Soldering terminology

Oxidation products deposited on the surface of a melt are usually known as slag. However, the term dross does not only comprise the oxidized metal dispersed in the melt, but the deposits on its bottom as well. The term sludge is also used in this sense. However, sludge also refers to non-metallic wastes, such as handled during sewage treatment. S lime is another frequently used expression. All these terms refer to waste and are often used without a clear definition. Solder dross refers to tin and lead oxides developing when solder is melted.