Wire Properties - Work Hardening

I have written a series of articles covering some basic how to's and general information on working with wire and sheet metal so will post excerpts of the article here for free hopefully once a week.

Also during this time, some exciting fun technique tutorials will be available for sale on my website in a month time, so about August 2011.

The blog notes will be a companion for most of my tutorials and offer the absolute novice some really good solid know how for working with wire work. Stuff it took me several years to learn through trial and error.

I have written these articles for you to use but if you use the information or wish to cite, please give credit where credit is due and reference my website www.yourjewellery.com. - Amanda Katz

Metal Qualities

The most common metals to work with in jewellery are brass, copper, silver and gold but each metal has different qualities that endure or repel the jeweler. These qualities are hardness/softness which affects ability to cut, bend and manipulate. In ease of working without soldering the metals are easy to hardest as follow: fine silver, sterling silver, copper, gold then brass. Economics often dictates what metal is chosen for a design as well.

Wire Technique

Hardness

Wire comes in three rates of hardness that equates to work hardening and annealing of wire before it is sold. As you work with wire, it gets work hardened, or the molecules in the wire line up more rigidly thus making the piece of wire less flexible and more brittle.

Work hardening happens by moving the metal around such as cutting, hammering, coiling or bending and even light filing. Work hardened metal is necessary for a project requiring stiffness like the pin on a brooch or for supporting a heavy weight like a heavy necklace with a large focal bead. One disadvantage of overworking the wire is eventually it becomes brittle and will snap with too much force.

When wire becomes too work hardened, a flame from a torch or even the kitchen gas stove is applied until the metal becomes a light pink (not red) and quenched in water. By applying high temperature evenly to the wire, it allows the molecules to loosen up which returns the wire to a bendable, softer form to work with again. One side effect of working wire with flame (such as sterling silver) is that the surface becomes covered with fire scale which requires pickling, sanding back and then polished up again either by hand or in a tumbler filled with steel shot. Thus when planning a project, it is better to plan ahead to know what hardness of wire is required before diving into the deep end.

Commercial wire is available in three hardnesses: Dead soft, half hard and full hard.

Dead soft means the wire is recently annealed, therefore is very flexible and soft to bend. There will be quite a bit of manipulation left in dead soft before it becomes brittle thus is best for wire coiling and weaving free hand sculptures or setting stones without solder. Dead soft is extremely easy to bend without much force so is unsuitable to supporting heavy weighted beads.

Half hard means the wire has been worked enough to give it a small amount of stiffness. It requires more force to bend than dead soft so is suitable for weight bearing projects, jump rings, and chain mail in thicker gauges. Thin gauges of half hard can still open by force of project weight though.

Full hard has been work hardened to the point that a considerable amount of pressure is required to manipulate the wire. Very suitable for heavy weight support, ear wires and projects where just a few bends in the stiff wire is necessary. Because full hard has already work hardened, it will become brittle quickly. Full hard is good for wire ring shanks, support frames for wire wrapping and jump rings in finer gauges.

Choosing the wire required is important in the planning stages of a project. Using the right stiffness of wire is important also to reduce strain on the hands, as coiling full hard by hand around a mandrel would be a much harder task force wise versus using dead soft wire.

Copper and sterling silver wire both have about the same work hardening properties, similar dead soft feels right on up to brittle breaking point when overworked. Brass wire tends to be stiffer even after annealing and will achieve overworked breaking point much quicker than copper or sterling silver in the same project. Fine silver, being 99.9% pure silver starts off dead soft and after much work hardening will possibly achieve half hard but will never become brittle to breaking point.

Next Week: Wire Gauge