Ok, this is probably going to be a long post, and rather technical as well. Those interested in joining mokume gane, bear with me. I have already tried and succeeded in joining metals using torque plates in a gas forge. Essentially you press the metal stack between two steel plates, and heat it up in a reducing forge atmosphere until one of them, or a eutectic alloy of them just melts, then you remove them from the heat, press them, and you are done. This is the traditional Japanese method, and it requires an eye for temperature, as you must judge by eye when the metals are melting and move fast, otherwise your stack is ruined.
Another method is bringing your stack to a temperature below melting point, and keep it there for some time, under as much pressure as you can. Hence, you compress the stack in a hydraulic press, and stick it in an electric kiln, where you can pretty accurately regulate the temperature. However, the kiln does not have a reducing atmosphere, just plain air so your metals will oxidize rapidly once heated up, and again your stack is ruined.
So, after reading Ian Ferguson's book, and also reading about James Binnion on the net, I tried the latter's method, i.e. placing the stack and torque plates in a stainless steel container, filled with charcoal particles.
Here you can see the necessary implements, a stainless steel box, with a lip and a lid, the torque plates with the stack in them, crushed charcoal, and some refractory cement to seal the box.
Here is the sealed box before being put in the heated kiln,
... and here just as it came out a good 3 hours afterwards, still glowing (it was red hot, but I guess the camera read that as blue).
Finally, a successfully joined mokume stack, made of 19 layers of copper and brass.
The good thing about this method is that by keeping the temp lower than the melting point, you hopefully avoid the risk of melting your stack, and hence you can safely experiment with more presious metals as I intend to do.
