The floor tiles contain porosity depending on the production process. Therefore, water absorption is higher for the floor tiles. The water absorption permeability leads to problems such as visible spots on the surface of the products after laying. This situation returns to firms in the customer complaint. Impervious engobe has been investigated as a possible solution to this problem. In this study, a more sintered engobe was tried to be obtained. The amount of glassy phase increased due to increased boron frit, so water permeability decreases were observed. The permeability problem has been occurred in the samples which have prescription rates below 20% boron frit. XRD,SEM,DTA,Thermal Microscope and expansion analysis was performed. According to the results obtained from SEM images of impervious engobe samples were found to be more compact. This shows that spaces have been closed due to increasing amount of the boron frit. The lower sphere temparature have observed in the thermal microscope analysis for the engobes which contain more boron frit. So the sintering temperature has been reduced and thus the floor tiles permeability has been reduced.

Keywords: Engobe, Boron frit, Permeability.