A common theme over the past 100 years in refractories science and technology has been to generate a protective refractories layer in a high-temperature container, often by reaction of the refractory materials with the contents (glass, slag, or atmosphere). The history of refractories during the 20th century is used in this review to illustrate how techniques-such as slag splashing, in situ spinel generation in castables, magnesia dense layer formation in magnesiacarbon brick in steelmaking, clinker adhesion in cement kilns, and viscous boundary layer generation in glass tanks-have evolved to their present status.