Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Silvae77 on 04/12/2014 21:19:08

Title: What would make the best permanent mould material for silver or copper casting?
Post by: Silvae77 on 04/12/2014 21:19:08
Hola all! I would like to produce cast jewelry from silver and copper but I'm stuck on one issue: the mold material.

I would like to find a permanent (or at least semi-permanent) mold material that I can form in two matching hemispheres around an object that I carved or found (i.e. a small acorn, sea shell, etc). In my mind, I'm thinking of either a cement I can pour around each half of the item or an unfired ceramic clay I can mold around each half of the object, then fire to achieve hardness. Once clamped together, these halves would create the die space needed to cast my jewelry with molten copper or silver. This technique would allow me to replicate virtually anything in the world around me that would typically not be workable with lost-wax or green sand casting techniques, and would allow many reproductions from the same mold.

I'm sure someone has done something like this before, but I'm not finding relevant information from my research on the interwebs. I suspect the cement or ceramic approach can work, but I don't know what exact mold materials would work best to withstand repeated exposures to the high temperature of molten silver and copper (+-1800 - 2000 F) and can hold a reasonable level of detail from the original carving or object. I also want to make sure there is no water content in the mold to explode on me. :)

Can you help me out? I would appreciate any resources or advise you could give, and I'm sure others would love to try this technique as well, if it can work.

Thanks kindly!
Title: Re: Permanent mold material for silver/copper casting
Post by: CliffordK on 04/12/2014 22:28:09
Something like Tungsten would certainly take the heat, and repeated use.  However, it may have troubles releasing your material. 

A reusable mold would also have a limited number of flat faces (2 or perhaps 3) from which everything would have to have positive tapers.  A one-time use mold with lost wax casting could support far more intricate features.
Title: Re: Permanent mold material for silver/copper casting
Post by: Silvae77 on 04/12/2014 23:09:58
Thanks for the reply! Well, tungsten wouldn't work for me as I'm looking for a mold material that can "pour" or form around an object that I want to replicate (either a wood carving or a natural object like an acorn). I'm not intending to carve the mold out of a block of tungsten or other material - I'd like to realistically capture the shape and texture of the object I'm casting from an original (such as that acorn).

That's why I'm wondering about a cement compound or clay material that can form around the object. If cement, I'm thinking I could pour half the mold around one side of the acorn, let it dry, then coat the cement surface with a substance to prevent bonding or sticking. Then I'd pour cement onto the dried face of the first batch of cement (and now fully encasing the acorn), let it dry and pull the two halves apart, remove the acorn. Presto - I have a mold! But will molten silver melt away or chip the cement? Hence my conundrum.

Title: Re: Permanent mold material for silver/copper casting
Post by: evan_au on 05/12/2014 12:17:18
How about reversing the thinking?

Rather than cast silver inside a cheap mold, how about plating silver (or other metals) around a cheap mold?

You can now create quite intricate shapes using 3D printing - and these can be customised (like names). The challenge then is to plate onto it.

Just don't sell it as solid silver!