Lead is a soft, silvery metal that lacks strength, so it is alloyed with various elements to impart useful properties. These alloys may be cast into a wide variety of shapes and can be rolled into sheets of varying thickness. Alloying with zinc, bismuth, silver, tin, arsenic, and antimony improves hardness and strength. Zinc and bismuth also aggravate corrosion in some circumstances, but tin, tellurium, arsenic, and silver reduce or prevent it.
Alloys of low melting point, containing from 10 to 15 percent tin, are used as solders. These are particularly useful for joining aluminum with other metals where lower soldering temperatures are required. They also have good wetting and bonding capabilities. A half-lead/half-tin alloy is the most popular general purpose solder.
Other lead alloys with a lower melting point are used in the manufacture of electrical wire coatings and as insulation for electric cables. In these applications, the corrosion resistance of the material is more important than its melting point or strength.
Lead is a dangerous element to work with and therefore alloys with lower melting points are preferred. In addition to lower melting points, these alloys require less heat to melt and are easier to liquefy. Alloys with low melting points are usually made of a non-eutectic alloy that requires lower temperatures for solidification. These alloys are used for a variety of industrial purposes, including the casting of foundry patterns and fusible elements in safety devices.