Knowing how to choose the correct hardness of sheet and wire metals for your jewelry techniques and designs helps you achieve the good-looking, long-lasting results you want. Below, we share some of what we know about metal hardness and we hope it enriches your experience at the bench.
Metal hardness is one of the trickiest things to try to explain—the term is relative to the particular metal or alloy, for starters; depending on the elements that make up each particular alloy, what’s called “hard” in one metal won’t bend, form, work, or feel the same as a material designated as “hard” in another metal.
The Hardness Relativity
Metal is composed of individual crystals arranged in a pattern and density specific to that type of metal. Because of this, the range of hardness from soft to hard will be relative to each metal (see the Vickers hardness chart below). Dead-soft sterling, for example, does not feel or behave the same as dead-soft white gold.
If you will be soldering on the piece you’re making, you may as well start with dead soft because it’s easy to work with and any hardness the metal may have will be lost when you apply heat to solder. If you will be cold-working the metal (manipulating, forging, twisting, folding, etc.), you may want to start with dead-soft metal and anneal it every so often as needed to resolve the work-hardening and return the metal to a dead-soft state. Jewelers who wire-wrap usually use 1/2-hard wire because it holds its form well in the finished design—as the wire is bent to wrap it, the working hardens the wire further so that the finished jewelry is stronger.
Any kind of cold working such as rolling, drawing, bending—even uncoiling and coiling wire—increases the hardness incrementally. Annealing can return the metal to dead soft, and further work will again begin to harden it. Mills that make sheet and wire typically measure the hardness of their products based on how much the product has been worked (a percentage of reduction, for example, in rolled sheet or drawn wire) since they were last annealed to dead soft.
The descriptions below offer, in general, what you can expect from the various hardnesses, but remember that these will vary in degree depending on the metal you’re working with, what you’re making and how you work.
Metal that is dead soft is in a relaxed state at its molecular level, so it is easy to bend, shape and hammer. The act of bending or shaping will gradually work-harden the metal—right up to the breaking point. Dead soft metal will not hold its shape if put under stress in structures such as hinges or clasps.
Metal that is 1/2-hard has been worked a bit, tightening the grain at the molecular level. This metal is harder to bend and hammer, but it is still possible in some cases to shape the metal—it just takes more force. While still malleable, it will also hold its shape under a certain amount of stress; it is ideal for wire wrapped structures that will support other components. If you are fabricating an item that needs both strength and a thinner gauge, you would probably choose 1/2-hard.
Metal that is tempered (or significantly work-hardened) will be difficult to bend but will hold whatever bend you put into it pretty stubbornly. This hardness is ideal for clasps or hinges.
Metal thoroughly hardened will lose pretty much all of its malleability and will actually spring back into its original shape when bent by hand. This hardness is ideal for ear wires, jump rings head pins and pin components.See also:
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