When a ring only needs to be sized up by a
small amount, you can easily size the ring by stretching. This is the
perfect way to size a plain ring that doesn't have any gemstones and is made of
only one type of metal, as it will save you time and money.
Before beginning, it is very important to check
both sides of the ring on a mandrel to be sure that they are both the same size.
You will first want to anneal the metal, as
this will make the stretching process ten times easier as the metal will be more
malleable and less likely to crack under pressure. It is best to fire coat the
ring to protect the finish before annealing. Heat the ring with a soft flame;
this will cause the fire coat to seal on the ring. Continue heating to anneal
the ring, when the metal glows faintly red you have reached annealing
temperature and you can quench the ring in water.
Once the ring is quenched, place the ring in
the pickle to remove the boric acid coating. Rinse and dry the ring before
enlarging the ring.
The quickest way to stretching a ring, is to
use a ring-stretching device. Before sliding the ring onto the ring sizing
device, measure it on your mandrel to be sure of the size. Then wrap a small bit
of regular paper around the device and slide the ring on top. This will protect
the inside of the shank from getting scratched. Pull the lever to expand the
splines of the device; this will begin to stretch the ring. As this device
applies a lot of pressure, the ring will change size very quickly, so close the
splines and remove the ring to check its size often. Don’t forget to flip the
ring over and stretch it from the other side to ensure that both sides are sized
to the same point. DO NOT work too quickly and overstretch the ring!
Once the ring reaches the desired size, check
for any distortion marks. The more you stretch a ring, the more likely it is
that there will be signs of distortion. Sand and polish the ring to remove any
distortions and return it to its original luster.