Tutorial: Copper and Sterling Silver Mokume-Gane Earrings By Hadar Jacobson

OLYMPUS DIGITAL CAMERAMokume-gane (a Japanese word meaning wood-grained metal) is a difficult mixed-metals technique that originated in 17th-century Japan. Different colors of metals and/or alloys are stacked and diffusion-bonded into a single billet that is carved and forged alternately to expose the different metal layers, creating unique and detailed patterns resembling wood grain. Creating true mokume-gane is an arduous and time-consuming process that requires a great deal of technical skill and experience.

Polymer clay artists use simple techniques to produce patterns that loosely mimic the look of true mokume gane, but they are not practical to use for combining multiple types of metal clay. Artist, teacher and author Hadar Jacobson shows MCAM readers her own method for simulating mokume-gane with silver and copper metal clays.

Project Materials and Supplies

Materials
20 g low-shrinkage silver clay
1.5 g Hadar’s Clay™ Quick-fire Copper
4″ (102mm) length of 22 ga. wire, fine silver or Argentium® silver
Pair of silver earring wires

Tools & Supplies
Basic Metal Clay Set-Up List
Coffee grinder (dedicated for silver clay use only)
Clay extruder
Extruder disc with a large round hole
20mm x XXmm rectangular cutter
Extra-fine mini fiber wheel for rotary tool or #0000 steel wool
Rubber or nitrile gloves
Sponge- or cotton-tipped swabs
Baldwin’s Patina

Project Step-By-Step

Step 1

Prepare the sterling and copper clays Prepare a batch of sterling silver clay  and a batch of copper clay (Another source if mixing your metal clay from a powder is new:

If mixing your own metal clay from power is new for you, please see notes at the end of this project.

Step 2

Roll and cut the copper and sterling clay circles. Roll out the copper clay 1.5mm [6 cards] thick. Remove the disc and/or cap from the extruder, if necessary, and apply a thin film of olive oil (or other clay release agent) to the inside and outside of the open end. Using the open end of the extruder as a circle cutter, cut out four copper clay circles. Cover them with plastic wrap while you repeat the process with the sterling silver clay, except roll the sterling clay to only .75mm [3 cards] thick before cutting out the four circles [1].

Step 3

Stack and extrude the clay. Stack the clay circles in alternating layers of copper and silver [2]. Apply a thin film of olive oil to the inside of the extruder barrel and slide in the clay stackit. Use the large round-holed disc to extrude the cane into a clay rod approximately 4″ [102mm] long [3].

Step 4

Cut the cane into eight equal lengths. Measure the length of the cane, find the center point and cut the cane into two shorter pieces of equal length [4]. Repeat this process with both halves of the cane, creating four equal segments. Cut each of those four pieces in half so that you have eight cane segments of equal length.

Step 5

Stack and roll the segments into a single, thick cane. Stack the cane segments vertically and press them together to form a thick bundle, as shown from the top in photo [5]. Place the bundle lengthwise on your work surface and roll it back and forth with your fingers, compressing the cane segments together to form a single, very thick cane [6]. If the cane lengthens, compress it from both ends towards the center to bring it back to its original length.

Step 6

Slice and shape the cane. If the cane is too soft to slice cleanly without distortion, stiffen it in the refrigerator. Slice the cane in half crosswise [7] and separate the two halves, revealing the cross-section pattern. Place the slices cut side up and form them into two matching shapes as desired, leaving the fronts and backs flat [8]. Let the pieces dry.

Step 7

STEP 7: Sand and drill the earring drops. Sand the front and back of each shape with 400-grit sandpaper or sanding sponge until the entire pattern is crisp and clear [9]. Drill a hole lengthwise through the center of each earring drop with a small hand drill [10].

Step 8

STEP 8: Fire the earring drops. I highly recommended making and testing some sample pieces to determine the optimal target temperature for your kiln and firing container (see note at end of article). Then fire the earring drops according to the two-phase firing directions in the Instruction Manual for Hadar’s Clay™ (http://artinsilver.com/Quick-fire_clay_instruction_manual.pdf), adjusting the phase two temperature based on your test results.

Step 9

STEP 9: Finish the metal. The fired copper will have a surface layer of dark oxidation (see the left-hand earring drop in photo [11]). Sand with 220-grit abrasive to remove the oxidation and then switch to 400-grit abrasive, stroking at right angles to the coarser-grit marks until they disappear. Create a matte finish (see the right-hand drop in photo [11]) by using a rotary tool with an extra-fine mini fiber wheel attachment or by rubbing the metal gently with #0000 steel wool.

Step 10

STEP 10: Apply the patina. Unlike liver of sulfur, Baldwin’s Patina reacts with copper but not silver and will increase the contrast between them. Wearing rubber or nitrile gloves, use a drop of the solution on the end of a sponge- or cotton-tipped swab to apply the patina to the patterned areas. (Use very little of the solution to avoid turning the copper green.) The copper will turn a dark, rich brown very quickly, creating a dramatic contrast against the silver [12]. As soon as this happens, rinse the pieces in warm water and dry them.

Step 11

STEP: 11: Make the ball-end headpins. Cut two equal lengths of fine silver or Argentium® silver wire approximately 2” long. (You may need a bit more or less wire depending on the length of your beads.) Grasp one end of a wire with pliers, at right angles to the jaws, and turn the pliers so that the wire hangs straight down in a vertical position. Turn on the butane torch and raise the wire (still held in the pliers) just above the torch flame. Slowly lower the very bottom of the wire until it is in the edge of the flame directly above the pointed tip of the blue cone. The wire end should begin to ball up very quickly. Pull the wire out of the flame as soon as the ball is larger than the bead holes [13]. Ball the end of the other wire, keeping a close eye on the ball size so that the headpins match.

Step 12

Assemble the earrings. Thread each wire through the bottom hole of an earring drop. Make a wrapped loop at the top and trim the excess wire. Hang the drops on the ear wires [14].

Step 13

Variations: To make cabochons press the cane slices into lightly oiled shallow concave molds (such as the wells of a plastic paint palette).

Mixing the Sterling Silver Clay

Since the two clays may contain different amounts of water, it is best to weigh them in the powder form. Dry 20 grams of low-shrinkage silver clay and grind it in a dedicated coffee grinder. To make 20 grams of sterling silver clay, mix 18.5 grams of silver powder with 1.5 grams of Hadar’s Quick-fire Copper powder. Prepare the clay with water according to the mixing instructions in the Instruction Manual for Hadar’s Clay™ or the video tutorial .

Making, Firing and Testing Sample Pieces

Roll and cut slabs of copper clay 2 cards (.5mm) thick. Use a blade or a commercial cutter to cut a rectangle 20mm long and approximately 10mm wide from each slab. Stack the rectangles and roll them up together tightly like a jelly roll. Cut the roll into slices .5mm] thick and dry them thoroughly. Fill any gaps with more clay. Fire according to the suggested two-phase firing schedule for Hadar’s Clay™ Quick-fire Copper in the Hadar’s Clay™ instruction manual, except begin the second firing phase at only 1325°F [718°C] in a front-loader muffle kiln or 1250°F [677°C] in a top-loader brick kiln. Test the fired samples to determine whether they sintered fully. Make, fire and test another batch of unfired samples, raising the second-phase firing temperature by 10°F to 15°F (-12°C to -9°C). Repeat as many times as needed until you reach the optimal sintering temperature in your particular kiln and firing container.

About the Author

Hadar Jacobson has been a metal clay artist and instructor for the past 15 years. She is the author of three books about metal clay, the first of which is now in its second edition. Her fourth book, which is about patterns of color in metal clay, will be published soon. She also manufactures copper, bronze, white bronze, and steel clays in powder form under the Hadar’s Clay™ brand. You can see her work on her web site at artinsilver.com and read her base metal clay tutorials on her blog at www.artinsilver.com/blog.

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