Smalti - Italian mosaic tiles
Smalti is traditional hand-cut mosaic glass that has a different look and feel from molded tile. This is the glass of choice for reproducing antique mosaic art, icons or making modern interpretations of classical designs. Smalti is different from regular glass tile in that regular glass tile are cut in bands directly from the surface of the glass slab, creating relatively regular, smooth and even squares. Smalti, on the other hand, is rectangular in shape and is intriguing precisely because it is cut at an angle to the glass slab. It is the sheared, uneven cut side of the glass which serves as the top surface of the tile. It is this cut that gives smalti its reflective, shimmering brilliance that cannot be matched.
The creation of smalti starts with the same basic ingredients used to make other types of glass: sand, soda and stabilizing compounds. These ingredients, along with the coloring agents, are heated in furnaces at extremely high temperatures to create a glass paste.
When the color and firing have reached the desired point – and this may take days – the fused molten paste is removed from the melting pot. A long, heavy spoon is beaten rhythmically on the paste, as the glowing ball of glass is squeezed and flattened into oblong slabs, and then the slabs are slowly and methodically cooled.
The large glass slabs are first sliced into rods and then chipped down into the small rectangles you see on the walls of the stations of the Green Line.
This information about smalti came from: mosaicsmalti.com