Interesting!
Not up on some of this, so pretty much a learning curve for me. Welcomed though, as i am interested in silver,and gold items myself.
As i understand it, Silver has a melting temperature of 1763 degrees Fahrenheit, Bronze similar.
Some links that maybe of interest:
http://en.allexperts.com/q/Jewelry-Gems-Minerals-689/melting-point-gold.htm
http://www.solidsolutions.com.au/customer_services/1_mould_making_methods.pdf
http://www.essortment.com/hobbies/creativehobbyh_ttxi.htm
http://www.ehow.com/how_2155945_make-metal-clay-jewelry.html
I use GRP resin frequently, and use an extractor system, and chemical mask. Aswell as eye, and body protection. Fairly in expensive.
For what i do, hard GRP molds are the way to go. An average GRP mold will yield in excess of 120 articles. These can be multi piece molds aswell, allowing for greater precision, of more complex shapes.
Bakelite? Or
http://www.industrialpolymers.com/trans_casting_compounds.html
Additive sculpture allows for greater dimensions/ experimentation. Quite forgiving, compared with its counter part.
However, there is something magical in the revealing of a shape, with the subtractive method. (As there is with both.)
Its typical that you can visualise a shape/object in the "block" you are starting with.
Example of additive, plug, courtesy of me.
Example of resin article, courtesy of me.
The problem being also with resin is air bubbles.(Can be eliminated) These can distort article , on a small scale though. Im not that bothered with bubbles on articles, as the lions head . The heat , when using resin on its own, can lead to slight overall distortion. There are guides for catalyst percentages, in various air temperatures. Resin also tends to shrink , very slightly.
