How to choose the wire hardness
Referring to metals, a wire's "hardness" or temper is the measurement of its malleability; how easy is the wire to control, shape and/or bend without breaking. When purchasing jewelry making wire, you will find that it is available in several different levels of hardness. Depending on the metal, the most popular jewelry wires can be categorized into four groups: hard, half hard, medium hard, and dead soft. Wire tempers may also be labeled by number:
Full Hard Wire is difficult to bend and expertly holds its shape in whatever configuration it is worked into. Hard wire can be used to make ear wires, pins, single jump rings, hook,s and clasps that will get a lot of use; because the harder the wire, the more "spring" it naturally has.
For example: the pin on a well-loved brooch will be pushed back and forth many times, therefore a harder wire will withstand more use before possible breakage.
Half Hard Wire is definitely more malleable than full hard, and it is the most popular wire temper for those who create "traditional" wire jewelry items. This wire will beautifully hold any shape it is bent into and because it will work harden quickly, it is the perfect choice for executing prong designs.
Half hard wire forms crisp clean angles and smooth spirals and curves, and it is the preferred choice when making jump rings.
This prong ring was made in half hard gold filled wire.
Medium Hard Wire is just a bit more soft than half hard wire, usually found as silver-plated and colored craft wire. Because this wire has enough temper to create almost all of the same projects as half hard wire, it can be a great substitute for those with more sensitive hands and fingers.
However, because the core of most craft wires is generally copper, it is not recommended for prong creation.
Dead Soft Wire is extremely malleable and it can be easily bent into a myriad of shapes by using just your hands. It is great for making loops, swirls, spirals, and sculpted wire jewelry pieces. Dead soft wire is also used for coiling, crocheting, knitting, and weaving, or to mix with half hard wire in certain situations.
Depending on the size (gauge) of the wire, dead soft wire does not hold its shape in stress situations, such as prongs; however, it can be hardened and/or beautifully textured by using a variety of jewelers' hammers.
Please keep in mind, that most jewelry making wire will "work harden" as it is bent and formed, making the harder tempers more difficult to work with near the end of a project. This feature can be an advantage while making certain items that will take a lot of stress such as hooks, clasps, and pins, to name a few.
The temper of a wire may also appear to harder to work with, depending on the size or gauge of a wire. For example, bending a piece of 22-gauge half hard wire is much easier than bending a piece of 14-gauge half hard wire, because 14-gauge is larger.