Tips and Techniques

Care of Mokume-gane
Mokume-gane is made by welding together sheets of sterling silver and copper alloys producing a single multi-layered billit, which is then manipulated to produce striking patterns and designs. Because the pattern is in the metal, it cannot wear off.

The metals used are chosen to have the greatest possible contrast in color. This contrast is enhanced by the patination or darkening of the copper or copper base alloys. For most people, the patination is self regenerating, but in some cases the patina will wear off, leaving bright copper. If repatination is desired, rub the item with a mixture of very mild ammonia and salt or with Baldwin's Patina, available from Reactive Metals Studio at 1-800-876-3434.

Knifemaker's Mokume-gane
Technical Information for Nickel Silver/Bronze Mokume-gane (NS/Br)
Shining Wave Metals, a commercial producer of mokume-gane since 1984, now offers a line of this material that specifically meets the needs of knifemakers. The Knifemaker's Line is composed of nickel-silver and a red bronze to meet the maker's need for a mokume with a combination of a bold pattern, high strength, good formability and good machinabilty.

Note: Nickle Silver/ Bronze Mokume (NS/Br) contains the metal nickel, known to cause cancer in laboratory animals. Some indiviguals may experience allergic reactions in the form of rashes or other irritation. Avoid inhaling the dust while working the metal. A high degree of skin contact is not recommended. This product may not be used for jewelry in the European Economic Community (EEC).

Forging
This mokume -gane will work similarly to nickel-silver. It may be cold forged, with a 30% reduction between annealing. This material may be hot forged, but doing so will void the warranty. Start hot forging at about 1400°, a medium red, and stop at a black heat. Be sure to avoid heat fatigue by working the metal sufficiently during each heat.

Machining
This material machines differently than leaded brass, the standard for copper base metals. Most bronzes are somewhat mushy and grabby on the tools, if difficulty is encountered machining Knifemaker's Mokume, try the following:

1. Use only very sharp tools. Dull tools will tend to smear the metals rather than cut them. If using a lathe type bit, use a knifelike positive rake, about 15 degrees with a rounded end. I use tungsten base, high speed steel, micro crystal carbide works well too.
2. Tool speed should be fairly fast, with a slow feed. Fast feed makes for a greater chance of the tool getting stuck. Slow tool speeds tend to make for a poor finish.
3. Use either an aluminum type cutting fluid, or a wax-based lubricant. Water based cutting fluids don't seem to work well. Dry cuts will work, but feed must be fairly slow.

The first factor is the most important. In drilling heterogeneous materials it must be noted that breakage is a problem, this characteristic is used in safe construction. If the drills are sharp, (TiN coated drills work the best) with a high speed, light feed and good cutting fluid, this material will drill easily. A dull drill is indicated if high pressure is needed to make it cut.

Sanding & Polishing
NS/Br may be machined, ground, sanded and polished similarly to nickel-silver or brass. Care should be taken in grinding and buffing not to smear the surface of the metal as this will show in the pattern. Lea compound may be used in place of sanding belts for finishing grinds. To bring to a high polish, sand to 600 grit and then buff with "White Diamond" buffing compound on a muslin wheel. Be sure to wear a dust mask during any sanding and polishing operations.

Thermal Operations
Anneal this metal at 1250ºF to 1350ºF (675ºC to 732ºC) and quench. Pickle to remove heat scale using a jewelers pickle or white vinegar. Avoid soaking the metal at the annealing temperature for more than 15 minutes. NS/Br may be both soft and hard soldered without difficulty using any method. Do not braze with rod that melts above 1,600ºF (870ºC). TIG welding is not recommended. Be sure to use adequate ventilation for all heating operations.

Etching
NS/Br may be etched using several acids; however, a ferric chloride solution is recommended. If deep etching, clean all surfaces during the etch by brushing to remove residue. More dilute solutions give a cleaner etch, we recommend a dilution that looks like weak coffee. The nickel silver will etch high. Be careful not to over etch. Neutralize the etchant with a sodium bicarbonate solution after the desired depth is reached. Observe standard precautions for using acids.

Post Etch Surface Treatment
To enhance the pattern after etching, power brush with a very fine stainless brush and/or buff lightly with a soft wheel and a stainless buffing compound. Clean off residual compound with either acetone or a citrus cleaner. Large numbers of parts may be tumbled with a very fine plastic media or steel shot. Various patinas may be used to enhance the pattern. Be sure the surface is very clean before applying patina solutions. A patina that gives the same colors are extensive handling is Baldwin's Patina available from Reactive Metals Studio, 800-876-3434. Liver of sulfur or calcium polysulfide (available in garden supply stores) will darken the bronze. Commercial brass black or steel bluing solutions containing selenium will darken both the bronze and the nickel silver. Patina is worth experimenting with, try it!!

For technical support call or FAX Shining Wave Metals at 425-334-5569.