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Anyone used bismuth?


#1

Hi Guys,

Anyone used bismuth?

Got some metal analysis of some very old pieces “mostly” silver
alloy that contains bismuth.

Anyone?

Regards Charles A.


#2

Yes as a component of low melting point casting alloys like
Cerrobend, Woods metal etc. I would guess it will make a brittle
silver alloy like adding tin or lead to silver. Bismuth is a very low
toxicity element for a heavy metal and has a really cool property in
that it expands as it solidifies.

James Binnion
James Binnion Metal Arts


#3

Hi, bismuth doesnt alloy particularly easily with silver, a couple
of percent can be added without drastically changing its properties
but like cadmium it used to be used in solder so I suspect that it is
a contamination from either a soft solder or from a solder from a
continuous process like chain.

James’ point about low melting point alloys like Woods metal is
pertinent as white metal is used for castings in the model world and
for soldering lead and pewter on occasion. Woods metal is pretty
good for making patterns for later moulding with cold vulcanising
rubbers, dental casts (used to-not so sure about now) and for filling
hollow-ware instead of lead.

Nick Royall


#4

I think that bismuth is a common contaminant in pre-modern alloys.
Having said that, the amounts are usually pretty small. As an
example, the Hoxne Hoard contains silver alloys with trace amounts of
copper gold and bismuth.

How old are the items that you’re looking at?

Jamie Hall
http://primitive.ganoksin.com


#5

Hi Jamie,

It was my conclusion too that a lot of these trace elements are the
result of primitive refining techniques.

I’m looking at alloy analysis in “The Viking-Age Gold and Silver of
Scotland” by James Graham-Campbell

The items are in between 850-1100.

Looking at the artifacts, you can determine how they were
manufactured, some very complex patterns created with very simple
techniques.

The reason to add the impurities, as it were, is that some customers
appreciate the extra attention, and will pay.

Kindest regards Charles A.


#6
bismuth doesnt alloy particularly easily with silver 

It’s only a very small percentage, somewhere in the region of 0.1 to
0.7 percent.

Regards Charles A.


#7

I once made a set of wedding rings with core sample gold from a mine
in Cripple Creek, CO. It tested to about 21k with some bismuth. It
made it so malleable that each time hammered the rings round they
stretched enough that I had to cut more out. I did not like its
properties.

Elizabeth


#8
I once made a set of wedding rings with core sample gold from a
mine in Cripple Creek, CO. It tested to about 21k with some
bismuth. 

Good to know, fortunately I’m not mixing the alloy for anything
other than to reproduce a period alloy.

Regards Charles A.


#9

Does anyone know about effects of bismuth in lead-silver
cuppelation? I did see that there was some research on the internet,
but it’s behind a pay wall.

Jamie Hall
http://primitive.ganoksin.com