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.