Metal alloys, however, contain two or more ingredients, which after combining with each other, form a new metal. Often it takes on new characteristics, such as color, density, higher or lower melting points, etc. Over the years, these combinations have varied greatly. Plates and hollowware that may be used for serving food, usually contain a mixture without lead, due to lead's carcinogenic nature. Antimony helps keep pewter bright and almost tarnish free.
Copper acts to soften pewter, making it more workable.
Other pewters contain bismuth, lead, copper, etc., depending on the nature of how the pewter is to be used. Properties are changed in order to give the pewtersmith better control over the end results of his work and to keep the metal looking nice for many years to come. Some pewter pieces need a little extra strength, such as buttons, in order for them to perform their intended functions. Changes are made to suit the need. Through the centuries, pewter has contained metals, such as silver and lead.