I will share a little knowledge I have gained on this subject. Pour large and work down for final shape and finish. The first pewter bolster I poured I formed it out of light cardboard. Like the kind you find on a spiral notebook, (the outside covers). I taped it with masking tape and it done just fine. I had alot of file and sand work to shape it correctly.
This was poured from a couple of pewter items I found at a flea market. I then found a bunch of silver solder at a flea market so next pour I added it too the mix.
Once I added that it seemed I had to get the pewter mix hotter to reach molten. Everytime I tried to pour it in a cardboard and masking tape mold it was so hot it would burn through the tape. If I let it cool the mold would not fill out completely.
After a couple of unsuccesful tries I went to Hobby Lobby and bought some Scupley clay. Be sure to get the kind that can be formed and baked according to the directions. When using a mold if the mold has any moisture in it and the hot mix hits it the mold may explode. Thus the reason you can't use regular clay.
I then made a form from the Scupley baked it and poured into it. The mix was still so hot that it burned the mold so the outside of the form came out pitted. The Scupley is some kind of a polymer, so even though it has been baked it has the properties of rubber.
No problem though as it still had to be shaped. The silver solder allowed for a little more shine to the final product but I also think that is the reason the molten temp increased to the point of causing my tape molds to fail.
Hope some of that info may help. It is easy to work with. I think pure pewter will not shine as much but the molten temp is probably less too.
Here is a link that may have some useful info on the subject even though its not about knives.
http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/217305/post/525523/hl//fromsearch/1/
