Today as in the past, Scagliola comes from a mineral, Selenite, a variety of gypsum that in its natural state appears in the form of thin plates or scales (thus the name "scagliola", from the Italian word "scaglia" or scale).
After the mineral is cooked and ground to a fine powder, it is mixed with pigments of colored earth and with animal glues to form a thick paste.
The original design is applied onto the slab of marble or of scagliola, traced over with hammer and chisel, and then carved into the slab.
The colored paste is applied into the design and after hardening is flattened with water and pomice stone.
Then the slab is ready to to be incised again and a new color applied.
For elaborate decorative motifs, as was already practised in the nineteenth century, subtle gradations of color are added in diluted scagliola applied by hand with a fine paintbrush.
Lastly, the slab is polished with polishing stones, wax, and lacquer.