Smalti is a type of glass paste (not as brittle as ordinary glass) with each individual color poured into a small glass puddle referred to as a “pizza” (or “tortilla” depending on what part of the world you are in). These pizzas can be chiseled into tesserae, small cubic or rectangular bits of glass, marble, or gemstones which are used to create micromosaics. A chisel is used to cut the smalti in order to form an uneven surface that becomes the top of the tesserae. This is where the glass has the most intense color and the rived surface catches the light to make the tesserae glisten. These highly reflective, opaque tesserae are set directly into the cement of a mosaic to form a design or picture.
Another method used to create tesserae for micromosaics is filati. These are glass rods, typically handmade from smalti, rather than other glass. Each pull of the glass results in subtle changes in the color that cannot be duplicated. Filati originally was created in order to produce micromosaics (c.1775.) Through time methods evolved, filati continued to be handmade and pulled but the artisans began to mix and combine colors. The term used for these blends is ‘malmisticato’ (translates from the Italian as badly mixed) resulting in a marbled effect. Traditionally, filati was cut into miniature lozenge-shaped tessera, further innovation was to cut the filati into circular, square, teardrop, leaf, and “C” shapes allowing the artisan more color and shape choices to choose from.
Tesserae (from Latin, plural for tessera: having 4 corners) are the small bits of glass hand chiseled from smalti or filati and assembled in a design or image to create a micromosaic.