Solder-Bonded and Soldered-Wire Mokume Gane

Best Practices for Solder Bonded Mokume

After having thoroughly covered eutectic and diffusion-bonded mokume, I now want to include some information for those of you who would like to try solder-bonded mokume. As discussed earlier in this book, there are some inherent problems associated with soldered mokume but, the familiarity of the techniques used to produce it, and minimal prep time, make this technique an attractive way to start.

Below, Alistair McCallum describes the technique that he has used to create many beautiful pieces of mokume:

Solder-Bonded Mokume

The technique that I am going to explain is an adaptation of the traditional technique using hard silver solder. There are many different methods, but this is the one that I favor.

1. Select the metals to be soldered for their compatibility in terms of their malleability and ability to be silver-soldered. These would normally be copper, copper alloys, silver, and gold. I use copper, gilding metal (95 Cu, 5 Zn), and silver.

2. Cut the metal into strips no more than 25 mm wide, ideally around 20mm. The length of the strip is no problem within reason, but for small objects 75mm to 100mm long works well. The shape of the metal should be in narrow strips, this allows the solder to be drawn through the entire width of the strip. Square or rectangular pieces tend to solder around the edges and not in the center. Try to use as thick of a gauge of metal as is available. This will minimize the surface area to be soldered and will expand to a larger sheet when rolled. (I use sheets around 1.5 to 2mm thick.)

3. Flatten and then file the surface of the strip so it is free of oxides, pits, and deep scratches. Then file a bevel on one long edge.

4. Paint the borax onto the filed surface. Put to one side and repeat the process on the second sheet. Once completed, scrub/rub the surface with a paper towel to remove borax. Re-flux and place the two strips together, matching the beveled edges. Use borax paste flux of a creamy consistency.

5. Bind the two sheets together with reasonably heavy binding wire, taking care to evenly space the binding wire loops. It is important to leave a 6mm twisted tail on the binding wire. This will hold the sheets at an angle and make soldering much easier. The binding wire loops and tails are twisted very tightly to hold the metal securely. Solder only 2 sheets together at once, thus minimizing the chance of unsoldered areas. Use hard silver solder all the way through the process. This enables one to use other lower melting temperature solders later. Clean and flux the stick of solder.

6. Heat initially with a large, bushy flame on a revolving turntable until the block reaches a dull red color. At this point, reduce the flame and concentrate the heat on the center of the bound metal. When the correct temperature is reached, stick-feed the solder into the center using the angled V slot as a way of locating the solder. Be generous with the solder.

7. Now spin the turntable and heat from the opposite side to draw the solder through. Spin the turntable again and apply more solder about 15mm in from the left hand edge. Revolve and draw the solder through again till it joins with the center section. Repeat on the right-hand side. Check that the layers are completely soldered together, with an uninterrupted seam of solder showing around the whole perimeter of the metal.

8. Cool, remove binding wire, and pickle. Remove from the pickle and file the excess solder from the surface. Flatten this piece, file and repeat, adding a third metal if desired.

9. Once the strips have been soldered, roll them lengthwise until they have roughly doubled in length. Cut in half and solder the two halves together, doubling the number of layers.

This can be repeated as many times as is necessary. After you have achieved the desired number of layers, this strip may be soldered in the same fashion to a thick, backing material of copper or silver, and forged and then rolled sideways to create the shape and thickness required.
— Allistair McCallum

Soldered-Wire Mokume

Another interesting lamination technique is soldered-wire mokume gane. This is a good first project to try if you like the look of mokume but don’t want to make the investment required by the other techniques outlined in this book. The patterns you can achieve by this method are limited, but striking, and the ease with which you can create this kind of mokume makes this a very useful technique to have in your bag of tricks. Soldered wire mokume is very effective as a border or accent line in a piece of jewelry. Since the wires you will be working with present such a small contact surface area, it is possible to join them without the problems usually associated with solder-bonded mokume. Here is the basic procedure:

“Shield Series” pin by Steve Midgett. Silver, shakudo, copper, and 18K with tanzanite.

Select two contrasting-colored round wires of 12 to 18 gauge, then anneal, pickle, and give them a good rub down with steel wool or a ScotchBrite pad. Crimp one end of the two wires together and clamp them in a bench vise. Fasten the other in the chuck of an electric drill or use Vise-grips. Begin twisting the wires together. The tighter and more extreme the twist, the better it is for this technique. I usually continue to twist until the wire begins to kink or breaks. When finished, the wire should look like a section of tightly twisted rope. Then flux the entire piece and hard-solder the two wires together using as little solder as possible.

Apply solder sparingly, starting at one end, and use the heat of the torch to draw it as far along the wires as you can before adding more. Pickle, clean, and remove any excess solder. The next step is to roll or forge the piece into a square wire. This will compress the rounded forms of the two individual wires into each other and achieve a solid mass with a square cross-section. As you roll, go slowly and turn the metal 90 degrees after each pass. Continue until all the gaps have been closed in and only very small, cold seams remain.

Make sure the wire is free of any oil that it may have picked up from your rolling mill before going on to the next step. Once again, flux the entire piece, making sure the flux penetrates into the minute crevices between the compressed wires. Then, flow hard-solder into these crevices to create a single solid wire. After pickling, remove any excess solder by filing or grinding to expose the pattern. This wire may now be flattened into a strip, rolled sideways into a sheet or cut and re-soldered to form more intricate patterns. When using this type of mokume, use only medium and easy solder to avoid remelting the solder in the laminate.