Abstract: The invention regards a method for manufacturing ceramic tiles with rough surface, in which subjected to baking in a kiln is a support made of ceramic material applied on which is a first decorative layer, and a second surface layer composed of precursor glass material made up of SiO2—Al2O3-M2O-M?O—B2O3, wherein M may be selected from among Na, K, Li or a combination of these elements and M? may be selected from among Mg, Ca, Ba, Sr, Zn, Pb or a combination of these elements, during said baking occurring both the sintering of the ceramic mixture and the formation from said precursor glass material of a glass-ceramic material comprising neoformation crystals of which the main constituent is a silicoaluminate of general formula (Sr, Ca, Mg)Al2Si2O8. Furthermore, the invention regards the material for glass-ceramic coating and the tile coated therewith.

Abstract: A vitreous ceramic composition for coating ceramic articles with a zinc and alumina base capable of separating rapidly up to 50% of crystalline phase consisting essentially of gahnite. The percentages by weight of the principal ingredients of the composition are the following. SiO.sub.2 30-50%; Al.sub.2 O.sub.3 10-25%; ZnO 8-25%; B.sub.2 O.sub.3 5-20%; TiO.sub.2 0-7%; other selected oxides can be added to change the fusability characteristics and heat expansion coefficients on the basis of specific applications of the composition.

Abstract: Vitreous ceramic composition belonging to the SiO.sub.2 -Al.sub.2 O.sub.3 -LiO.sub.2 -TiO.sub.2 system in which the components are selected in ranges of definite percentages with the addition of elements exercising a given nucleating effect of promotion of growth of polycrystalline phases and designed to be used as a coating composition to be deposited directly in dry granular form on incandescent supports for producing ceramic with high crystallization speed.

Abstract: The process provides for the firing in a furnace of ceramic bodies and their coating in an incandescent state on one face with dry granular or powdered glaze when all firing reactions of the ceramic bodies have substantially reached completion; a subsequent thermal treatment fires the glaze and gradually cools the tile.The apparatus for carrying out the process provides for a furnace for firing ceramic bodies, the furnace being divided into two section between which is a device for distributing glaze over the ceramic bodies conveyed to pass through the furnace.

Abstract: An apparatus for applying glaze, in the form of granules, to hot tiles, having a dispenser including at least an inclined surface with a pouring edge for cascade or curtain coating of the glaze onto the hot tiles brought below it, preferably conveyed on rollers. Provision is preferably made for successive pouring edges aligned transversally to the tile conveyor system, and respective inclined surfaces, in particular, in the form of rotating wheels, which are internally traversed by cooling liquid.

Abstract: A process for firing ceramic bodies, in particular tiles, is disclosed, consisting in conveying the ceramic bodies through an elongated heat treatment chamber, both main faces thereof being freely exposed to heat transmission, simultaneously heating said bodies and the chamber walls by means of a heating fluid, generally combustion gases, the temperature of the portions of the chamber walls which are in view of the ceramic bodies not being higher than that of the heating fluid and controlling the flow of the heating fluid so that its actual volume flow rate, measured axially of the chamber and at the point thereof where the chamber temperature is 900.degree. C., is comprised between 4500 and 12,000, and preferably between 6000 and 10,000 cu.m. per sq.m. of transverse cross-section. Preferably the surface rate of travel of the tiles, when tiles are fired, is comprised between 22 and 30 sq.m. of tile per hour and per linear meter of inner perimeter of the chamber, for 4.5 mm.