Ceramic samples made with a mixture of 70% ball clay and 30% quartz sand were moulded and then fired at 900ºC in a electric kiln. Samples were then treated with different products and analyses and tests were performed to evaluate the phsysical changes induced by the application of these products and their effects on the quality of the ceramics. A petrographic study indicated that the ceramics were composed of quartz, small amounts of mullite and sanidine and traces of hematite. Mineral clays ( i.e. kaolinite ) disappeared during firing. Two consolidating products ( Paraloid B72 and Tegovakon V ) and one water repellent ( Silo 111 ) were applied to samples by capillarity, and physical changes ( colour, water flow, porosity and pore size distribution ) were measured. Finally, we carried out salt crystallization tests in order to determine which product improved the quality of the ceramics. Treated samples registered a decrease in prosity and a general increase in pore size. The application of Silo 111 drastically reduced water absorpption by immersion and by capillarity. This product was also responsible for a decrease in pore interconnection. Paraloid B72 did not improve any of the properties of the ceramics.