Sterling Silver Wire
How To Heat-Harden Sterling Silver
This process will increase the strength of the metal and reduce its ductility. To harden the metal, you will be applying heat to the metal; whenever you apply heat to sterling, surround it with nitrogen, argon or forming gas or cover it with flux to prevent the metal from oxidizing.
IMPORTANT: Fine silver cannot be heat-hardened.
Annealing Sterling Silver
Annealing sterling silver, recovers metal that has become work-hardened, leaving the metal to become more workable.
Step 1 Anneal the sterling silver between 1000°F and 1200°F (537°C and 648°C).
Step 2 Heat the sterling at temperature for 30 to 60 minutes to achieve a Vickers hardness of 66–76dph.
Please Note: During annealing, protect the metal against exposure to oxygen by surrounding it with nitrogen, argon or forming gas. If this isn’t possible, protect the metal by covering it with flux contained in a stainless steel pan.
How To Understand Metal Hardness
These definitions will be helpful when choosing the hardness best suited to your jewelry technique and design goes a long way toward achieving the professional result you want.
Metal that is dead soft is in a relaxed state at the molecular level, so it is easy to bend, shape and hammer. The act of bending and 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 half-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 will take 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 fabricating an item that needs both strength and a thinner gauge, the best recommendation is half-hard.
Metal that is tempered (or significantly work-hardened) will be difficult to bend but will hold whatever bend you put into it. This hardness is ideal for clasps or hinges.
Metal thoroughly hardened will lose 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 and head pins.
Metal hardness is changeable. If you start with dead soft and work it or stress it, you will harden it. If you start with hard metal and heat it (either by soldering on it or by deliberately annealing it) you will soften the metal--all the way back to dead soft.