Of course, plaster walls are nothing new. Lime and gypsum plaster coated early Egyptian tombs, stucco (the Italian word for plaster) was used across the Roman Empire, and in the 15th century a ...

Archaeologists are piecing together vivid 1,800-year-old frescoes from “thousands upon thousands upon thousands” of plaster fragments, with no picture on the box to guide them.

Then, with a teardrop-shaped scraper or a 5-in-1 painter's tool, dig out the cracked plaster all the way to the wooden lath. Widen the crack as much as possible.