Clinker
In metallurgy, clinker is the term for the material remaining after the process of smelting a metal ore. It may contain ash from the smelting fire, and also the impurities, rock, and unreduced metal oxides. Clinker is used in the manufacture of Portland cement.
A clinker is also the name of the rocky glassy object left over from burning coal.
In boat building, clinker is a method of constructing wooden boats by fixing planks to a frame so that the planks overlap each other gaining support from the frame and from adjacent planks.
