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Shibuichi strength - will tiny parts break?


#1

Greetings Everyone:

Leonid said that 14K gold has incredible strength. Does anyone know
how well shibuichi (1/4th silver and 3/4th copper) stands up? Do the
small parts break? How about bronze? How strong is bronze? It looks
like I’m coming into metal work from a very different direction than
most jewelers. My intro to craftwork was making polyclay critters:
charms, netsuke, or micro-sculpture animals. I sculpt models out of
Primo Sculpy, make a silicone mold of these, and pour wax into the
mold. Micro-sculpture is a little too large for pure silver, but
shibuichi is partly a precious metal, and it has a beautiful color.
Will tiny parts break?

Sally Parker


#2

Hi Sally,

Shibuichi is strong enough, you can’t use it to cut steel, but as a
jewellery item it will wear fine.

Bronze is also plenty strong enough, of course it depends on the
type of bronze, what elements go into it’s mixture etc. etc. Bell
metal (a pure 80/20) is a brittle as all get out.

Will tiny parts break (?), depends on the parts and how tiny, and
how much stress you exert upon the pieces.

James Binnon has more experience with shibuichi, best to ask him.

Regards Charles A.


#3

Hello,

Shibuishi will break just as another metal if you put enough stress
into the metal by coldworking without annealing the alloy. The amount
of stress in the metal determines the breakingpoint. Obviously copper
is the source of responsibility for this quick build-up stress.
Copper workhardens pretty fast and you have to watch for little
cracks telling you that you are passing the limits. Shibuishi is a
fine metal with lots of possibility’s but you have to like it.
Annealing the meal is very time consuming because you have to do it
very often. This is something you have to consider when you use it in
mokum=e gan=e however, like Charles already mentioned, there are
other very well educated person in this forum who can tell you more
about mokume then I can.

Enjoy and have fun
Pedro


#4

Shibuichi is a Japanese alloy of copper and silver. The usual
proportion was 25% silver to 75% copper, but for casting purposes the
proportion went down to 10% silver. Shibuichi is a very reddish
alloy, redder than traditional bronze (copper and tin), but not as
red as copper. To me, when shibuichi is polished, it seems like what
copper ought to be if it were a precious metal and were strong
enough to use for tiny pieces. It oxidizes to a walnut brown.


#5

Hi Sally,

Shibuichi is a very reddish alloy, redder than traditional bronze
(copper and tin), but not as red as copper. 

I just want to clarify, you were stating that the casting alloy of
10% silver and the balance copper is the reddish alloy, not
traditional shibuichi?

Never alloyed a 10% silver bronze, I’ll have to give it a try.

Regards Charles A.