Even with the introduction of plastic and the continual use of traditional wood we still use a fair amount of metal outdoors. Metal railings, fences, backyard furniture and even the occasional sculpture are not unusual. Even with the harsh conditions outside the right metal can still be quite long lasting. It is useful to know the properties of the different materials.
Casting – Molten metal is poured into a mould, forming a (usually solid) piece.
Forging – Heated metal is hammered into shape. Rather like a traditional blacksmith.
Extrusion – Molten metal is forced though long pipes, and cools to form tubes.
Iron – Heavy and prone to rust over time. A good primer, paint or galvanizing treatment will prevent rusting, and look rather good. Cast iron tables and chairs make good outdoor furniture, with occasional repainting. Iron fences were once popular, but are replaced by wood or aluminium.
Aluminium – A light and useful metal, which is rust free under moderate conditions. It is less popular for furniture, unless you want something portable, but very popular for fences and barricades. Though it is not easily painted it can be powder coated, giving a fairly good range of colours.
Steel – This is mostly iron alloyed with some other metal and carbon. Combinations that include chromium are virtually rustproof. These are fine materials, long lasting, but unless they are the rustproof variety they require regular painting.
Outdoor balustrade fences are often best made of stainless steel or powder coated steel, which is also rust resistant. Unless exposed to extreme salt or chlorine conditions these should be maintenance free.
Pool fences are often made from aluminium. This is rust proof, though chlorine from pools will slowly compromise the rust resistant properties. Pool fences should be washed with warm, soapy water every few weeks.