A couple of weeks ago, I was feeling a bit smug because, when
someone asked about melting finished pieces, I had not melted
anything irreparably in a long time. Well, pride goeth before a
fall!
I made a marriage of metals belt buckle for my son, and used brass
in it. I forgot how the least extra heat causes brass to kinda
collapse, when it is in contact with other metals…
I re-made the buckle with just copper and silver, and it came out so
nice I want to do some more MOM pieces.
This is where you guys come in.
I have some “antique bronze” casting grain. If I make sheet out of
it, will it behave the way the brass did? I’ve never used bronze,
but I’d like to widen my choices for colors.
Also, I want to make some shibuichi and shakudo. I’ve never done
alloying before, but I know the basics… that is, I know how to
prepare the ingot mold, and I believe I’m supposed to melt the
higher-melting material first, then add the lower. Uh, right? I’ll
check Oppi before I start, but will be happy to have any advice
anyone cares to pass on.
In your marriage-of-metal piece, did you use IT solder? I’ve had no
difficulty marrying brass, bronze, nickel-silver and fine silver in
one piece using IT. Have had a couple of ‘accidents’ using just hard
solder. The brass worked just fine, but an interesting thing happened
with one piece that I did: I had used IT and everything came out just
right, but I left it in the pickle a bit too long, the brass pitted
and I just let everybody assume that it was an intentional texture.
Bronze was easier to join than brass, by the way.
Brass in married metals can be a problem because when soldered to
silver it is very easy to overheat and diffuse the copper and zinc,
which is the brass into the silver, which makes the same alloy as
your silver solder. Brass and copper is much easier than brass and
silver. You can still do it, but you just have good reflexes to pull
away the torch just as soon as it it flowed. Brass and silver does
not contrast as well as silver and copper and as it patinas the brass
tends to look tarnished and spotty while the copper naturally takes
on a more robust color. For a bronze color I would suggest
"commercial bronze" which is actually red brass. 90% copper, 10%
zinc. The Japanese alloys work well but avoid the higher silver
shibishi alloys as they melt lower and really do not offer such a
good color contrast.
When married metals was what I was all about, I used high (75%)
silver solder. About 5 years ago I rethought this and started using
medium (70%) solder as the first and main solder in my pieces. I
think in general medium works much better because you are less likely
to overheat when using it. When you solder copper alloys to silver,
the solder reacts differently. This is because the solder absorbs
some of the copper (and zinc, if it is brass) which lowers the flow
temperature of the solder after it starts to melt and if you remelt
it. You may have heard that silver solder re-melts at a higher
temperature after it has been used. This is true if you are joining
silver to silver because a small amount of the base silver is
absorbed into the molten solder, which raises the silver content. Use
silver solder on copper alloys and just the opposite happens. the
remelt temperature becomes lower.
The older Oppi book shows the Mexican married metals "flooding"
solder into the joints. Not such a good idea in my book. Use enough
solder, but avoid the flood. I have run into many people over the
years who have taken that single word as gospel and made their
married metals a messy and difficult process just because they
thought that flooding solder was the way to go.