We Melted Brass

It worked! We melted brass in our little primitive clay furnace:

 To make sure we were working with the right material, I bought a thin rod of guaranteed brass

and sliced it up into five pieces, and put it in the crucible. We forgot to take photos at first, excited and busy, but here are the rods sticking up out of the crucible, surrounded by charcoal (thermocouple poking in from the right).

We started the fire around 2pm and the temperature increased very steadily and easily. 

Unfortunately, we didn't take notes (what was I thinking?) but we guess that in about an hour the pyrometer was reading over 1000º C. 

I was sure it couldn't really be that hot (a reading with only one thermocouple is not so accurate) so we let it go a little while longer, but then finally pulled out the crucible to have a look.

The brass rods were no longer poking out of the crucible, meaning they had melted! 

But we could see they weren't fully melted, so we put the crucible back in, added more charcoal, and started a second round.

At some point I heard a crack, and sure enough, the stone base under the furnace split right in two. (The stone base allows us to move this very heavy furnace onto the wheeled board and in and out of the garage; something to figure out for next time.)

We were all very entranced by this little piece of brass that spilled out when we examined the crucible the first time. It was such a beautiful colour - you begin to understand the fascination with gold.

In this second round, the highest the pyrometer read was 1057º C, and shortly thereafter (too shortly!), we pulled out the crucible again, figuring all the brass had melted.

But, it hadn't. Clearing out the ash, we found:

The rods had started to melt, and one of them actually created a neat little band around the others, but to have all the rods melt would have required more time in the furnace (in order for that 1000º+ temperature to penetrate everywhere thoroughly and more evenly). 

But the proof is there! We must have reached 930ºC (roughly the melting point of brass) and that should be hot enough to melt bronze (melts around 913º, depending on the alloy). 

Next time we thought to see if we could actually make bronze ourselves, by putting copper and tin into the crucible. Copper will need quite a bit more heat - around 1084º to melt - but it'll be a good way to test the limits of this little furnace which so far is doing a great job.

Hell, it was so easy to fire up that we all enjoyed chatting and hanging out under the grapevine while the natural draught of the furnace did its thing. 

Note: Flip-flops are not at all recommended footware!