by Thomas Foschini17   Febbraio   2014

A new challenge in the "digital glazing"

Inkjet technology as a valid alternative for the contactless application of different types of glaze on a great variety of manufacturing: that’s the idea that stands behind DPM, Digital Printing Materials, the digital micronic glazes for ceramic tiles presented by Esmalglass Itaca Group. It’s a family of products which are especially designed for their application through digital systems and which are able to compete in terms of aesthetic and technical specifications with the most traditional ceramic tile glazing techniques.

Impermeability, lack of porosity, surface finish (bright, matte, satin-finished), colouring on matte interface is traditionally expected from glazing so as to safeguard silk-screening decoration (silk screen printing) and special effects such as shiny surface. The act of glazing also makes decorations anti abrasive. “Ceramic tiles glazing usually takes place at room temperature, says Armando Meletti, Esmalglass-Itaca general manager, through production chain, bells, airless or other analogical systems. Compounds are normally prepared by ceramic glazing manufacturers who mix frits with raw materials (pigmented ones if coloured) in a watery solution or high level coating silk screen prints with medium silk screenings.

“Our innovation  –continues Meletti – lies in glazes which are suitable for heavy digital deposit and can replace conventional glazing, flat screen printing and rolls or fumés with the same ‘contactless’ digital technique”. The layer of ceramic glaze that is applied through both contact and contactless process is traditionally made of 20-45 micron particles and the amount of material deposited can reach 1kg/m2 or more. The alternative, which stems from Esmalglass-Itaca digital inkjet decoration Drop on Demand (DOD), first developped in 2005, is the application of glazing through the technique used for digital decoration which allows to decorate and glaze simultaneously and in a synchronized manner, enhancing decoration results and exploiting the productivity advantages brought by digital technology.

To compete with traditional glazing techniques current aesthetic standards such as materiality, contrast, deepness, and tactile sensations (all dependent on the quantity of material applied) must be respected. “These glazes – continues Meletti – have the right chemical and physical specifications for digital decoration, in particular they have particles of such dimension so as to enable the application of a 50 nanomicron thin layer”, allowing to get decorative effects similar to those produced by analogical glazing. Other specifications are lack of sedimentation, total miscibility with water, and total compatibility with the other ingredients of digital printing.

 
“Digital glazing involves advantages such as total control of production process, from mixing of raw materials to their chemical and physical processing, up to ceramic application” observes Meletti. Patented by Esmalglass, the new micron DPM digital glazes would enable not only to replace applications through contact techniques but also to “reduce production process, development times for new products, defectologies normally related to traditional glazing, enhancing at the same time drawing/format swap’s flexibility and rapidity”.

DPM glazes can be applied through DOD inkjet heads, similar to those used in digital decoration, allowing the products to be used on a variety of different machines. “This type of glaze – says Meletti – fits heads similar to those used for digital decoration and is especially designed for applications on porous materials where water is absorbed allowing glass firing (at a temperature of 500 to 1300°C) to bring the desired effects”. Furthermore –Esmalglass representative concludes - the peculiar inkjet glaze specifications avoid further control on materials which is normally necessary with traditional glazes as the product respects viscosity, surface tension, density and solids content parameters typical of digital decoration inks.

Physical properties and specifications of high discharge digital glazes (DPM micronic) patented by Esmalglass