Ceramic glazes can be applied by means of several technologies but the most common and popular is the airless spray system. However, sometimes glazes can still be discharged on the raw tile by means of bell or vela systems. Each application system required different evaluations about the glaze's rheology. The glaze must be marked by specific properties according to the system with which is applied along the production line. The episode focuses on these differences and on the chemicals that can - or must - be used to get the proper features. At the end, a brief focus on synthetic chemicals, very useful to prevent the proliferation of bacterial attacks before and during application.