Making Bronze, Reaching Limits

This time we tried to make bronze, in a ratio of about 90% copper to 10% tin (396g and 38g).

Depending on its alloy, bronze melts at around 950º C. But since we wanted to make the bronze ourselves, we had to go about 150º C higher, because copper on its own melts at 1085º. (Tin is no problem since it melts at 232º C.)

According to our pyrometer, we had reached over 1100º C in other melts, but with only one pyrometer it's not possible to get really accurate temperature readings throughout the furnace. So we couldn't really be sure that we could reach that heat inside the crucible, and maintain it.

Jorge lit a little fire in the furnace, we added charcoal about halfway up, and then added our loaded crucible. Everything started well as usual; the temperature climbed quickly. We were having problems with the pyrometer though; the wires were coming loose and it would cut out from time to time.

Pretty quickly, as the temperature rose higher, we started seeing beautiful, entrancing wisps of green flame all around the crucible. 

Within an hour or so we were up to about 1000º C but could no longer really trust the pyrometer, as it was giving faulty readings. We suddenly hit 1480º!

So we went real old school this time, and just used our eyes. After all, the proof would be in the molten copper. 

Nearly two hours later we were apparently at 1100º C but the copper pipes were still solid. 

see the smushed pipe?

The metal was getting soft, you could press and smush the pipes, but they were not liquid. We gave it another top up of charcoal but after about 2.5 hours total, we saw that we had reached our limit.  

Conclusion: change of state not possible!

On the one hand, it was disappointing, because we were all excited to cast some beautiful golden liquid. But on the other hand, it's great to know the limits of this furnace. We know it can melt bronze, but those extra 150º needed to melt copper are out of reach! Not like this, at any rate.

But the mind starts to push for a way through. This is what came out of the crucible:

Now, what is that big black and bronze-coloured chunk there? Did some copper melt at the very bottom of the crucible and mix with the tin? I weighed all the metal and we ended with only 351g copper (45g less) and 79g of "something else". Was it some mix of copper and tin? Did some copper melt after all? How close were we?

So, what if we put the crucible lower down in the furnace? Would that make a difference? What if we used bellows? Forced air would burn up the charcoal much more quickly, but it might also push the temperature up and over this limit. It's worth trying.

How wonderful to reach a limit! This is the kind of problem that arises in the Fire Craft that you begin to appreciate, because you learn that problems like this are opportunities. That is, if you put your head on correctly, you see that now you have a chance to grow.

As the material on the Crafts states, "[The Crafts] help one to learn how to do things in a balanced way, while at the same time resolving what appear to be external problems of accuracy and detail. That is, thanks to the 'external' work in the crafts we can produce important 'internal' changes in our attitudes and approaches."

So in an analogous way, you could ask yourself, what limits do I face? What situations am I in that I would like to change but can't seem to? Where am I putting in effort, seemingly without results? What conflicts do I experience that seem intractable?

And then: Where will I find the extra energy to pass these limits? What could be my fuel? What new input, what new approach?

Perhaps in daily life we face our difficulties with frustration, wishing instead that things would just go well, and tolerating the friction as best we can. Perhaps we lack that critical mental distance to see our limits for what they are: not walls so much as invitations. The Crafts are a wonderful workshop for developing that distance alongside a playful attitude of discovery.

So, now we've got ourselves a problem! But before we tackle it, we're gonna buy some prefab bronze and cast these moulds that have been patiently waiting to accomplish their raison d'être.

It'll be good for everyone in the team to have the opportunity to pour this beautiful molten metal (so far only I have). But now I must be going, I've got some serious studying to do about bellows...