A butt joint is probably one of the simplest
sizing methods for joining sizing stock and the shank of a ring. A butt joint is
when both the shank and the stock meet with flat surfaces at the seam. There are
two different ways to create a butt joint. One is done by creating a piece of
stock that is angled inward to match a wedge-shaped opening in the shank. The
other method is making the ends of the stock straight so they are parallel to
the open edges of the shank. This method allows the stock to be held in tension
between the two halves of the shank.
When you are sizing a ring down, the cuts you
make should be just slightly smaller on the inside of the shank so that the two
sides converge at the center of the shank. Through doing this you will be able
to eliminate most, if not all, of the filing typically necessary to align both
ends of the shank before you solder.
A dovetail joint is an alternative to a butt
joint, some jeweler’s prefer this method and believe that it is superior and
worth the extra effort needed to accomplish a dovetail or other ‘non-linear’
seam when they are adding new material to a ring. To create a dovetail joint,
first you must file a negative V or C into one side of your sizing stock and a
positive V or C into the shank so that the metal touches on more than one plane.
Once created, this type of seam is nearly impossible to break, though any seam
that is well done will create the same sort of security.
Fire coating is the process of coating a ring
with boric acid before repair to protect the polished finish of a gold or silver
piece. Never fire coat platinum alloys as it will be detrimental to the metal.
To fire coat a ring, first you will dip it into a “thick slurry of powdered
boric acid in alcohol or coat the ring with Prip’s flux”. Then set the ring on a
charcoal block, or grasp firmly in a pair of metal tweezers and ignite the
alcohol. The alcohol will burn away leaving an even coating of boric acid on the
surface of the ring. When heated, boric acid will turn to a light glaze on the
surface of the jewelry and keep the solder from flowing where it shouldn’t. The
glass-like coating that the boric acid creates will protect the metal and
prevent it from oxidizing. When you are ready to remove the boric acid, place
the ring in the pickle. The pickle will remove any trapped oxidization and the
glaze created by the boric acid, leaving the ring as good as new.
Forming Sizing Stock:
If the sizing stock is narrow and cannot fill
the seam, it will have to be shaped to fit the gap. You can use a mandrel to
help form the material to fit the curvature of the ring.
Inserting Sizing Stock:
Occasionally you will come across a sizing job
that requires a very small amount of metal that is the same size or even
narrower than your sizing stock. When this happens, the most convenient solution
is usually to trim the stock you have to the correct size and insert it into the
seam, solder it, and then remove the excess.
Ring sizing stock can be ordered from jewelry
suppliers and it comes in a wide range of karats, colors, shapes, and
dimensions. When you are preparing to choose a piece of stock for a ring, it is
important to consider the rings many characteristics and to choose a piece that
best matches the ring. You want the piece of stock to be a little thicker and
wider than the shank itself. The piece of stock that you are going to add should
also be clean, preferably you want to use new material from a supplier or from
metal you have alloyed yourself. When you reuse a piece of metal from another
ring, you are running a risk because you cannot be completely certain of the
piece’s metal alloy composition.
If you are preparing to size ring and you
notice that it has been previously sized, there are several things you will have
to take into account before you begin your work. If the existing seam will not
be removed during your sizing work, it will be necessary for you to use a grade
of solder that has a low melting temperature. This way, you will avoid heating
the rings so much that the previous solder begins to flow. Unless you are
familiar with the ring, and worked on it previously and know what solder was
used in the existing seam, it will be necessary for you do use a medium or low
solder, estimating lower than you believe to be necessary to avoid allowing the
previous solder to flow.
Start with a pair of dividers and using the
gauge found on most mandrels or on a small sizing gauge on your bench. Mark out
the number of sizes that you wish to go up or down. If you don’t have a gauge
you can judge the distance using a slide caliper or metric ruler. This can be
done because you know that one ring size is equal to 2.54 mm. Once you have set
your dividers to the correct size to represent how much metal needs to be added
or removed you are ready to transfer this measurement to the ring. Take the
dividers and firmly pull them across the metal in the center of the bottom of
the shank. You will be removing the metal that lies in between the two lines
that you just drew on the metal. If you are adding metal, follow the same
process, only on the piece of metal you wish to add to the ring. If there is a
seam from a previous repair in the ring, make sure that the seam lies in the
section that you will be removing.