After the acanthus leaves have been work hardened by cold working, I found it increasingly difficult to do any additional hammering and decided it was time to anneal the work. Annealing is the process of stress relieving the metal so that it will soften. A metallurgist can explain this process in greater detail than I ever could, so I will explain it from the craftsman's point of view.

As brass or copper is cold worked, the crystaline structure of the material becomes compacted. After continuous cold working, the work is so compacted that it does not readily give. It will actually get to the point that it will crack. Once its plasticity under the hammer can no longer be sensed, it is probably time to anneal the piece. This is when you must determine if you really need to anneal the work.

If you know that you still have several processes to perform, then you should go ahead and anneal the piece. On the other hand, if you are almost finished forming but you need to tweek it just a bit, then brace yourself and continue to strike. For once you have annealed the work, you will have to go back over the complete surface to re-harden it. Otherwise you will find that the work is too soft and can easily loose its form. You do not want to attach this to your finished artwork because it will likely become deformed over time.

To anneal the acanthus leaves, I decided to use a #14 rosebud with oxy-acetylene tanks. The flame should be a soft reducing flame - less oxygen mixture. You can tell you have a reducing flame by looking at the tip of the rosebud. It should be a white color where the individual flame ports are NOT sharp. The white portion of the flame should be 2-4 inches long. This will reduce oxidation of the surface and also help disperse the heat over a larger area.

Start heating the piece with the feathered end of the flame. Do NOT put the flame too close to the piece or you may see it disintegrate right in front of your eyes! Bring up the color of the work to a dull red over as large an area as possible. Note that if you have left the resist pattern as I did, it will burn off quite nicely and leave a less oxidized color on the underside of the leaf (see fourth picture on left.)

After the resist has burned off you will notice that a rainbow of colors will follow the movements of your torch as you pass it over the surface. These colors are very intense and are caused by variations in the lower temperature ranges. You will also notice that because of the high heat conductivity of brass, the colors change very quickly. This should also make you realize that it is very hard to get a uniform heat over the entire surface. Once you have heated the complete piece to a dull red, quench it in water. This action will freeze the crystaline structure in its softest state.

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