Acid-resistant enamels

Claim 1

A FRIT PARTICULARLY ADAPTED FOR APPLICATION TO SURFACES OF THE ALUMINUM TYPE, CHARACTERIZED BY BEING MATURABLE INTO A SMOOTH UNIFORM ENAMEL COATING AT TEMPERATURES BELOW APPROXIMATELY 600*C, EXHIBITING A COEFFICIENT OF THERMAL EXPANSION ABOVE 12X10**6 PER *C. BETWEEN 50 AND 350*C., AND POSSESSING A HIGH RESISTANCE TO ACID ATTACK, AS DETERMINED BY THE ACID TEST HEREIN DEFINED, GIVING A WEIGHT LOSS OF LESS THAN ABOUT 0.06 GRAM PER SQUARE INCH OF AN ENAMELED PANEL, SAID FRIT COMPRISING, IN TERMS OF ESSENTIAL OXIDE CONSTITUENTS SET FORTH IN MOL PERCENT OF THE TOTAL COMPOSITION, FROM 25 TO 50% SIO2, FROM 10 TO 25% TIO2, THE RATIO OF SIO2 TO TIO2 BEING FROM 1.4 TO 5 AND THE TOTAL OF SIO2 AND TIO2 BEING BETWEEN 45 AND 60%, AT LEAST ONE TIO2-DISSOLVING OXIDE, IN THE INDICATED PERCENTAGE RANGE, SELECTED FROM THE GROUP CONSISTING OF 0 TO 10% CDO, 0 TO 8% ZNO, 0 TO 8% BAO, 0 TO 8% SRO, 0 TO 8% CAO, AND 0 TO 8% MGO, THE TOTAL OF SAID TIO2-DISSOLVING OXIDES BEING BETWEEN 2 AND 10%, THE TOTAL MOL PERCENT AMOUNT OF TIO2 AND TIO2-DISSOLVING OXIDES BEING LESS THAN THE MOL PERCENT AMOUNT OF SIO2, FROM 5 TO 15% OF LI2O, FROM 2 TO 13% OF K2O, FROM 15 TO 25% NA2O, THE TOTAL OF LI2O, K2O AND NA2O BEING FROM 25 TO 40%, FROM 0.5 TO 12% OF B2O3, FROM 0 TO 5% OF P2O5, THE TOTAL OF B2O3 AND ANY P2O5 BEING FROM 1 TO 12%, AND THE MOL PERCENT OF TIO2 IN THE SAID COMPOSITION BEING GREATER THAN THE MOL PERCENT OF B2O3 THEREIN, THE FOREGOING ENUMERATED CONSTITUENTS TOTALLING AT LEAST ABOUT 90 MOL PERCENT OF THE FRIT.