Who knows anything about spelter alloy, as commonly used for cheap fake
All I know is that it's either zinc or zinc-based alloy, and that it
appeared in the later part of the 19th century when the price of zinc
metal fell, owing to new smelting processes. It's cast at a lower
temperature than bronze, making the moulds cheaper. When suitably
patinated it also made an acceptable fake bronze for mass-produced
Now there's another couple of well-known zinc alloys - Zamak/Mazak and
their precursors. These were used for diecasting, most famously for
diecast toys to replace lead. As is all too well known amongst
collectors, the alloys before Zamak have a failure mode where they crack
and distort after some years of age. This is caused by inter-granular
precipitation of iron impurities in the zinc alloy. Zamak fixed this by
being based on a very high purity zinc alloy, newly obtained from an
improved smelting process with an extra reflux purification stage.
My question is this - If diecast zinc alloys of the early '30s don't
survive, how does the older and presumably cruder spelter alloy manage?
What's in it? How does it avoid these damaging impurities?
- posted 16 years ago