USE OF LOW COST RAW MATERIALS IN POROUS SINGLE FIRING PROCESSES F. SANDOVAL DEL RÍO, V. BELTRÁN PORCAR, J.Ma. GONZÁLEZ PEÑA and J.E. ENRIQUE NAVARRO J. Phys. Colloques, 47 C1 (1986) C1-549-C1-553 DOI: 10.1051/jphyscol:1986183