some more through designs, I'll take your advice about the casting house.

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There are a few alternatives to lost wax casting, cuttlefish casting is pretty cool, it can take a surprising amount of detail. You can either press something into the cuttlebone(which is actually cartilage) or you can carve something in. The casting process is easy, just heat metal to molten in a crucible, adding flux when the metal starts to completely melt or you can use something such as a charcoal block as a crucible. Charcoal creates a reducing environment as you heat it because it burns giving off carbon dioxide which keeps oxygen from contaminating your metal. Just carve a little bowl type thing into your charcoal block, put your metal in and heat, no need for flux. When it's totally molten, just pour into your cuttlefish.

You can do it open, or closed, meaning you can take 2 pieces, flatten them, then carve something into both sides...put it back together and pour into it. You can also cast in charcoal by itself. carve a design into a charcoal block, put your metal into the carving, and heat. When it's molten, take another charcoal block(preferably flat) and press down on the molten ball. Designs with less detail work well with this approach as you actually have to push the metal into corners. circles work great, but squares are harder. ;)

Oh yeah, you can find cuttlefish bones in most pet stores, parakeets use them to sharpen their beaks. flatten it first with some sand paper, then rub them together to ensure they are flat. I usually use one and cut it in half and it works great. You can only use them ofr one casting, and after taking out your casting, make sure to run it under water to stop it from burning.

Another great method is sand casting, some places sell kits and the amount of detail that can be produced by sand casting is quite amazing, it's pretty simple and you can pour straight from a crucible into the sand/clay.

Shiz

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Cuttlefish casting is great... you can smooth out the texture, or you can leave it (cuttlefish grows in layers, similar to a trees rings). I love the patterns I get from it!

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If you do go for cuttlebones, get the plain white ones. They have some "flavored" ones (but they still stink) and those have some funky coating on them and are brightly coloured. They are pretty cheap and come in different sizes, too. Wal-mart used to sell them, but you can pick them up at any Petco or Pet Smart or the like.

~Angie

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There are also reuseable casting rubbers available from jeweler's suppliers if you want to get modern.

Ignore that bit, silver gets too hot to rubber cast, I started thinking about pewter for some reason.

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Ignore that bit, silver gets too hot to rubber cast, I started thinking about pewter for some reason.

No you were on the right track. Its just that the rubber is used to create new molds. So you can do many duplications.

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No you were on the right track. Its just that the rubber is used to create new molds. So you can do many duplications.

I know, but with lower melting point metals you can also cast directly from the rubber, with silver you will still need gypsum-based investment.

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I haven't done any silver casting in nearly 20 years, but without access to decent equipment, I always had my best luck with cuttlebone. For me it was free (a quick trip to the beach would be enough to find all I needed), and it is very easy to work with. The downside is that the technique is almost entirely different, you typically either carve the design directly into the cuttlebone, or have a male blank that you press into it to make the mold, then carve the sprues etc...

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