Up to 70 percent of dross is bound-up metal that would otherwise be available for soldering.

During wave soldering, printed circuit boards pass over the crest of a continuously flowing fountain of molten solder. It's a quick way to solder many joints at once, but the process is not without drawbacks, and one of the biggest is dross.

Dross is the oxide scum that forms on the surface of molten solder. How much dross is generated during production depends on the temperature and agitation of the solder bath. The more turbulent the solder surface, the more dross gets produced.