Pewter casting involves melting pewter, which is a mixture of mostly tin and sometimes silver, antimony, lead, or any number of alloying metals that can make the tin base either harder or softer, melt at different temperatures, or add sharpness to details in the casting. Pewter melts at around 230 degrees Celsius, and is best poured at 325 degrees Celsius, depending on the alloy. Most modern pewter alloys do not have lead, and are safe for human use. If you don’t know where the metal came from though, assume it has lead in it.
Melting Metal
I melt my pewter in a cast iron ladle, heated with either a propane or MAP gas torch. Once the pewter is fluid, I cast it into the mold using a dipper, or sometimes just an old metal table spoon. The pewter will freeze almost immediately in a cold mold, but may take some time to set up fully once the mold is hot after multiple casts. Be sure that the pewter is solid before opening your mold to prevent coming in contact with molten pewter.
Molds
Molds for pewter casting can be made from a wide variety of materials. I have used wood, cuttlefish bone, casting sand, soap stone, and copper to temporarily hold onto the molten pewter until it freezes. There are more modern methods, but I have never tried them. Soap stone is my preferred mold material. A mold carved from soap stone can make a thousand or more casts, holds sharp detail, and can be easily pinned together to provide consistent positioning of the mold halves when they are taken apart and put back together again. In soap stone molds the pins are carved out of the stone and poured in place with molten pewter.
Finishing
Pewter bits come out of the mold very bright and shiny. There is often a bit of finishing work to do however. Bits of pewter that where part of the pouring spout on the mold become sprew. Any pewter that slipped out the edges of your casting is called flashing. I remove the sprew with a pair of side cutters, and the flashing with a file, or razor knife. Sometimes, if your casting has a hole in it, such as a pendant, the hole will have to be cleared out with a drill bit or small file.
Wearing
Pewter tarnishes differently depending on the mixture of metals used to make it. Some pewter will tarnish almost immediately and may leave some marks on the skin similar to silver. Some pewter tarnishes slowly, and may not leave any noticeable marks on skin. All of them can be shined up again by using a commercial polish. Pewter will scratch easily compared to other metals; it can also bend if your casting is thin. Don’t worry though, it can be bent back, polished, or if it gets really damaged, melted down again and recast!
Sources
- Geoff Carn. "Pewter." carnmetl.demon.co.uk. Accessed 5/27/11
- Prince August Casting Metals. "Low Melting Point Alloys." carnmetl.demon.co.uk. Accessed 5/27/11
- Darrell Markewitz. "Pewter Casting in Stone Moulds." warehamforge.ca. Accessed 5/27/11 ml .
Aaron Rankin - Aaron Rankin
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