Method for internally coating a hollow glass body

Method for internally coating a hollow glass body comprising, in the following order:

• (a) applying by a spraying device, onto at least an internal surface of said hollow body, at least one coating composition, to obtain a coated glass body, wherein the coating composition is in the form of aqueous dispersion comprising at least one glass frit and at least one polymeric dispersing agent, said agent being present in such an amount that said composition has a thixotropic index lower than 200 second;
• said hollow body and said spraying device being in movement with respect to each other, said movement comprising keeping said hollow body rotating on itself during the application of said coating composition;
• and
• (b) subjecting said internal surface comprising said coating composition to a thermal treatment at a temperature in the range of 450-800° C., so as to obtain a vitrified coating layer,
• wherein said frit is present in the composition in a quantity comprised in the range 50-80% by weight with respect to the weight of the coating composition,
• wherein said polymeric dispersing agent is present in the composition in a quantity comprised in the range 1-20% by weight with respect to the weight of the liquid phase of said dispersion, and
• wherein said frit comprises, based on a total weight of said frit:
• SiO2 30-45%;
• Na2O 1-4%;
• P2O5 0-1%;
• CaO 2-6%;
• K2O 2-6%;
• TiO2 4-9%;
• ZnO 8-18%;
• BaO 0-2%;
• Bi2O3 2-6%;
• and
• B2O3 10-20%.