Making Mokume

[cliffrat]

I am trying to make Mokume using semi-precious metals and I am having trouble finding out what temps to fire the stack at. I am working with brass, Ni-Silver, copper, and iron. I sand the faces down to 320, acetone bath, stack in stainless foil wrap between two 3/8 inch pressure plates, press it, bolt it tight and fire at 750 degress for 3 hours. The Nickle-silver isn't bonding. Does anyone have any tips or tricks to make it work? Am I not firing at high enough heat?

[MattBower]

I am trying to make Mokume using semi-precious metals and I am having trouble finding out what temps to fire the stack at. I am working with brass, Ni-Silver, copper, and iron. I sand the faces down to 320, acetone bath, stack in stainless foil wrap between two 3/8 inch pressure plates, press it, bolt it tight and fire at 750 degress for 3 hours. The Nickle-silver isn't bonding. Does anyone have any tips or tricks to make it work? Am I not firing at high enough heat?

Is that 750 F or 750 C? If it's 750 F, that's not nearly hot enough. 750 C almost certainly isn't hot enough, either, although it's [maybe it is for what you're doing, in which case you might just need more time under pressure] getting closer for the brass and nickel silver.

I've only made very simple mokume, and in my case I simply put the billet in a very hot forge and watched the billet until it started to "sweat." And I've never used nearly as many different materials are you're trying to use in one billet Both the foil wrap and the multiple metals of different melting points complicate things considerably.

[MattBower]

Is that 750 F or 750 C? If it's 750 F, that's not nearly hot enough. 750 C almost certainly isn't hot enough, either, although it's getting closer for the brass and nickel silver.

I've only made very simple mokume, and in my case I simply put the billet in a very hot forge and watched the billet until it started to "sweat." And I've never used nearly as many different materials are you're trying to use in one billet Both the foil wrap and the multiple metals of different melting points complicate things considerably.

OK, I see you're trying to use a different process than the one I'm familiar with. I can't help you with that. Good luck!

[cliffrat]

OK, I see you're trying to use a different process than the one I'm familiar with. I can't help you with that. Good luck!

I am not combining all of those materials in one billet, although those are the materials I am using. I use the foil wrap to limit the oxidation between materials (I wrap the billet in combustables like paper before I wrap in the stainless sheet)I tried firing at 750F because that was what I was told was the temp that the brass needed to fuse. The brass fuses fine to the copper, but it wont fuse to the Ni-Si.

What process do you use?

[cliffrat]

OK, I see you're trying to use a different process than the one I'm familiar with. I can't help you with that. Good luck!

When I tried the "put it in a hot forge" method, everything sort of melted away and made a mess. So I am using my Paragon oven now.

[clinton]

I saw Mark Constable make mokume in a coal forge using a hydraulic press after heating the billet, he did say that it took lots of trial and error, he was using copper and brass if I remember right

[MattBower]

I'm glad you're not trying to use all that stuff in the same billet! That's a bit of a relief.

I'm surprised that 750 F will bond the brass, but much of metallurgy seems to come down to time and temperature. So in the case of the brass I guess it's the three hours that makes the difference. On that same note, if you're not getting fusion, my guess would be that you need to increase either the time or the temp, or choose different metals. As far as what's an appropriate temperature, I can't give you specific recommendations. In your place I'd start maybe 100-200 degrees lower than the lowest melting metal in the stack, and experiment from there as far as time. If no reasonable soak time gets you a bond, maybe bump the temp up a little. But I've read that some metals really aren't compatible in mokume, so don't be surprised if you can't find an appropriate time/temp combination for certain combinations of metals. I'd try to stick to stuff with similar melting points within a single stack.

Are you using any kind of press to ensure intimate contact between the plates in the stack, or are you using only the torque plates?

The "put it in a hot forge" method definitely requires close attention. The moment it looks sweaty, it's time to pull the billet out. But it's a different process. In that case you're essentially brazing the stack together.

[Frosty]

Mokume gane doesn't involve fusion at all, the process is diffusion. This means the atoms in adjoining metals begin to exchange electrons and the atoms form alloy molecules making a joint as strong as the weakest material.

You can do it cold if you aren't careful. some of Father's machinist tools included "Joe blocks" they're steel blocks of certified dimension used to check mics, calipers or other measuring instruments. They're accurate to within a fraction of a 10,000th" and polished. If they got stacked or otherwise touched face to face they'd be diffusion welded into a single block within a few hours to days depending on how clean they were. a layer of oil only helped the process.

Unless you're going to be trying to bond some exotics don't over complicate things. Brass and copper make easy peasy mokume billets, shine em up, clean with a clean drying solvent, stack in a clamp and heat to bright red for a while. Done deal.

Silver and copper are another nearly unscrewupable combination and you can forget the SS foil and such. Clean, stack, clamp and heat.

Do NOT put brass and silver in contact you'll get a eutectic reaction and make silver solder that'll just flow out of the clamp at a really low temp.

For practice try stacking a few US quarters, heat to a bright red and do a little hammering to firm up the diffusion weld. A little borax won't hurt but isn't really necessary. Quarter mokume is good practice and is reasonably inexpensive. It's a really good way to learn to judge heat by colors and recognize "sweating" heat.
Have fun, play safe and post pics.

Frosty the Lucky.

[MattBower]

Frosty, you're right that I was sloppy with my terminology -- I tend to do that, since I have trouble keeping fusion and diffusion straight -- but I believe quarter mokume actually is a fusion process. The copper goes liquid and gets drawn by capillary action between the layers of nickel. At least that's what it looks like when I do it. And that seems to make sense, given that nickel doesn't like to bond to nickel in the solid state.

[pkrankow]

Frosty, you're right that I was sloppy with my terminology -- I tend to do that, since I have trouble keeping fusion and diffusion straight -- but I believe quarter mokume actually is a fusion process. The copper goes liquid and gets drawn by capillary action between the layers of nickel. At least that's what it looks like when I do it. And that seems to make sense, given that nickel doesn't like to bond to nickel in the solid state.

Do remember that the silver layer of a quarter is a copper/nickel alloy to start with. It is similar to the entire composition of a modern nickel.

I would say it takes a sloppy job to get the red metal between the layers of silver metal.

This is US money I am talking about. $3 in quarters can be more fun than you may think $3 is supposed to be!

Phil

[MattBower]

Good point, Phil. I still think it's brazing, though.

[pkrankow]

Good point, Phil. I still think it's brazing, though.

I definitely had something softer than solid on every try when I made quarters mokume. The first try I had a puddle!

My wife wants a butterfly necklace out a piece of the billet I have left to go with the heart I made for her.

Phil

[cliffrat]

Mokume gane doesn't involve fusion at all, the process is difusion. This means the atoms in ajoining metals begin to exchange electrons and the atoms form alloy molecules making a joint as strong as the weakest material.

You can do it cold if you aren't careful. some of Father's machinist tools included "Joe blocks" they're steel blocks of certified dimension used to check mics, calipers or other measuring instruments. They're accurate to within a fraction of a 10,000th" and polished. If they got stacked or otherwise touched face to face they'd be difussion welded into a single block within a few hours to days depending on how clean they were. a layer of oil only helped the process.

Unless you're going to be trying to bond some exotics don't over complicate things. Brass and copper make easy peasy mokume billets, shine em up, clean with a clean drying solvent, stack in a clamp and heat to bright red for a while. Done deal.

Silver and copper are another nearly unscrewupable combination and you can forget the SS foil and such. Clean, stack, clamp and heat.

Do NOT put brass and silver in contact you'll get a eutectic reaction and make silver solder that'll just flow out of the clamp at a really low temp.

For practice try stacking a few US quarters, heat to a bright red and do a little hammering to firm up the difussion weld. A little borax won't hurt but isn't really necessary. Quarter mokume is good practice and is reasonably inexpensive. It's a really good way to learn to judge heat by colors and recognize "sweating" heat.
Have fun, play safe and post pics.

Frosty the Lucky.

Ok so it looks like I have had some sort of success here with the 3 color/metal combination of brass/copper/nickel-silver. Thanks to all you guys for the words of wisdom & advice. Here's the process I used:
1. cut stips of .064 material into strips about 1 inch wide and 6 inches long.
2. Clean them up to 220 grit, acetone bath and stack.
3. Wrap them in SS foli with some plain old paper.
4. Press the whole mess together between 2 3/8 inch steel plates with bolts through the corners in my 2 ton bottle jack press and tighten the bolts.
5. Into the Paragon oven at 1500 F for 2 hours.
6. Let cool until safe to handle.
I just took this apart and cut the ends off. It's about 11/16 inches thick.
Tomorrow I will try to forge it into a poor-man's ladder pattern.
Any Ideas on how hot to go with that?

Check the pics.

[pkrankow]

Try annealing at about 1000F, or better still look up the anneal temperatures of the three materials and use the highest temperature. It is annealed right now since all three of you metals do not quench harden.

Or do you want to work this hot?

Phil

[cliffrat]

Try annealing at about 1000F, or better still look up the anneal temperatures of the three materials and use the highest temperature. It is annealed right now since all three of you metals do not quench harden.

Or do you want to work this hot?

Phil

Well I need to forge it down to some pretty thin stock for jewelry, so I need to take it down to between 1/16 & 1/8 thickness. Hence the ladder pattern. I was planning on working it hot.

[monstermetal]

I'll just add one thing... All of what Frosty said jives with what I understand... But one thing he did not mention is the three variables ( Time, Pressure and temperature) at inversely proportional... The more one goes up the others go down in pretty linear ratio So if cant get it hotter ( the materials melt or what ever) then use more pressure... time is also important... the longer and harder you can squeeze while maintaining temp the better bond you will have... Not that its practical... But you could theoretically make a billet just by staking it up and letting it sit at room temp for a few dozen years... When billets are commercially made they are done in a vacuum furnace built around a hydraulic press so they can maintain pressure and temp.... t

[kerrystagmer]

thats very interesting! So I could make large copper/brass billets in a vacuum furnace at 750f if i used a press in the furnace?

[Bentiron1946]

It looks like were covering all the ground we covered in this thread I wrong?
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