Mokume Gane is an ancient Japanese material, made up of diffusion welded nonferrous metals. If you've ever heard of pattern welded steel (or "Damascus" steel), mokume gane is very similar, it just is made of metals like copper, brass, shakudo, silver, shibuichi, etc instead of steel. The word itself translates to "wood grain metal" because the final product often has a pattern that looks similar to the grain pattern in lumber. Mokume gane is mainly used for decorative effect, whether it be in jewelry or blade mountings.
Also, this project is being entered in the jewelry contest, please remember to vote if you liked it!
Step 1: Materials and Tools
You will need the following materials and tools to make the billet:
*Two types of nonferrous metals that have welding affinity with each other. I used 1/8"×2"×1.5" copper and brass
*2 1/4" thick steel plates that are slightly longer and wider than your nonferrous stock.
*2 bolts with washers and nuts
*Section of rebar
*Flux, I use borax
*Welder, technically this can be worked around, but it helps a lot
*Forge capable of achieving welding heats for whatever type of metal you are using. For brass and copper, you need around 1800° F
*Drill bit that is the same diameter as the bolts
You will need the following materials for shaping the billet:
*belt sander (optional)
*buffing wheel (optional, for polishing)
*Polishing paste (also optional, I use flitz)
Step 2: Prepping the Billet
I start by marking two 2" sections of my copper stock. I then take it to the vice and cut those sections off with a hacksaw. After that, I mark out the same amount of material on an antique brass doorstop I have, and cut that section out with a hacksaw. The sides of the brass pieces weren't quite flat (they had a little curved ridge in them), so I hammered them completely flat. At this point, all faces of each piece should be sanded so that no oxidation remains. This is very important! Any oxidation that is left can cause inclusions or failed welds in the final product. Once you have sanded them, wash them with soap and hot water to remove all dirt and oils from the surface. After this is done, set them down to dry, and try not to touch the metal with your bare hands from this point onward.
Step 3: Steel Pressure Plates
Mark your steel stock so that it is about 1.5" longer than your copper stock. In this case, mine was about 3.5". Cut out two plates like this. Now take these plates and drill 4 holes through the ends. This is where the bolts will fit through the plates. Stack the nonferrous metal plates in between the steel plates, alternating the type of metal (copper, brass, copper, brass). Screw the steel plates together over the billet and tighten them as far as they will go. The billet inside should not be able to move or shift around after this is done. In order to make the whole thing easier to hold and move around, I tacked on a rebar handle with a welder.
Step 4: Diffusion Welding
Take your billet and put it into the forge. Let it come up to red heat and then take it out and liberally sprinkle your flux over the material. Put it back in the forge, and let it come up to welding temperature. You will know when your billet is ready to weld, because the material will start to sweat. It's really hard to explain this concept if you've never seen it in person before, but basically the material in the billet will start to look shiny and almost liquid, and you may start to get beads of material forming along the edges. At this point, take the billet out. I left it in for just a second too long on my first weld, and the corners of my brass stock ended melting out a little. Anyway, once you take the billet out, take it to your anvil and make several medium strength strikes with a hammer on the top of the pressure plates. This will weld the billet together and allow you to be able to remove it from the pressure plates without it falling apart.
I picked up the billet with the tongs and sprinkled some more flux on. Then it's back in the forge. Once it comes back to welding heat, I hammer it once again (this time out of the pressure plates) to make sure I get a good weld across all the material.
I wanted more than 4 layers in my billet, so I folded it on my hot cut, and ended up setting another weld. This part isn't necessary, but it will double your layer count every time you fold it, giving me 8 total layers in the end.
After I've made all the welds, I turn off the forge and let the billet cool. Then I used the belt sander to check my welds and layers. I had to grind pretty far in to get rid of some inclusions on the outside, but the welds closer to the center look really good. I did lose some brass to melting, but there is still a lot of it left so I'm pretty happy with what I have right now.
Step 5: Designing
My billet was really thick after welding, so I drew it out, down to a little over 1/8" thick. I did this all with cold forging and a square hammer, just make sure to anneal (heat to dull red and quench) your metal every little while to avoid stress fractures.
Once I worked it down to where I wanted it, I started drafting out a design. The design phase is very important with mokume gane, because you have to create a shape that will reveal the different layers of metal. I decided on a triangular shape with 3 bevels in it. Since my billet right now is just a simple stack of alternating metals, grinding in bevels will leave a "contour map" of those alternating metals.
Some other patterns you can do are:
1) Raindrop: drill halfway through the billet with a masonry bit in a couple places, then hammer the billet flat again. This will leave a bunch of bullseye looking circles in your material
2) Organic raindrop: Same thing as before except, instead of using a masonry bit, use a spherical grinding bit on a dremel to grind halfway through the billet slightly erratically. This will leave a very organic random pattern
3) Twist: if your billet is in a square or round shape, you can twist it and then take cross sections of the twisted rod, this gives you a warped star-like or diamond pattern
4) Ladder: One of my personal favorites. If you take a round or half round file and file in a bunch of parallel lines down your material then hammer it back flat, it will leave a ladder-like pattern composed of a bunch of really wide ellipses.
There are tons more patterns out there, if you are interested in other patterns or want a more in depth description of one I mentioned, feel free to ask, I'll be glad to help.
Step 6: Grinding and Shaping
I start by clamping the piece in my vice, then I cut straight down the line with a hacksaw. A hacksaw isn't able to cut tight curves, so I switched to a jewelers saw to finish the cut. I quickly file the corner of the end of the tail, and then cold forge it straight to make a perfect triangle. After this, I mark my three geometry lines with a sharpie and start to file out the shape. The picture shows me holding the piece while I was filing it, but I couldn't get a good enough grip on it so I ended up moving it to the vice for filing.
After the filing was done, I took out the rough file marks with a 150 grit belt on a belt sander. This also helped to straighten and sharpen each geometry line.
Step 7: Polishing
Starting at 200 grit, I hand sand each of the 3 faces of the triangle, going all the way up to 2000 grit. Make sure you don't roll the geometry lines, they should be very crisp. Alternate the direction you sand every time you move up a grit. Once you've gotten it worked up to 2000, take it inside and wash off all the dust, dirt, and oils. At this point, I use a polishing compound called flitz to get a mirror finish. Just dab a very tiny amount of the compound onto a dry cloth, buff the material you want to polish, and rinse off the residue. You can also use a buffing wheel and buffing compounds to finish the metal, but I find that buffing wheels tend to roll and dull the geometry lines.
Step 8: Loop for a Chain
I needed to add a place for the pendant to hang from a chain, so I ended up just bending the top part of the triangle into a loop. I didn't want to scratch up the polish, so I wrapped my needle nose pliers with some electrical tape before I did the bending.
I ended up using some dark brown leather for the necklace chain, but you can use just about anything.
Step 9: Patination
Mokume Gane is traditionally patinated (or oxidized) to bring out the differences in the two metals. It is traditionally patinated in a solution called niage, which is a combination of cupric sulfide and rokusho that is heated up before the metal is etched. This normally produces very good contrast, but the brass I used was too similar to the copper here and I didn't get as good contrast as I would have liked (see picture 3). It can also be hard to get your hands on niage, so I will also be explaining some other patination methods that are much more available to most people.
1) Salt and Vinegar: Probably the most common, this solution is basically just salt, vinegar, and water. There is no "correct" ratio of salt to vinegar, you'll just have to experiment to find what you like best
2) Aging: this is the simplest method, and is what I have shown in the pictures above. Just clean the metal, rub it with your fingers, and leave it open to the air for a couple days. The oils and salts from your hands combined with the oxygen from the air will significantly darken the copper, but leave the brass mostly unchanged because of its zinc content.
3) Liver of Sulfur: This is used by jewelers a lot, and provides a very even, VERY dark finish
4) Overboiled Eggs: boil an egg or two for way longer than you normally would. This will convert a lot of the yolk into a sulfuric compound. Take out the yolk and crush it up then put it in the bottom of a jar. Suspend the piece you want to patinate over the egg, then seal the top of the jar with some saran wrap. This will leave a very rustic, dark, uneven finish.
Quick note: For all these methods, it is completely necessary that ALL of the oils and dirts have been washed off the surface of the metal prior to patination. Any oils that are left will create a patch of metal that doesn't oxidize, ruining your patina.
Step 10: Finished
Thanks for reading, I hope you enjoyed. Don't forget to vote if you liked it :)
Let me know what you all want to see in a future instructable in the comments section! It really helps me to know what you all are interested in seeing next! If you have any questions or comments, don't hesitate to post them in the comments section. I can also be reached at YozakuraForge@gmail.com if you would like to email me directly.
Interested in seeing more of my work? Check out my profile Saxman25 on BladeForums, this is where I put most of my knives and woodworkings up for display or for sale.