Most concentrated acids are highly corrosive by skin and ingestion. They cause severe stomach damage, and ingestion of one-eighth of a cup or less may be fatal. Diluted acids are less hazardous. Acid vapors from nitric, sulfuric, hydrochloric, and hydrofluoric acids are highly irritating to the respiratory system, and inhalation of large amounts might cause pulmonary edema.
Where gloves and goggles when handling concentrated acids. When diluting , always add the acid to water, never the reverse. In cases of spills on the skin , wash with lots of water; in case of eye contact, rinse with water for at least 15 minutes and call a doctor. In case of ingestion, do not induce vomiting; call a doctor.
1. Most alkalis are highly corrosive to the skin and eyes. Ammonia is particularly hazardous to the eyes.
2. Ingestion of small amounts can cause severe pain and damage to the mouth and esophagus and can be fatal.
3. Inhalation of alkali dusts can cause pulmonary edema.
4. Dilute alkaline solutions are more irritating to the skin and eyes than dilute acid solutions.
1. Wear gloves and goggles when handling alkaline powders and solutions.
2.In cases of spills, wash with lots of water; in case of eye contact, rinse with water for at least 15 minutes and call a doctor.
3. Do not induce vomiting if ingested.
A. Metal must be absolutely free of dirt, oxides, and oils. . Scrub with wet purple Scotch-Brite & pumice to expose bare metal. Rinse in clean water. Check with the water break test for freedom from dirt and oils, and blow dry or pat dry with clean lint-free paper towel or cloth. It has been my experience that most failures in lamination occur due to improper cleaning and oxide removal. Rinse metal thoroughly in clean running water after acid bath, then dry immediately. I get my best results when I dry the metal with clean, dry air from a vacuum cleaner blower that has never been used for anything but this purpose. It is impossible to remove all of the dirt from the blower if it has been used as a vacuum cleaner and this will be deposited on your carefully cleaned metal.
B. Paint the faces of the torque-plates1 that will come in contact with the laminate with yellow ochre or Scalex and allow to dry. This will prevent the billet laminating to the torque-plates. Stack metals between torque-plates and tighten bolts. Place in vise or hydraulic press, compress stack as much as possible and then tighten bolts again.
C. To keep out oxygen during the firing of the stack you will make a metal box or bag put
the stack in it with some charcoal to reduce any oxygen around the billet. Use strips of thin sheet steel (>28 ga.) to make a box of the torque-plates. Or make a bag from stainless steel foil tool wrap and place the stack in it see appendix A. Fill the space between the plates with granular charcoal. It is important to pack the charcoal firmly so there is little room for air in the box, and secure edges of box with binding wire as shown below. If you use the tool wrap seal the charcoal around the billet by using masking tape to form a box around the perimeter of the plates.
D. Fire the box in a preheated kiln at 50°-100 ° F below the lowest melting point alloy in the stack (this is where it is important to know the exact temperature in the kiln). Heat soak for 3-12 hours. Copper and gold alloys bond at 1350 ° - 1800 ° F; silver and high-silver alloys bond at 1300 ° -1400 ° F.
E. Remove stack from kiln. Remove billet from torque-plates and forge while still hot. Use torch to keep billet at forging temperature. Billets with silver must be forged at a black heat (no red glow = max of 900°F), nickel alloys may delaminate if not forged before being allowed to cool.
F. Cool billet and saw off the edges. Remove 1/8"-1/4" from each edge; this reduces the possibility of stress cracking during forging and rolling.
G. Forge or roll billet to working thickness. A reduction of 50% or more is a good idea. If you have access to a rolling mill that will handle thick material then you can roll at this stage.
H. Start pattern development or roll down until billet is ready for ?relamination.
I. Develop the pattern with burrs drills files, punches, chisels, or mills.
J. Anneal often when rolling down to keep from delaminating billet. Roll until the sheet is at the desired thickness.
Do not place in contact with silver or high-silver alloys as it will melt (it makes silver solder).
Fine Silver
1760
Sterling Silver
1640
Gold (24K)
1945
almost all gold alloys will work. 14K yellow should be fired at 1350°
Shakudo
1922
95% Cu, %5 Au
Shibuichi
1742
75% Cu, 25% Ag
Kuromi-do
1958
99% Cu, 1% As (This alloy is not safe to make in the studio due to arsenic content.)
Copper
1981
Oxygen-free alloy is best.
Yellow Brass
1749
70% Cu, 30% Zn
Nu- Gold
1700
A Copper Zinc alloy (Jewelers Bronze)
Nickel silver
2030
65% Cu, 18%Ni, 17%Zn. Anneal often Do not quench
Some thought should be given to the hot and cold working characteristics of the alloys in the stack so that they will match the processes you intend to use on the laminate. Helpful references are melting-point graphs, phase-change diagrams, and working characteristics found in metallurgical texts.
?There are two basic methods of pattern development: One is carving into the surface with burrs, chisels, gravers or mills (round-shaped tools expose the most area of each layer when cutting), then forging the billet or rolling it down to expose the pattern. Try not to cut more than 1/2 the thickness of the billet or you may end up with holes in the sheet during final rolling. The carving and forging/ rolling steps are repeated to develop the pattern. The other method is setting the metal in a medium like pitch or soft wood and raising bumps on the surface as in repoussé. The resulting bumps are filed off and sanded. Take care that none of the bumps are deeper than 1/2 the thickness of the sheet or a hole will be formed when it is filed down.?
When using the cutting or chiseling method of exposing the under layers there are ridges left on the surface of the metal that have a tendency to mushroom over when the billet is run through the rolling mill to smooth the surface. They will end up as thin flakes or foil that is flush with the surface, they will peel up and leave pits in the surface if they are not removed by the use of sand paper, bead blasting, or file. The best method of locating them is to use the bead blasting as it will cause them to lift up from the surface for removal, a stiff wire brush can also be used to locate them. A good test to see if you have removed all of them is to apply a piece of cellophane tape to the surface and then peel it up; it will lift the foil and flakes up.
Cupric acetate- 6 grams
Copper sulfate- 1.5 grams
Table salt- 1.5 grams
Distilled water- 1 liter.
The formula and procedure come from ""Research Presentations to the Society of North American Goldsmiths: 1977-1980", Metalsmith Papers Of the Society of North American Goldsmiths "
? The torque-plates are made from steel that is 1/2" thick. They should be cut large enough to allow for bolt holes to be drilled around the perimeter, and still allow room for the stack in between the bolts. It may be made of mild steel or stainless steel. Thinner (less than 3/4") mild steel will deform in the high temperature of the kiln and it will not apply even pressure after being used once. Torque-plates made from 304, 310 or 316 stainless steel will last for a longer time without deforming. The bolts should be 1/2" in diameter. If you use thicker plates (1") they can be ground flat with a surface or Blanchard grinder. This can be expensive unless you have several plates as most grinding businesses have a minimum charge of about $50. New Stainless Steel plates, bolts, and nuts should be placed in a kiln at 1500° for one hour, then allowed to cool slowly. This builds up an oxide coating, which will keep them from bonding to each other during firing of the billet.
VII. BIBLIOGRAPHY
"Research Presentations to the Society of North American Goldsmiths: 1977-1980",
Metalsmith Papers of the Society of North American Goldsmiths,
Society of North American Goldsmiths, Book Dept., 513 Everett St., Wichita, KS 67213
"Jewelry Concepts and Technology", Oppi Untracht, 1982,
Doubleday & Co., Inc., Garden City, NY
"Studio Mokume", William Ard,
Metalsmith, Winter 1981
"Mokume Meltdown at Carbondale", Stephen A. Walker,
Metalsmith, Spring 1983
"The Complete Metalsmith" Tim McCreight,
Davis Publications, Inc., Worchester, MA.
"The Colouring, Bronzing And Patination Of Metals", Richard Hughes and Michael Rowe, Crafts Council, 11/12 Waterloo Place, London, SW1Y 4AU, England
I. Equipment.
A. An electric kiln with a good temperature control system (accurate to within 5°F)
B. Anvil or other surface to forge on.
C. A 3"-4" vise. (Insure the bolts of your torque-plate will not interfere with the jaws being flat against the torque-plate's surface)
D. Torque-Plates and nuts and bolts. (see page six of handout)
E. Rolling mill.
F. 1 lb. or larger forging hammer.
H. wrenches for torque-plate bolts.
I. Tongs to handle hot torque-plates and billet while forging
II. Supplies.
A. Ground charcoal (briquettes crushed with a hammer will do nicely)
B. 30ga sheet steel & 22 ga. binding wire for box (hardware store )
C. Stainless steel tool wrap also known as heat treating foil (Machine tool supply house)
D. Purple Scotch-Brite pads (jewelers supply, hardware store)
E. Pumice (jewelers supply, hardware store)
F. Scalex or Yellow ocher (jewelers supply, hardware store)
Tool wrap is used by heat treaters to make bags that are air tight to protect air-hardening steels from oxidation during heat treatment. It makes an excellent barrier to oxygen during Mokume lamination. To make a bag cut the foil with scissors to be 2" longer than the perimeter of the torque plates (4"x4"=16"+2"=18") and about 12"wide. Fold the foil in half along the 18"side and make a double fold at the edges. Use a burnisher or roller to flatten the double fold seam. Make a tube out of the seamed foil and then Double fold the bottom end of the tube to form a bag. Use a rawhide mallet to flatten the bottom double fold. Insert the torque-plates and some charcoal and seal the top of the bag with a double fold. It can now go into the kiln.
