* Formal: The archaeologist carefully brushed away the incrustation of dirt and sediment to reveal the ancient inscription.
* Descriptive: The old teapot was covered in a thick incrustation of limescale, making it impossible to pour a decent cup of tea.
* Figurative: He spoke with a passion that belied the incrustation of cynicism that had built up over the years.
* Technical: The incrustation of the boiler pipes was causing a significant decrease in efficiency.
Remember that "incrustation" refers to a hard, often layered, coating that forms on a surface. It can be used literally or figuratively, depending on the context.