Lead is one of the most commonly used metals for extrusions. It is a bluish-white metal that is lustrous, ductile, very soft, highly malleable, and a relatively poor conductor of electricity. It is resistant to corrosion but it tarnishes when exposed to air. Although all these properties are very desirable, they come with a price. Lead is one of the four metals with the most harmful effects to human health. This makes the use of lead extrusions more controversial than that of PVC extrusions.
Lead extrusion follows the same process used in other metal extrusions. Lead is softened by heat and forced through a shaped die on one side of the extruder. The material emerges from the other side possessing the shape of the die. The material is then cooled, polished, packaged, and distributed.
Today, lead extrusions are commonly used as sheathing in high voltage power cables to prevent water diffusion. They are also used in creating munitions, cables, solders, and organ pipes.
The most common lead extrusion products are lead pipes. Actually, although metal extrusion is relatively a new technology, the early Romans used lead pipes as drains in their baths. The Romans probably picked lead as the most suitable material for their pipes because of the element’s soft nature. Lead is one of the softest metals, making it easier to mold and shape compared with other metals. Until the early 1970s, lead was used as a material for water pipes with small diameters.
The use of lead as a material for lead pipes was banned because of the growing concerns regarding the element’s damaging effects on the environment and human health. It can enter the body through uptake of water, air, and food. It can dilute drinking water when pipes corrode, which is very likely to happen, especially when the water is acidic. Harmful effects of lead include kidney damage, miscarriage, nervous system disruption, brain damage, declined sperm counts in men, and diminished learning abilities in children.