I just finished a ring that was quite a learning experience for me, but each learning experience creates wisdom which lends itself to better things! A customer asked for me to make a coil stack ring, but in one piece. I took on the challenge, but it wasn't without a lot of frustration. When you make a coil and hammer it over and over, the coil becomes a spring. If you try to push a spring together, it SPRINGS back out. I thought there was no way I'd be able to accomplish the ring. A very talented designer ( popnicute ) suggested that I anneal the metal to make it soft, and then work it around the mandrel. For the first time I heated my copper. I waited until it was red hot, then I "pickled" it by dropping the hot ring in a solution of vinegar and salt. That made it very soft. I could push that spring together for the exact effect my customer was looking for. I then put it in the metal tumbler for several hours to harden the metal again. I know that I will be using this technique again.
A fellow wire worker sent me a message asking what exactly made this such a hard ring to make. This is what I wrote (in a PM and Facebook post, combined and edited together as not to be TOO redundant.)
A coil as it hardens becomes a spring. Maintaining its structure, size, giving it strength while keeping the coil close is very difficult, especially if you're wanting hammer marks. If it's a spring, that coil will bounce back, and as it becomes stronger the harder it will fight against you. The harder the metal, the springier it becomes. Those coils want to push themselves away from each other the stronger the coil gets, so to have a tight coil I've learned that you have to anneal the metal, in other words, heat it up until it's red-hot. That will soften the metal so it's really pliable. Then, you tap it into shape, and hope the God that the tumbler will strengthen it enough that it won't bounce out of place. It was one of my most challenging endeavors.