How to keep your pieces in position during soldering. by Sara M. Sanford

Reverse action tweezers open when you apply pressure and close automatically. Shown at left are sharp, blunt, and serrated points; center, straight, and curved points with fiber grips; right, tweezers mounted in a convenient "third hand," leaving both human hands free.

SOLDERING BASICS

Solder Flux Flux Redux Fit and Cleanliness (a.k.a. solder will not fill gaps) Solder Joints and Placement Steady Soldering

Reverse-action tweezers open when you apply pressure and close automatically. Shown at left are sharp, blunt, and serrated points; center, straight and curved points with fiber grips; right, tweezers mounted in a convenient “third hand,” leaving both human hands free.

One of the essentials of soldering is heating the solder until it flows. Another essential is the precise placement of the pieces of metal you are trying to solder together so that they become joined the way you want them to be joined. But because one or more of your pieces may virtually be floating on liquid solder once it has become molten enough to flow, the piece or pieces may shift position just as you are joining them. There are several things you can do to minimize this tendency and keep your joins precisely placed. (For details on where to place solder and how to heat it, see “Solder Joints and Placements,” December, 1999.)

As it does with everything else, gravity plays a role in soldering, so keeping all pieces as level as possible will help prevent them from floating “downstream.” Even if the two (or more) pieces being joined are not level to begin with for design purposes and the fit is especially critical, there are several ways to keep them from shifting.

One way is to raise “stitches” of metal on the base piece with a graver. These little bumps or prongs will hold the other piece or pieces in place while heating. To create stitches, first scribe a line on the base piece, tracing the outline of the top piece on the spot where you want it to be soldered. This will work on either a flat or a gently curved surface. Again, gravity will take over if the curve is too steep or the top part too heavy.

Using a pointed graver (or a knife or onglette shape), and working from the inside of the scribed line, dig the point of the graver into the metal at about a 30° angle. Just at the edge of the scribe line, push forward only slightly (less than half a millimeter), and then rock the graver upward, raising a sharp point of metal. Do this on at least three points around the scribe line, checking the fit each time. Only a very small stitch is necessary, and a small stitch will just disappear into the solder joint. With a bezel, the stitches can be placed inside rather than outside: scribe a line inside the bezel, and raise the stitches from the outside inward.

Another traditional way of holding pieces in place while soldering is to use binding wire. Binding wire is a soft, iron wire, which is sold in various gauges. Its primary use is in making large hollowware pieces, such as holding a spout to a teapot while soldering. Binding wire can also be used on smaller pieces but must be used with some forethought to prevent marring. Also, being a ferrous material, iron binding wire cannot be put into the pickle, so it must be removed completely before pickling. (There is a stainless steel binding wire available, which, while more expensive, will not contaminate pickle.)

Because solder will adhere to binding wire quite easily, if the binding wire crosses a solder seam, even a previously soldered seam, the wire may become attached to your work, so it's best not to let the wire cross a seam. If this situation can't be avoided, solder that seam first and then raise the wire above the previously soldered seam by placing pieces of scrap metal on either side, thus bridging the joint. A thin coat of yellow ochre paste painted on the solder seam where the binding wire will cross it will also keep solder from adhering to the wire.

Choose a gauge of binding wire that will bend easily, yet is not so thin that the torch will burn through it: 22 to 28 gauges are the most useful in jewelry. Cut off a piece long enough to wrap around the parts to be secured, plus about three inches. Wrap the binding wire around the pieces loosely and twist the ends of the wire closed, but not tightly. Then, using round or chain nose pliers, make an “S” bend in the wire to tighten it just until the pieces are held securely in place. Binding wire that is too tight may cause a delicate part, such as a bezel, to collapse when heated to soldering temperature.

Pins in a soldering coil are probably the most useful holding device (a soldering coil is a coiled strip of heat-resistant sheet material, held in a shallow metal pan). Regular straight pins used for sewing work well, but be sure to use only steel straight pins; some straight pins are nickel-plated brass, and these will melt. There are also larger (longer and heavier gauge) straight pins and T-pins available in most sewing supply stores.

Straight pins can be bent with pliers to any shape and placed in the grooves of the soldering coil to hold almost anything. Be sure to keep the pins away from previously soldered joints or they may become attached. If the pins do become soldered to the piece, remove them completely before you place the piece in the pickle.

Tweezers of various kinds are indispensable for soldering. The regular straight tweezers will let you hold a small part while a larger base is being heated, and then will let you lower the part into position when the soldering temperature is approached. Even easier to use are crosslock tweezers, which require no hand pressure to hold items firmly. In addition to being held in the hand, crosslock tweezers may be propped up on a heat-resistant surface like a charcoal block or fire brick. Crosslock tweezers may also be held in a separate stand, called a “third hand.” Since steel will conduct heat, although at a much slower rate than silver or copper, I recommend using crosslock tweezers with an insulating grip, to prevent scorching your fingers. And remember not to put steel tweezers into the pickle!

One word of caution: crosslock tweezers with a very strong grip may mar metal when heated to soldering temperatures, but you can relax that grip. First, heat the tips of the tweezers to red-hot and then let them air-cool, which will anneal or soften the steel. Then bend the tips until you adjust the strength of the grip so that it will hold metal firmly without marring it.

Stands that hold two alligator clips in adjustable arms can be useful. Just be sure to anneal the clips (heat to red-hot and air-cool) before using them the first time, or they may damage your work.

Another handy product for soldering multiple small parts, such as heads for stones, is soldering investment. Caution: for this procedure, you cannot use regular casting investment or plaster of Paris, which could explode when heated to soldering temperature.

To use soldering investment, place your parts face-up in plasticine (modeling clay) or soft wax, positioned exactly as you want them, and build up a small rim of clay or wax around the parts. This works especially well for soldering many tiny heads together, as it keeps them perfectly aligned: you can shape the clay or wax to duplicate the curve of a ring, for instance.

With your pieces in place, next mix the soldering investment and pour it over the parts. When the investment hardens, in about an hour, carefully peel the wax or clay away, leaving the backs of the parts exposed. After cleaning thoroughly (both wax and plasticine are oil based) with a steam cleaner or solvent, use the torch to heat the investment all around the parts to make sure it is completely dry. Then flux and solder as usual. After soldering is finished, break away the investment, pickle, and clean.

There are a number of other products that can be used to hold parts in place while soldering. Pumice lumps or Carborundum grains in a small pan will permit you to “nest” odd-shaped parts that need to be joined. A non-asbestos powder mixed with water (such as “Extra Hands”) can be molded like putty and used to support small parts while soldering. Odd bits of charcoal block or fire brick can also be shaped to help support parts. Any of these need to be used with some caution: some will scratch metal, while others may either reflect heat or draw it away from the items to be joined.

Whichever soldering aids you choose to use, be sure you understand their limitations!

Sara M. Sanford is a professional jeweler and founding member and past president of the Creative Metal Arts Guild in Portland, Oregon. Her detailed examination of soldering in Lapidary Journal so far includes: “Solder,” December, 1998; “Flux,” April, 1999; “The Heat Is On,” July, 1999; “Fit and Cleanliness,” September, 1999; and “Solder Joints and Placement,” December, 1999.

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