They are elements of great charm, for the surprising and wonderful suggestions of light they produce.
They can be used mainly for wall mosaics, given the low wear resistance which makes them highly perishable if subjected to foot traffic.
A brief hint of history: in 1203, Venice called the glass masters of Constantinople and started the Venetian glass factories.
The production of glass and metal mosaic tiles in Venice disappeared towards the middle of the XNUMXth century and was reintroduced in the XNUMXth century by Lorenzo Radi, with the rediscovery of lost secrets, the experimentation of new materials and the introduction of reverse mosaic processing.
Angelo Orsoni contributes to the innovations with the introduction of coal heating and the roller to press the glass.
Experiments with new materials, however, give rise to not very resistant enamels: in San Marco the mosaics of the nineteenth century are more damaged than the ancient ones.
Different types of tiles with a glass component are produced:
homogeneous glass tesserae: tesserae of intense homogeneous black, blue, purple, brown and green color that prevent transparency and therefore the vision of the underlying bedding mortar.
weave in dough vitrea: colored glass tesserae can be semi-transparent or opaque; they are produced in 4 or 5 color tones; the most intensely colored are made of transparent glass, because the coloring prevents the base mortar from being seen, while the lighter shades are obtained with the dispersion of a white crystalline mineral which increases opacity, with a smaller quantity of dye.
opaque tesserae: paste tesserae vitrea in which the abundance of crystalline phases makes the glass completely opaque.
enamels: translucent and opaque tiles that are brighter and brighter in which the gloss effect is due to lead oxide: for this reason they are also called lead glasses. They consist of a glassy mass bearing in suspension a colloidal dispersion of oxides of various metals with a coloring, opacifying and oxidizing function.
Source Wikipedia.it
