Soldering for Jewellers
The first example will explain the general principles
of soldering. The edge to edge joint is the
weakest of all joints and it is worth considering
how you would make this stronger for some
applications. For example, a ‘scarf joint’ is when
the metal is cut at an angle, allowing a larger
surface of the metal to be joined, and a ‘step
joint’ is when the ends are cut with two levels,
ov e r lapping the edges. These are sometimes
only possible with thicker sheets of metal and
with practice, as precise work is required. Other
options could be considered to strengthen the
joint that affect the aesthetics and it is worth
considering how the added details will add to
the overall design. For example, the edges can
completely overlap each other or an extra piece
added overlapping both ends; this is often called
a ‘strap joint’.
Joining pieces of flat metal
A variety of joints.
Wet or dry the edges.
Wash your hands to ensure that the flux or
work does not get any gr ease or dirt on them.
If needed pin the work to the heat r eflective
Flux the joint.
Place the solder so it will be easier to clean up
Heat the work with a bushy flame, if your torch is
not adjustable start with it a little further away.
Remove the heat when the solder has flowed.
Let the work cool before moving it.
Then cool completely in water.
Place the piece in warmed pickle solution.
Remove from pickle when oxides and flux
residue have gone.
Rinse to remove any traces of pickle.
Use a bushy flame
Remember the equipment section of
this book, which stated ‘the lower flow
temperature of the pewter solder will
create a weaker bond more like glue’ when
using it to solder other metals. A pointy hot
flame heats silver solder too fast, creating
a similar bond. It causes the solder to flow,
but not permeate the surface of both pieces
of metal. This may be strong with a little
wiggle test but later one piece may break
cleanly away from the other.
Place a small piece of solder overlapping the
joint; take some time to think about this.
Consider where would be the easiest place to
clean up the solder if it flowed a little in the
wrong direction. For this example, the solder
is placed at one end of the joint, as it is easier
to clean the end of the finished item rather
than the middle. Hard solder is used as this is
the only joint that is going to be made on this
Heat the metal with a bushy flame; this is
known as a reducing flame, which means it is
using a lot of fuel and in turn absorbs the
oxides that stop the solder flowing. The
bushy flame will allow both pieces of metal to
be heated at the same time to the same
temperature. There is no advantage of
heating it up fast with a hotter flame. Apply
the heat to the whole piece, moving the
flame constantly across the work as if painting
the metal with the flame. Use the midpoint
of the flame rather than the tip or right up to
the torch end and move away a little if the
metal is heating up too fast. Remember to
heat the metal not the solder; the metal
should be able to transfer the heat to the
solder. If both pieces are the same temperature
the solder will flow along the joint.