Mention metal patio furniture and you probably think of the light, fly-away aluminium loungers of your youth or that half-ton cast iron table and chair set on your neighbour's lawn.

But metal outdoor furniture has come a long way. Here's a quick primer on the available types and their care.

Construction Methods
Metal is fashioned into furniture in one of three main ways: extrusion, casting, and welding.

Extrusion forces melted metal through long pipes and forms long narrow tubes of metal, sometimes solid, but often hollow.

Casting metal involves a form, or cast, shaped like the finished product. The molten metal is poured into the form and then the form is removed when the metal has solidified. Cast pieces are almost always solid.

Forging, a process in which metal is heated and hammered into shape produces the type of furniture known as "wrought" metal. It uses pipes and various solid pieces of the metal and joins them together by welding or bolting.

Common Materials
The most common metal outdoor furniture is made from iron or aluminium, although the use of steel, especially stainless steel, is growing.

Iron is a chemical element that is naturally malleable and rusts easily. Vintage pieces, usually in black or dark green, can be found at premium prices and must be carefully maintained to prevent further rusting. Modern reproduction pieces will usually have a rust-resistant finish or coating that protects against chipping, scratching and corrosion. There are a variety of finishes available such as primer and paint, powder coatings and galvanizing. They are available in a range of colors and styles.

Since iron is heavy and solid, it is well-suited for windy spots where light furniture might be blown away. Don't expect it to be highly portable, though. Well-cared for, iron furnishings can last for 100 years.

Much of the iron furniture available today is wrought iron, rather than cast iron. When you're buying wrought iron, look for pieces made with solid metal rather than hollow tubing, and that are welded, rather than bolted, together. Generally, the better furniture is North American made.

Iron furniture requires more maintenance than other types of metal furniture. Clean it regularly with warm soapy water and then dry it thoroughly. Wax the smooth surfaces and apply mineral or baby oil to textured surfaces. Oil springs and moving parts once per year. Immediately touch up any scratches or rust by lightly sanding the spot with a fine steel wool. Then apply several thin coats of metal paint, letting each coat dry well before applying the next. If you're using a spray paint, apply with short light stokes.

Aluminum is a silvery, lightweight and easily worked metallic element that never rusts. Much of the early aluminum furniture from the 1960s was made from hollow-core extrusion tubing. Such furniture was extremely lightweight but not exceedingly wind-stable. Such pieces are still available today and are best used around a pool area. Cast aluminum is better used in outdoor dining or sitting areas.

Whether you're looking for extruded, cast or wrought aluminum items, there are a few items that indicate a quality piece. As with wrought iron, joints should be welded (preferably full-circumference welds) rather than bolted. If bolts are used, for example to connect webbing, they should be made of aluminum or stainless steel. Otherwise they will begin to rust even though the main frame does not.

Best quality aluminum pieces have a powder-coated finish, which determines the final color of the piece and the durability of the metal. Powder coating is a process in which colorful polyester powders are applied and then baked onto the frame.

If you're buying aluminum furniture with vinyl webbing or straps, look for vinyl that has been processed with mildew inhibitors and ultraviolet stabilizers. Any wooden pieces mounted on aluminum frames should be treated with a finish to guarantee durability.

Suntan oils, human perspiration, car exhaust and salt spray can all eat away at the powder coating on aluminum furniture. To ensure long life, clean your aluminum furniture twice a month with a solution of mild dish detergent and warm water. Rinse well. You can then apply paste car wax to any smooth finish frames.

Steel, a hard tough metal, is an alloy of iron and various small percentages of metallic elements. The alloys produce hardness and resistance to rusting. Galvanized steel has been plated with zinc; stainless steel has been alloyed with chromium and is virtually immune to rust and corrosion.

Before the production of aluminum furniture in the mid 20th century, steel furniture was common, dating from popular French-made items manufactured in the later half of the 1800s. American companies used solid steel until the Second World War when the heavy military demand for steel dictated the use of lightweight tubular (hollow) steel in outdoor furniture. Vintage steel sets can still be found at flea markets.

If you're looking at modern steel furniture, be sure the product is either stainless or powder-coated and that any hardware used is also rust-resistant.

Metal outdoor furniture in its many shapes and designs can be a wonderful addition to your outdoor living space. Choose wisely and enjoy!